diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3855e8d..e5d0fc7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -117,14 +117,13 @@ set(SOURCE_FILES
         user/cgi_sockets.h
         user/ansi_parser_callbacks.c
         user/ansi_parser_callbacks.h
-        user/user_main.h
         user/wifimgr.c
         user/wifimgr.h
         user/persist.c
         user/persist.h
         include/helpers.h
         user/syscfg.c
-        user/syscfg.h user/ascii.h user/sgr.h)
+        user/syscfg.h user/ascii.h user/sgr.h user/apars_utf8.c user/apars_utf8.h user/apars_logging.h user/version.h user/apars_csi.c user/apars_csi.h user/apars_short.c user/apars_short.h user/apars_string.c user/apars_string.h user/apars_osc.c user/apars_osc.h user/apars_dcs.c user/apars_dcs.h)
 
 include_directories(include)
 include_directories(user)
@@ -146,6 +145,7 @@ add_definitions(
         -DADMIN_PASSWORD="asdf"
         -DGIT_HASH="blabla"
         -DDEBUG_ANSI=1
+        -DDEBUG_ANSI_NOIMPL=1
         -DESPFS_HEATSHRINK)
 
 add_executable(esp_vt100_firmware ${SOURCE_FILES})
diff --git a/Makefile b/Makefile
index 6e1a9d1..57c62bd 100644
--- a/Makefile
+++ b/Makefile
@@ -73,6 +73,7 @@ CFLAGS += -DADMIN_PASSWORD=$(ADMIN_PASSWORD)
 
 # Debug logging
 CFLAGS += -DDEBUG_ANSI=1
+CFLAGS += -DDEBUG_ANSI_NOIMPL=1
 CFLAGS += -DDEBUG_INPUT=1
 
 # linker flags used to generate the main object file
diff --git a/user/ansi_parser.c b/user/ansi_parser.c
index 9786271..0ed6ef1 100644
--- a/user/ansi_parser.c
+++ b/user/ansi_parser.c
@@ -2,9 +2,9 @@
 /* #line 1 "user/ansi_parser.rl" */
 #include <esp8266.h>
 #include "ansi_parser.h"
-#include "screen.h"
+#include "ansi_parser_callbacks.h"
 #include "ascii.h"
-#include "uart_driver.h"
+#include "apars_logging.h"
 
 /* Ragel constants block */
 
@@ -14,12 +14,12 @@ static const char _ansi_actions[] = {
 	3, 1, 4, 1, 5, 1, 6, 1, 
 	7, 1, 8, 1, 9, 1, 10, 1, 
 	11, 1, 12, 1, 13, 1, 14, 2, 
-	3, 6, 2, 8, 9
+	3, 6
 };
 
 static const char _ansi_eof_actions[] = {
 	0, 1, 1, 1, 1, 1, 1, 1, 
-	1, 1, 0, 0, 0, 0, 0, 0
+	1, 1, 0, 0, 0, 0, 0
 };
 
 static const int ansi_start = 1;
@@ -27,7 +27,7 @@ static const int ansi_first_final = 10;
 static const int ansi_error = 0;
 
 static const int ansi_en_CSI_body = 5;
-static const int ansi_en_StrCmd_body = 7;
+static const int ansi_en_STRCMD_body = 7;
 static const int ansi_en_charsetcmd_body = 9;
 static const int ansi_en_main = 1;
 
@@ -62,7 +62,7 @@ static char history[HISTORY_LEN + 1];
 #endif
 
 void ICACHE_FLASH_ATTR
-apars_handle_badseq(void)
+apars_show_context(void)
 {
 #if DEBUG_ANSI
 	char buf1[HISTORY_LEN*3+2];
@@ -104,7 +104,6 @@ ansi_parser(char newchar)
 	static int  arg_ni;
 	static int  arg_cnt;
 	static int  arg[CSI_N_MAX];
-	static char csi_char;
 	static char string_buffer[STR_CHAR_MAX];
 	static int  str_ni;
 
@@ -114,12 +113,12 @@ ansi_parser(char newchar)
 	// Init Ragel on the first run
 	if (cs == -1) {
 		
-/* #line 118 "user/ansi_parser.c" */
+/* #line 117 "user/ansi_parser.c" */
 	{
 	cs = ansi_start;
 	}
 
-/* #line 92 "user/ansi_parser.rl" */
+/* #line 91 "user/ansi_parser.rl" */
 
 		#if DEBUG_ANSI
 			memset(history, 0, sizeof(history));
@@ -155,15 +154,16 @@ ansi_parser(char newchar)
 				return;
 
 			case TAB:
-				screen_tab_forward(1);
+				apars_handle_tab();
 				return;
 
 				// Select G0 or G1
 			case SI:
-				screen_set_charset_n(1);
+				apars_handle_chs_switch(1);
 				return;
+
 			case SO:
-				screen_set_charset_n(0);
+				apars_handle_chs_switch(0);
 				return;
 
 			case BEL:
@@ -174,8 +174,8 @@ ansi_parser(char newchar)
 				}
 				break;
 
-			case ENQ: // respond with space (like xterm)
-				UART_WriteChar(UART0, SP, UART_TIMEOUT_US);
+			case ENQ:
+				apars_handle_enq();
 				return;
 
 				// Cancel the active sequence
@@ -217,9 +217,13 @@ ansi_parser(char newchar)
 _resume:
 	switch ( cs ) {
 case 1:
-	if ( (*p) == 27 )
-		goto tr1;
+	switch( (*p) ) {
+		case 7: goto tr1;
+		case 27: goto tr2;
+	}
 	goto tr0;
+case 0:
+	goto _out;
 case 2:
 	switch( (*p) ) {
 		case 32: goto tr3;
@@ -250,24 +254,24 @@ case 2:
 			goto tr6;
 	} else
 		goto tr6;
-	goto tr2;
-case 0:
-	goto _out;
+	goto tr1;
 case 3:
 	if ( (*p) > 71 ) {
 		if ( 76 <= (*p) && (*p) <= 78 )
 			goto tr9;
 	} else if ( (*p) >= 70 )
 		goto tr9;
-	goto tr2;
+	goto tr1;
 case 10:
-	if ( (*p) == 27 )
-		goto tr1;
+	switch( (*p) ) {
+		case 7: goto tr1;
+		case 27: goto tr2;
+	}
 	goto tr0;
 case 4:
 	if ( 48 <= (*p) && (*p) <= 57 )
 		goto tr10;
-	goto tr2;
+	goto tr1;
 case 5:
 	switch( (*p) ) {
 		case 59: goto tr13;
@@ -287,7 +291,7 @@ case 5:
 			goto tr15;
 	} else
 		goto tr11;
-	goto tr2;
+	goto tr1;
 case 6:
 	if ( (*p) == 59 )
 		goto tr13;
@@ -299,9 +303,9 @@ case 6:
 			goto tr15;
 	} else
 		goto tr15;
-	goto tr2;
+	goto tr1;
 case 11:
-	goto tr2;
+	goto tr1;
 case 12:
 	if ( (*p) == 59 )
 		goto tr13;
@@ -313,7 +317,7 @@ case 12:
 			goto tr15;
 	} else
 		goto tr15;
-	goto tr2;
+	goto tr1;
 case 7:
 	switch( (*p) ) {
 		case 7: goto tr17;
@@ -321,28 +325,24 @@ case 7:
 	}
 	goto tr16;
 case 13:
-	switch( (*p) ) {
-		case 7: goto tr17;
-		case 27: goto tr18;
-	}
-	goto tr16;
+	goto tr1;
 case 8:
 	if ( (*p) == 92 )
-		goto tr19;
-	goto tr2;
-case 14:
-	goto tr2;
+		goto tr17;
+	goto tr1;
 case 9:
-	if ( (*p) == 27 )
-		goto tr2;
-	goto tr20;
-case 15:
-	goto tr2;
+	switch( (*p) ) {
+		case 7: goto tr1;
+		case 27: goto tr1;
+	}
+	goto tr19;
+case 14:
+	goto tr1;
 	}
 
-	tr2: cs = 0; goto f0;
+	tr1: cs = 0; goto f0;
 	tr0: cs = 1; goto f1;
-	tr1: cs = 2; goto _again;
+	tr2: cs = 2; goto _again;
 	tr3: cs = 3; goto _again;
 	tr4: cs = 4; goto _again;
 	tr11: cs = 6; goto f8;
@@ -360,7 +360,6 @@ case 15:
 	tr14: cs = 12; goto f11;
 	tr17: cs = 13; goto f14;
 	tr19: cs = 14; goto f15;
-	tr20: cs = 15; goto f16;
 
 	f0: _acts = _ansi_actions + 1; goto execFuncs;
 	f1: _acts = _ansi_actions + 3; goto execFuncs;
@@ -371,14 +370,13 @@ case 15:
 	f12: _acts = _ansi_actions + 13; goto execFuncs;
 	f4: _acts = _ansi_actions + 15; goto execFuncs;
 	f13: _acts = _ansi_actions + 17; goto execFuncs;
-	f15: _acts = _ansi_actions + 19; goto execFuncs;
+	f14: _acts = _ansi_actions + 19; goto execFuncs;
 	f7: _acts = _ansi_actions + 21; goto execFuncs;
 	f3: _acts = _ansi_actions + 23; goto execFuncs;
 	f6: _acts = _ansi_actions + 25; goto execFuncs;
 	f2: _acts = _ansi_actions + 27; goto execFuncs;
-	f16: _acts = _ansi_actions + 29; goto execFuncs;
+	f15: _acts = _ansi_actions + 29; goto execFuncs;
 	f11: _acts = _ansi_actions + 31; goto execFuncs;
-	f14: _acts = _ansi_actions + 34; goto execFuncs;
 
 execFuncs:
 	_nacts = *_acts++;
@@ -388,7 +386,7 @@ execFuncs:
 /* #line 185 "user/ansi_parser.rl" */
 	{
 			ansi_warn("Parser error.");
-			apars_handle_badseq();
+			apars_show_context();
 			inside_string = false; // no longer in string, for sure
 			{cs = 1;goto _again;}
 		}
@@ -444,7 +442,7 @@ execFuncs:
 	case 6:
 /* #line 234 "user/ansi_parser.rl" */
 	{
-			apars_handle_CSI(leadchar, arg, arg_cnt, (*p));
+			apars_handle_csi(leadchar, arg, arg_cnt, (*p));
 			{cs = 1;goto _again;}
 		}
 	break;
@@ -469,28 +467,28 @@ execFuncs:
 	{
 			inside_string = false;
 			string_buffer[str_ni++] = '\0';
-			apars_handle_StrCmd(leadchar, string_buffer);
+			apars_handle_string_cmd(leadchar, string_buffer);
 			{cs = 1;goto _again;}
 		}
 	break;
 	case 10:
 /* #line 270 "user/ansi_parser.rl" */
 	{
-			apars_handle_hashCode((*p));
+			apars_handle_hash_cmd((*p));
 			{cs = 1;goto _again;}
 		}
 	break;
 	case 11:
 /* #line 275 "user/ansi_parser.rl" */
 	{
-			apars_handle_shortCode((*p));
+			apars_handle_short_cmd((*p));
 			{cs = 1;goto _again;}
 		}
 	break;
 	case 12:
 /* #line 280 "user/ansi_parser.rl" */
 	{
-			apars_handle_spaceCmd((*p));
+			apars_handle_space_cmd((*p));
 			{cs = 1;goto _again;}
 		}
 	break;
@@ -504,11 +502,11 @@ execFuncs:
 	case 14:
 /* #line 292 "user/ansi_parser.rl" */
 	{
-			apars_handle_characterSet(leadchar, (*p));
+			apars_handle_chs_designate(leadchar, (*p));
 			{cs = 1;goto _again;}
 		}
 	break;
-/* #line 512 "user/ansi_parser.c" */
+/* #line 510 "user/ansi_parser.c" */
 		}
 	}
 	goto _again;
@@ -529,14 +527,14 @@ _again:
 /* #line 185 "user/ansi_parser.rl" */
 	{
 			ansi_warn("Parser error.");
-			apars_handle_badseq();
+			apars_show_context();
 			inside_string = false; // no longer in string, for sure
 			{cs = 1;	if ( p == pe )
 		goto _test_eof;
 goto _again;}
 		}
 	break;
-/* #line 540 "user/ansi_parser.c" */
+/* #line 538 "user/ansi_parser.c" */
 		}
 	}
 	}
diff --git a/user/ansi_parser.h b/user/ansi_parser.h
index 72a2bee..8e813bd 100644
--- a/user/ansi_parser.h
+++ b/user/ansi_parser.h
@@ -2,32 +2,11 @@
 #define ANSI_PARSER_H
 
 #include <stdlib.h>
-#include <screen.h>
-
-extern void apars_handle_plainchar(char c);
-extern void apars_handle_CSI(char leadchar, const int *params, int count, char keychar);
-extern void apars_handle_StrCmd(char leadchar, const char *buffer);
-extern void apars_handle_shortCode(char c);
-extern void apars_handle_hashCode(char c);
-extern void apars_handle_characterSet(char leadchar, char c);
-extern void apars_handle_spaceCmd(char c);
-extern void apars_reset_utf8buffer(void);
-extern void apars_handle_bel(void);
 
 void ansi_parser_reset(void);
 
 extern volatile u32 ansi_parser_char_cnt;
 
-// defined in the makefile
-#if DEBUG_ANSI
-#define ansi_warn warn
-#define ansi_dbg dbg
-#else
-#define ansi_warn(...)
-#define ansi_dbg(...)
-#endif
-
-
 /**
  * \brief Linear ANSI chars stream parser
  * 
@@ -43,6 +22,6 @@ extern volatile u32 ansi_parser_char_cnt;
 void ansi_parser(char newchar);
 
 /** This shows a short error message and prints the history (if any) */
-void apars_handle_badseq(void);
+void apars_show_context(void);
 
 #endif // ANSI_PARSER_H
diff --git a/user/ansi_parser.rl b/user/ansi_parser.rl
index 77b34a4..f0c9dd4 100644
--- a/user/ansi_parser.rl
+++ b/user/ansi_parser.rl
@@ -1,8 +1,8 @@
 #include <esp8266.h>
 #include "ansi_parser.h"
-#include "screen.h"
+#include "ansi_parser_callbacks.h"
 #include "ascii.h"
-#include "uart_driver.h"
+#include "apars_logging.h"
 
 /* Ragel constants block */
 %%{
@@ -37,7 +37,7 @@ static char history[HISTORY_LEN + 1];
 #endif
 
 void ICACHE_FLASH_ATTR
-apars_handle_badseq(void)
+apars_show_context(void)
 {
 #if DEBUG_ANSI
 	char buf1[HISTORY_LEN*3+2];
@@ -79,7 +79,6 @@ ansi_parser(char newchar)
 	static int  arg_ni;
 	static int  arg_cnt;
 	static int  arg[CSI_N_MAX];
-	static char csi_char;
 	static char string_buffer[STR_CHAR_MAX];
 	static int  str_ni;
 
@@ -124,15 +123,16 @@ ansi_parser(char newchar)
 				return;
 
 			case TAB:
-				screen_tab_forward(1);
+				apars_handle_tab();
 				return;
 
 				// Select G0 or G1
 			case SI:
-				screen_set_charset_n(1);
+				apars_handle_chs_switch(1);
 				return;
+
 			case SO:
-				screen_set_charset_n(0);
+				apars_handle_chs_switch(0);
 				return;
 
 			case BEL:
@@ -143,8 +143,8 @@ ansi_parser(char newchar)
 				}
 				break;
 
-			case ENQ: // respond with space (like xterm)
-				UART_WriteChar(UART0, SP, UART_TIMEOUT_US);
+			case ENQ:
+				apars_handle_enq();
 				return;
 
 				// Cancel the active sequence
@@ -176,15 +176,15 @@ ansi_parser(char newchar)
 	%%{
 #/*
 		ESC = 27;
-		NOESC = (any - ESC);
+		NOESC = (any - ESC - 7);
 		TOK_ST = ESC '\\'; # String terminator - used for OSC commands
-		STR_END = ('\a' | TOK_ST);
+		STR_END = (7 | TOK_ST);
 
 		# --- Error handler ---
 
 		action errBadSeq {
 			ansi_warn("Parser error.");
-			apars_handle_badseq();
+			apars_show_context();
 			inside_string = false; // no longer in string, for sure
 			fgoto main;
 		}
@@ -232,7 +232,7 @@ ansi_parser(char newchar)
 		}
 
 		action CSI_end {
-			apars_handle_CSI(leadchar, arg, arg_cnt, fc);
+			apars_handle_csi(leadchar, arg, arg_cnt, fc);
 			fgoto main;
 		}
 
@@ -247,7 +247,7 @@ ansi_parser(char newchar)
 			str_ni = 0;
 			string_buffer[0] = '\0';
 			inside_string = true;
-			fgoto StrCmd_body;
+			fgoto STRCMD_body;
 		}
 
 		action StrCmd_char {
@@ -257,28 +257,28 @@ ansi_parser(char newchar)
 		action StrCmd_end {
 			inside_string = false;
 			string_buffer[str_ni++] = '\0';
-			apars_handle_StrCmd(leadchar, string_buffer);
+			apars_handle_string_cmd(leadchar, string_buffer);
 			fgoto main;
 		}
 
 		# According to the spec, ESC should be allowed inside the string sequence.
 		# We disallow ESC for simplicity, as it's hardly ever used.
-		StrCmd_body := ((NOESC @StrCmd_char)* STR_END @StrCmd_end) $!errBadSeq;
+		STRCMD_body := ((NOESC @StrCmd_char)* STR_END @StrCmd_end) $!errBadSeq;
 
 		# --- Single character ESC ---
 
 		action HASH_code {
-			apars_handle_hashCode(fc);
+			apars_handle_hash_cmd(fc);
 			fgoto main;
 		}
 
 		action SHORT_code {
-			apars_handle_shortCode(fc);
+			apars_handle_short_cmd(fc);
 			fgoto main;
 		}
 
 		action SPACE_cmd {
-			apars_handle_spaceCmd(fc);
+			apars_handle_space_cmd(fc);
 			fgoto main;
 		}
 
@@ -290,7 +290,7 @@ ansi_parser(char newchar)
 		}
 
 		action CharsetCmd_end {
-			apars_handle_characterSet(leadchar, fc);
+			apars_handle_chs_designate(leadchar, fc);
 			fgoto main;
 		}
 
diff --git a/user/ansi_parser_callbacks.c b/user/ansi_parser_callbacks.c
index 30b32ec..35c9ea6 100644
--- a/user/ansi_parser_callbacks.c
+++ b/user/ansi_parser_callbacks.c
@@ -7,123 +7,18 @@
 #include <esp8266.h>
 #include <helpers.h>
 #include "ansi_parser_callbacks.h"
-#include "screen.h"
-#include "ansi_parser.h"
 #include "uart_driver.h"
-#include "sgr.h"
 #include "cgi_sockets.h"
-#include "ascii.h"
-#include "user_main.h"
-#include "syscfg.h"
-
-static char utf_collect[4];
-static int utf_i = 0;
-static int utf_j = 0;
-
-/**
- * Handle a received plain character
- * @param c - received character
- */
-void ICACHE_FLASH_ATTR
-apars_handle_plainchar(char c)
-{
-	// collecting unicode glyphs...
-	if (c & 0x80) {
-		if (utf_i == 0) {
-			// start
-			if (c == 192 || c == 193 || c >= 245) {
-				// forbidden codes
-				goto fail;
-			}
-
-			if ((c & 0xE0) == 0xC0) {
-				utf_i = 2;
-			}
-			else if ((c & 0xF0) == 0xE0) {
-				utf_i = 3;
-			}
-			else if ((c & 0xF8) == 0xF0) {
-				utf_i = 4;
-			}
-			else {
-				// chars over 127 that don't start unicode sequences
-				goto fail;
-			}
-
-			utf_collect[0] = c;
-			utf_j = 1;
-		}
-		else {
-			if ((c & 0xC0) != 0x80) {
-				goto fail;
-			}
-			else {
-				utf_collect[utf_j++] = c;
-				if (utf_j >= utf_i) {
-					screen_putchar(utf_collect);
-					apars_reset_utf8buffer();
-				}
-			}
-		}
-	}
-	else {
-		utf_collect[0] = c;
-		utf_collect[1] = 0; // just to make sure it's closed...
-		screen_putchar(utf_collect);
-	}
-
-	return;
-	fail:
-		ansi_warn("Bad UTF-8: %0Xh", c);
-	apars_reset_utf8buffer();
-}
-
-/**
- * Clear the buffer where we collect pieces of a code point.
- * This is used for parser reset.
- */
-void ICACHE_FLASH_ATTR
-apars_reset_utf8buffer(void)
-{
-	utf_i = 0;
-	utf_j = 0;
-	memset(utf_collect, 0, 4);
-}
+#include "version.h"
 
 /**
  * Send a response to UART0
  * @param str
  */
-static void ICACHE_FLASH_ATTR
-respond(const char *str)
-{
-	UART_WriteString(UART0, str, UART_TIMEOUT_US);
-}
-
-/**
- * Command to assign G0 or G1
- * @param leadchar - ( or ) for G0 or G1
- * @param c - character table ID (0, B etc)
- */
-void ICACHE_FLASH_ATTR
-apars_handle_characterSet(char leadchar, char c)
-{
-	if (leadchar == '(') screen_set_charset(0, c);
-	else if (leadchar == ')') screen_set_charset(1, c);
-	else {
-		ansi_warn("NOIMPL: ESC %c %c", leadchar, c);
-	}
-	// other alternatives * + . - / not implemented
-}
-
-/**
- * ESC SP <c> (this sets 8/7-bit mode and some other archaic options)
- * @param c - key character
- */
 void ICACHE_FLASH_ATTR
-apars_handle_spaceCmd(char c)
+apars_respond(const char *str)
 {
-	ansi_warn("NOIMPL: ESC SP %c", c);
+	UART_WriteString(UART0, str, UART_TIMEOUT_US);
 }
 
 /**
@@ -135,792 +30,18 @@ apars_handle_bel(void)
 	send_beep();
 }
 
-// data tables for the DECREPTPARM command response
-
-struct DECREPTPARM_parity {int parity; const char * msg;};
-static const struct DECREPTPARM_parity DECREPTPARM_parity_arr[] = {
-	{PARITY_NONE, "1"},
-	{PARITY_ODD, "4"},
-	{PARITY_EVEN, "5"},
-	{-1, 0}
-};
-
-struct DECREPTPARM_baud {int baud; const char * msg;};
-static const struct DECREPTPARM_baud DECREPTPARM_baud_arr[] = {
-	{BIT_RATE_300, "48"},
-	{BIT_RATE_600, "56"},
-	{BIT_RATE_1200, "64"},
-	{BIT_RATE_2400, "88"},
-	{BIT_RATE_4800, "96"},
-	{BIT_RATE_9600  , "104"},
-	{BIT_RATE_19200 , "112"},
-	{BIT_RATE_38400 , "120"},
-	{BIT_RATE_57600 , "128"}, // this is the last in the spec, follow +8
-	{BIT_RATE_74880 , "136"},
-	{BIT_RATE_115200, "144"},
-	{BIT_RATE_230400, "152"},
-	{BIT_RATE_460800, "160"},
-	{BIT_RATE_921600, "168"},
-	{BIT_RATE_1843200, "176"},
-	{BIT_RATE_3686400, "184"},
-	{-1, 0}
-};
-
 /**
- * Handle fully received CSI ANSI sequence
- * @param leadchar - private range leading character, 0 if none
- * @param params - array of CSI_N_MAX ints holding the numeric arguments
- * @param keychar - the char terminating the sequence
+ * Send to uart the answerback message
  */
 void ICACHE_FLASH_ATTR
-apars_handle_CSI(char leadchar, const int *params, int count, char keychar)
-{
-	int n1 = params[0];
-	int n2 = params[1];
-	int n3 = params[2];
-	char buf[32];
-	bool yn = false; // for ? l h
-
-	// defaults - FIXME this may inadvertently affect some variants that should be left unchanged
-	switch (keychar) {
-		case 'A': // move
-		case 'B':
-		case 'C':
-		case 'D':
-		case 'E':
-		case 'F':
-		case 'G': // set X
-		case '`':
-		case 'S': // scrolling
-		case 'T':
-		case 'X': // clear in line
-		case 'd': // set Y
-		case 'L':
-		case 'M':
-		case '@':
-		case 'P':
-		case 'I':
-		case 'Z':
-		case 'b':
-			if (n1 == 0) n1 = 1;
-			break;
-
-		case 'H':
-		case 'f':
-			if (n1 == 0) n1 = 1;
-			if (n2 == 0) n2 = 1;
-			break;
-
-		case 'J':
-		case 'K':
-			if (n1 > 2) n1 = 0;
-			break;
-
-		default:
-			// leave as is
-			break;
-	}
-
-	switch (keychar) {
-		// CUU CUD CUF CUB
-		case 'a':
-		case 'A': // Up
-			screen_cursor_move(-n1, 0, false);
-			break;
-
-		case 'e':
-		case 'B': // Down
-			screen_cursor_move(n1, 0, false);
-			break;
-
-		case 'C': // Right (forward)
-			screen_cursor_move(0, n1, false);
-			break;
-
-		case 'D': // Left (backward)
-			screen_cursor_move(0, -n1, false);
-			break;
-
-		case 'E': // CNL - Cursor Next Line
-			screen_cursor_move(n1, 0, false);
-			screen_cursor_set_x(0);
-			break;
-
-		case 'F': // CPL - Cursor Prev Line
-			screen_cursor_move(-n1, 0, false);
-			screen_cursor_set_x(0);
-			break;
-
-		case 'b':
-			// TODO repeat preceding graphic character n1 times
-			ansi_warn("NOIMPL: Repeat char");
-			return;
-
-			// Set X
-		case 'G':
-		case '`': // alternate code
-			screen_cursor_set_x(n1 - 1);
-			break; // 1-based
-
-			// Set Y
-		case 'd':
-			screen_cursor_set_y(n1 - 1);
-			break; // 1-based
-
-			// Clear in line
-		case 'X':
-			screen_clear_in_line(n1);
-			break; // 1-based
-
-			// SU, SD - scroll up/down
-		case 'S':
-			if (leadchar == NUL && count <= 1) {
-				screen_scroll_up(n1);
-			}
-			else {
-				// other:
-				// CSI ? Pi; Pa; Pv S (sixel)
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-		case 'T':
-			if (leadchar == NUL && count <= 1) {
-				// CSI Ps T
-				screen_scroll_down(n1);
-			}
-			else {
-				// other:
-				// CSI Ps ; Ps ; Ps ; Ps ; Ps T
-				// CSI > Ps; Ps T
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 't': // xterm window commands
-			if (leadchar == NUL && count <= 2) {
-				// CSI Ps ; Ps ; Ps t
-				switch (n1) {
-					case 8: // set size
-						screen_resize(n2, n3);
-						break;
-					case 18: // report size
-						printf(buf, "\033[8;%d;%dt", termconf_scratch.height, termconf_scratch.width);
-						respond(buf);
-						break;
-					case 11: // Report iconified -> is not iconified
-						respond("\033[1t");
-						break;
-					case 21: // Report title
-						respond("\033]L");
-						respond(termconf_scratch.title);
-						respond("\033\\");
-						break;
-					case 24: // Set Height only
-						screen_resize(n2, termconf_scratch.width);
-						break;
-					default:
-						ansi_warn("NOIMPL CSI %d t", n1);
-						break;
-				}
-			}
-			else {
-				// other:
-				// CSI > Ps; Ps t
-				// CSI Ps SP t,
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-			// CUP,HVP - set position
-		case 'H':
-		case 'f':
-			screen_cursor_set(n1-1, n2-1);
-			break; // 1-based
-
-		case 'J': // Erase screen
-			if (leadchar == '?') {
-				// TODO selective erase
-				ansi_warn("NOIMPL: Selective erase");
-			}
-
-			if (n1 == 0) {
-				screen_clear(CLEAR_FROM_CURSOR);
-			} else if (n1 == 1) {
-				screen_clear(CLEAR_TO_CURSOR);
-			} else {
-				screen_clear(CLEAR_ALL);
-				screen_cursor_set(0, 0);
-			}
-			break;
-
-		case 'K': // Erase lines
-			if (leadchar == '?') {
-				// TODO selective erase
-				ansi_warn("NOIMPL: Selective erase");
-			}
-
-			if (n1 == 0) {
-				screen_clear_line(CLEAR_FROM_CURSOR);
-			} else if (n1 == 1) {
-				screen_clear_line(CLEAR_TO_CURSOR);
-			} else {
-				screen_clear_line(CLEAR_ALL);
-			}
-			break;
-
-			// SCP, RCP - save/restore position
-		case 's':
-			if (leadchar == NUL && count == 0) {
-				screen_cursor_save(0);
-			}
-			else {
-				// other:
-				// CSI ? Pm s
-				// CSI Pl; Pr s
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 'u':
-			if (leadchar == NUL && count == 0) {
-				screen_cursor_restore(0);
-			}
-			else {
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 'n': // Queries
-			if (leadchar == '>') {
-				// some xterm garbage - discard
-				// CSI > Ps n
-				ansi_warn("NOIMPL: CSI > %d n", n1);
-				break;
-			}
-
-			if (n1 == 6) {
-				// Query cursor position
-				int x, y;
-				screen_cursor_get(&y, &x);
-				sprintf(buf, "\033[%d;%dR", y+1, x+1);
-				respond(buf);
-			}
-			else if (n1 == 5) {
-				// Query device status - reply "Device is OK"
-				respond("\033[0n");
-			}
-			else {
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 'h': // DEC feature enable
-			yn = 1;
-		case 'l': // DEC feature disable
-			// yn is 0 by default
-			for (int i = 0; i < count; i++) {
-				int n = params[i];
-				if (leadchar == '?') {
-					if (n == 1) {
-						screen_set_cursors_alt_mode(yn);
-					}
-					else if (n == 2) {
-						// should reset all Gx to USASCII and reset to VT100 (which we use always)
-						screen_set_charset(0, 'B');
-						screen_set_charset(1, 'B');
-					}
-					else if (n == 3) {
-						// TODO 132 column mode - not implemented due to RAM demands
-						ansi_warn("NOIMPL: 80->132");
-					}
-					else if (n == 4) {
-						// Smooth scroll - not implemented
-					}
-					else if (n == 5) {
-						screen_set_reverse_video(yn);
-					}
-					else if (n == 6) {
-						screen_set_origin_mode(yn);
-					}
-					else if (n == 7) {
-						screen_wrap_enable(yn);
-					}
-					else if (n == 8) {
-						// TODO Key auto-repeat
-						// We don't implement this currently, but it could be added
-						// - discard repeated keypress events between keydown and keyup.
-						ansi_warn("NOIMPL: Auto-repeat toggle");
-					}
-					else if (n == 9 || (n >= 1000 && n <= 1006)) {
-						// TODO mouse
-						// 1000 - C11 mouse - Send Mouse X & Y on button press and release.
-						// 1001 - Hilite mouse tracking
-						// 1002 - Cell Motion Mouse Tracking
-						// 1003 - All Motion Mouse Tracking
-						// 1004 - Send FocusIn/FocusOut events
-						// 1005 - Enable UTF-8 Mouse Mode
-						// 1006 - SGR mouse mode
-						ansi_warn("NOIMPL: Mouse tracking");
-					}
-					else if (n == 12) {
-						// TODO Cursor blink on/off
-						ansi_warn("NOIMPL: Cursor blink toggle");
-					}
-					else if (n == 40) {
-						// TODO allow/disallow 80->132 mode
-						// not implemented because of RAM demands
-						ansi_warn("NOIMPL: 80->132 enable");
-					}
-					else if (n == 47 || n == 1047) {
-						// Switch to/from alternate screen
-						//  - not implemented fully due to RAM demands
-						screen_swap_state(yn);
-					}
-					else if (n == 1048) {
-						// same as DECSC - save/restore cursor with attributes
-						if (yn) {
-							screen_cursor_save(true);
-						}
-						else {
-							screen_cursor_restore(true);
-						}
-					}
-					else if (n == 1049) {
-						// save/restore cursor and screen and clear it
-						if (yn) {
-							screen_cursor_save(true);
-							screen_swap_state(true); // this should save the screen - can't because of RAM size
-							screen_clear(CLEAR_ALL);
-						}
-						else {
-							screen_clear(CLEAR_ALL);
-							screen_swap_state(false); // this should restore the screen - can't because of RAM size
-							screen_cursor_restore(true);
-						}
-					}
-					else if (n >= 1050 && n <= 1053) {
-						// TODO Different kinds of function key emulation ?
-						// (In practice this seems hardly ever used)
-
-						// Ps = 1 0 5 0  -> Set terminfo/termcap function-key mode.
-						// Ps = 1 0 5 1  -> Set Sun function-key mode.
-						// Ps = 1 0 5 2  -> Set HP function-key mode.
-						// Ps = 1 0 5 3  -> Set SCO function-key mode.
-						ansi_warn("NOIMPL: FN key emul type");
-					}
-					else if (n == 2004) {
-						// Bracketed paste mode
-						// Discard, we don't implement this
-					}
-					else if (n == 25) {
-						screen_set_cursor_visible(yn);
-					}
-					else {
-						ansi_warn("NOIMPL: CSI ? %d %c", n, keychar);
-					}
-				}
-				else {
-					if (n == 4) {
-						screen_set_insert_mode(yn);
-					}
-					else if (n == 20) {
-						screen_set_newline_mode(yn);
-					}
-					else {
-						ansi_warn("NOIMPL: CSI %d %c", n, keychar);
-					}
-				}
-			}
-			break;
-
-		case 'm': // SGR - set graphics rendition
-			if (count == 0) {
-				count = 1; // this makes it work as 0 (reset)
-			}
-
-			if (leadchar == '>') {
-				// some xterm garbage - discard
-				// CSI > Ps; Ps m
-				break;
-			}
-
-			// iterate arguments
-			for (int i = 0; i < count; i++) {
-				int n = params[i];
-
-				if (n == SGR_RESET) screen_reset_sgr();
-				// -- set color --
-				else if (n >= SGR_FG_START && n <= SGR_FG_END) screen_set_fg((Color) (n - SGR_FG_START)); // ANSI normal fg
-				else if (n >= SGR_BG_START && n <= SGR_BG_END) screen_set_bg((Color) (n - SGR_BG_START)); // ANSI normal bg
-				else if (n == SGR_FG_DEFAULT) screen_set_fg(termconf_scratch.default_fg); // default fg
-				else if (n == SGR_BG_DEFAULT) screen_set_bg(termconf_scratch.default_bg); // default bg
-				// -- set attr --
-				else if (n == SGR_BOLD) screen_set_sgr(ATTR_BOLD, 1);
-				else if (n == SGR_FAINT) screen_set_sgr(ATTR_FAINT, 1);
-				else if (n == SGR_ITALIC) screen_set_sgr(ATTR_ITALIC, 1);
-				else if (n == SGR_UNDERLINE) screen_set_sgr(ATTR_UNDERLINE, 1);
-				else if (n == SGR_BLINK || n == SGR_BLINK_FAST) screen_set_sgr(ATTR_BLINK, 1); // 6 - rapid blink, not supported
-				else if (n == SGR_STRIKE) screen_set_sgr(ATTR_STRIKE, 1);
-				else if (n == SGR_FRAKTUR) screen_set_sgr(ATTR_FRAKTUR, 1);
-				else if (n == SGR_INVERSE) screen_set_sgr_inverse(1);
-				// -- clear attr --
-				else if (n == SGR_OFF(SGR_BOLD)) screen_set_sgr(ATTR_BOLD, 0);
-				else if (n == SGR_OFF(SGR_FAINT)) screen_set_sgr(ATTR_FAINT, 0);
-				else if (n == SGR_OFF(SGR_ITALIC)) screen_set_sgr(ATTR_ITALIC | ATTR_FRAKTUR, 0); // there is no dedicated OFF code for Fraktur
-				else if (n == SGR_OFF(SGR_UNDERLINE)) screen_set_sgr(ATTR_UNDERLINE, 0);
-				else if (n == SGR_OFF(SGR_BLINK)) screen_set_sgr(ATTR_BLINK, 0);
-				else if (n == SGR_OFF(SGR_STRIKE)) screen_set_sgr(ATTR_STRIKE, 0);
-				else if (n == SGR_OFF(SGR_INVERSE)) screen_set_sgr_inverse(0);
-				// -- AIX bright colors --
-				else if (n >= SGR_FG_BRT_START && n <= SGR_FG_BRT_END) screen_set_fg((Color) ((n - SGR_FG_BRT_START) + 8)); // AIX bright fg
-				else if (n >= SGR_BG_BRT_START && n <= SGR_BG_BRT_END) screen_set_bg((Color) ((n - SGR_BG_BRT_START) + 8)); // AIX bright bg
-				else {
-					ansi_warn("NOIMPL: SGR %d", n);
-				}
-			}
-			break;
-
-		case 'L': // Insert lines (shove down)
-			screen_insert_lines(n1);
-			break;
-
-		case 'M': // Delete lines (pull up)
-			screen_delete_lines(n1);
-			break;
-
-		case '@': // Insert in line (shove right)
-			screen_insert_characters(n1);
-			break;
-
-		case 'P': // Delete in line (pull left)
-			screen_delete_characters(n1);
-			break;
-
-		case 'r':
-			if (leadchar == NUL && count == 2) {
-				screen_set_scrolling_region(n1, n2);
-			}
-			else {
-				// other:
-				// CSI ? Pm r
-				// CSI Pt; Pl; Pb; Pr; Ps$ r
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 'g': // Clear tabs
-			if (n1 == 3) {
-				screen_clear_all_tabs();
-			} else {
-				screen_clear_tab();
-			}
-			break;
-
-		case 'Z': // Tab backward
-			screen_tab_reverse(n1);
-			break;
-
-		case 'I': // Tab forward
-			screen_tab_forward(n1);
-			break;
-
-		case 'c': // CSI-c - report capabilities
-			if (leadchar == NUL) {
-				respond("\033[?64;9c"); // pretend we're vt400 with national character sets
-			}
-			else if (leadchar == '>') {
-				 // 41 - we're "VT400", 0 - ROM cartridge number
-				sprintf(buf, "\033[>41;%d;0c", FIRMWARE_VERSION_NUM);
-				respond(buf);
-			} else {
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		case 'x': // DECREQTPARM -> DECREPTPARM
-			if (n1 <= 1) {
-				respond("\033[3;"); // this is a response on request (2 would be gratuitous)
-
-				// Parity
-				for(const struct DECREPTPARM_parity *p = DECREPTPARM_parity_arr; p->parity != -1; p++) {
-					if (p->parity == sysconf->uart_parity) {
-						respond(p->msg);
-						break;
-					}
-				}
-
-				// bits per character (uart byte)
-				respond(";8;");
-
-				// Baud rate
-				for(const struct DECREPTPARM_baud *p = DECREPTPARM_baud_arr; p->baud != -1; p++) {
-					if (p->baud == sysconf->uart_baudrate) {
-						respond(p->msg);
-						respond(";");
-						respond(p->msg);
-						break;
-					}
-				}
-
-				// multiplier 1, flags 0
-				respond(";1;0x"); // ROM cartridge number ??
-			}
-			break;
-
-		case 'p':
-			if (leadchar == '!') { // RIS
-				/* On real VT there are differences between soft and hard reset, we treat both equally */
-				screen_reset();
-			} else {
-				ansi_warn("NOIMPL: CSI");
-				apars_handle_badseq();
-			}
-			break;
-
-		default:
-			ansi_warn("NOIMPL: CSI Pm %c", keychar);
-			apars_handle_badseq();
-	}
-}
-
-/**
- * Codes in the format ESC # n
- * @param c - the trailing symbol (numeric ASCII)
- */
-void ICACHE_FLASH_ATTR apars_handle_hashCode(char c)
-{
-	switch(c) {
-		case '3': // Double size, top half
-		case '4': // Single size, bottom half
-		case '5': // Single width, single height
-		case '6': // Double width
-			ansi_warn("NOIMPL: Double Size Line");
-			break;
-
-		case '8':
-			screen_fill_with_E();
-			break;
-
-		default:
-			ansi_warn("NOIMPL: ESC # %c", c);
-	}
-}
-
-/**
- * Single-character escape codes (ESC x)
- * @param c - the trailing symbol (ASCII)
- */
-void ICACHE_FLASH_ATTR apars_handle_shortCode(char c)
-{
-	switch(c) {
-		case 'c': // screen reset
-			screen_reset();
-			break;
-
-		case '7': // save cursor + attributes
-			screen_cursor_save(true);
-			break;
-
-		case '8': // restore cursor + attributes
-			screen_cursor_restore(true);
-			break;
-
-		case 'E': // same as CR LF
-			screen_cursor_move(1, 0, false);
-			screen_cursor_set_x(0);
-			break;
-
-		case 'F': // bottom left
-			screen_cursor_set(termconf_scratch.height-1, 0);
-			break;
-
-		case 'D': // move cursor down, scroll screen up if needed
-			screen_cursor_move(1, 0, true);
-			break;
-
-		case 'M': // move cursor up, scroll screen down if needed
-			screen_cursor_move(-1, 0, true);
-			break;
-
-		case 'H':
-			screen_set_tab();
-			break;
-
-		case '>':
-			screen_set_numpad_alt_mode(false);
-			break;
-
-		case '<': // "Enter ANSI / VT100 mode" - no-op (we don't support VT52 mode)
-			break;
-
-		case '=':
-			screen_set_numpad_alt_mode(true);
-			break;
-
-		case '|': // Invoke the G3 Character Set as GR (LS3R).
-		case '}': // Invoke the G2 Character Set as GR (LS2R).
-		case '~': // Invoke the G1 Character Set as GR (LS1R).
-			// Those do not seem to do anything TODO investigate
-			break;
-
-		case '@': // no-op padding char (?)
-			break;
-
-		case '\\': // spurious string terminator
-			break;
-
-		default:
-			ansi_warn("NOIMPL: ESC %c", c);
-	}
-}
-
-/**
- * Helper function to set terminal title
- * @param str - title text
- */
-static void ICACHE_FLASH_ATTR
-set_title(const char *str)
-{
-	strncpy(termconf_scratch.title, str, TERM_TITLE_LEN);
-	screen_notifyChange(CHANGE_LABELS);
-}
-
-/**
- * Helper function to set terminal button label
- * @param num - button number 1-5
- * @param str - button text
- */
-static void ICACHE_FLASH_ATTR
-set_button_text(int num, const char *str)
-{
-	strncpy(termconf_scratch.btn[num-1], str, TERM_BTN_LEN);
-	screen_notifyChange(CHANGE_LABELS);
-}
-
-/**
- * Helper function to parse incoming OSC (Operating System Control)
- * @param buffer - the OSC body (after OSC and before ST)
- */
-static void ICACHE_FLASH_ATTR
-parse_osc(const char *buffer)
-{
-	const char *orig_buff = buffer;
-	int n = 0;
-	char c = 0;
-	while ((c = *buffer++) != 0) {
-		if (c >= '0' && c <= '9') {
-			n = (n * 10 + (c - '0'));
-		} else {
-			break;
-		}
-	}
-
-	if (c == ';') {
-		// Do something with the data string and number
-		// (based on xterm manpage)
-		if (n == 0 || n == 2) set_title(buffer);
-		else if (n >= 81 && n <= 85) { // numbers chosen to not collide with any xterm supported codes
-			set_button_text(n - 80, buffer);
-		}
-		else {
-			ansi_warn("NOIMPL: OSC %d ; %s ST", n, buffer);
-		}
-	}
-	else {
-		ansi_warn("BAD OSC: %s", orig_buff);
-	}
-}
-
-/**
- * Helper function to parse incoming DCS (Device Control String)
- * @param buffer - the DCS body (after DCS and before ST)
- */
-static void ICACHE_FLASH_ATTR
-parse_dcs(const char *buffer)
+apars_handle_enq(void)
 {
-	char buf[64]; // just about big enough for full-house SGR
-	size_t len = strlen(buffer);
-	if ((len == 3 || len == 4) && strneq(buffer, "$q", 2)) {
-		// DECRQSS - Request Status String
-		if (strneq(buffer+2, "\"p", 2)) {
-			// DECSCL - Select Conformance Level
-			respond("\033[P1$r64;1\"p\033\\"); // 64;1 - Pretend we are VT400 with 7-bit characters
-		}
-		else if (strneq(buffer+2, "\"q", 2)) {
-			// DECSCA - Select character protection attribute
-			sprintf(buf, "\033[P1$r%d\"q\033\\", 0); // 0 - Can erase - TODO real protection status if implemented
-			respond(buf);
-		}
-		else if (buffer[2] == 'r') {
-			// DECSTBM - Query scrolling region
-			sprintf(buf, "\033[P1$r%d;%dr\033\\", 1, termconf_scratch.height); // 1-80 TODO real extent of scrolling region
-			respond(buf);
-		}
-		else if (buffer[2] == 's') {
-			// DECSLRM - Query horizontal margins
-			sprintf(buf, "\033[P1$r%d;%ds\033\\", 1, termconf_scratch.width); // Can erase - TODO real extent of horiz margins if implemented
-			respond(buf);
-		}
-		else if (buffer[2] == 'm') {
-			// SGR - query SGR
-			respond("\033[P1$r");
-			screen_report_sgr(buf);
-			respond(buf);
-			respond("m\033\\");
-		}
-		else if (strneq(buffer+2, " q", 2)) {
-			// DECSCUSR - Query cursor style
-			sprintf(buf, "\033[P1$r%d q\033\\", 1);
-			/*
-				Ps = 0  -> blinking block.
-				Ps = 1  -> blinking block (default).
-				Ps = 2  -> steady block.
-				Ps = 3  -> blinking underline.
-				Ps = 4  -> steady underline.
-				Ps = 5  -> blinking bar (xterm).
-				Ps = 6  -> steady bar (xterm).
-			 */
-			respond(buf);
-		}
-		else {
-			// invalid query
-			ansi_warn("NOIMPL: DCS %s ST", buffer);
-			sprintf(buf, "\033[P0$r%s\033\\", buffer+2);
-		}
-	}
-	else {
-		ansi_warn("NOIMPL: DCS %s ST", buffer);
-	}
+	// version encased in SOS and ST
+	apars_respond("\x1bXESPTerm " FIRMWARE_VERSION "\x1b\\");
 }
 
 void ICACHE_FLASH_ATTR
-apars_handle_StrCmd(char leadchar, const char *buffer)
+apars_handle_tab(void)
 {
-	switch (leadchar) {
-		case 'k': // ESC k TITLE ST (defined in GNU screen manpage)
-			set_title(buffer);
-			break;
-		case ']': // OSC - Operating System Command
-			parse_osc(buffer);
-			break;
-		case 'P': // DCS - Device Control String
-			parse_dcs(buffer);
-			break;
-		case '^': // PM - Privacy Message
-			break;
-		case '_': // APC - Application Program Command
-			break;
-		case 'X': // SOS - Start of String (purpose unclear)
-			break;
-		default:
-			ansi_warn("NOIMPL: ESC %c Pt ST", leadchar);
-	}
+	screen_tab_forward(1);
 }
diff --git a/user/ansi_parser_callbacks.h b/user/ansi_parser_callbacks.h
index 971decf..0330641 100644
--- a/user/ansi_parser_callbacks.h
+++ b/user/ansi_parser_callbacks.h
@@ -1,16 +1,19 @@
 #ifndef ANSI_PARSER_CALLBACKS_H
 #define ANSI_PARSER_CALLBACKS_H
 
-#include "screen.h"
+#include "apars_csi.h"
+#include "apars_dcs.h"
+#include "apars_osc.h"
+#include "apars_string.h"
+#include "apars_short.h"
+#include "apars_utf8.h"
+
+void apars_respond(const char *str);
 
-void apars_handle_plainchar(char c);
-void apars_handle_CSI(char leadchar, const int *params, int count, char keychar);
-void apars_handle_StrCmd(char leadchar, const char *buffer);
-void apars_handle_shortCode(char c);
-void apars_handle_hashCode(char c);
-void apars_handle_characterSet(char leadchar, char c);
-void apars_handle_spaceCmd(char c);
-void apars_reset_utf8buffer(void);
 void apars_handle_bel(void);
+void apars_handle_enq(void);
+void apars_handle_tab(void);
+
+extern void apars_show_context(void);
 
 #endif //ESP_VT100_FIRMWARE_ANSI_PARSER_CALLBACKS_H
diff --git a/user/apars_csi.c b/user/apars_csi.c
new file mode 100644
index 0000000..0601d15
--- /dev/null
+++ b/user/apars_csi.c
@@ -0,0 +1,596 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// Handle CSI sequences
+// CSI <symbol?> Pm <symbol?> <char>
+// (CSI = ESC [)
+//
+// Example of those are cursor manipulation sequences and SGR.
+//
+// For details, see:
+// http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-Functions-using-CSI-_-ordered-by-the-final-character_s_
+//
+// Note:
+// not all sequences listed in the xterm manual are implemented, notably sequences with the trailing symbol,
+// graphic mode sequences, mouse reporting and complex multi-argument sequences that operate on regions.
+//
+// The screen size can be set using the xterm sequence: CSI Py ; Px t
+//
+
+#include <esp8266.h>
+#include "apars_csi.h"
+#include "screen.h"
+#include "apars_logging.h"
+#include "ansi_parser.h"
+#include "ascii.h"
+#include "ansi_parser_callbacks.h"
+#include "uart_driver.h"
+#include "sgr.h"
+#include "version.h"
+#include "syscfg.h"
+
+// TODO simplify file - split to subroutines
+
+// data tables for the DECREPTPARM command response
+
+struct DECREPTPARM_parity { int parity; const char * msg; };
+static const struct DECREPTPARM_parity DECREPTPARM_parity_arr[] = {
+	{PARITY_NONE, "1"},
+	{PARITY_ODD, "4"},
+	{PARITY_EVEN, "5"},
+	{-1, 0}
+};
+
+struct DECREPTPARM_baud { int baud; const char * msg; };
+static const struct DECREPTPARM_baud DECREPTPARM_baud_arr[] = {
+	{BIT_RATE_300, "48"},
+	{BIT_RATE_600, "56"},
+	{BIT_RATE_1200, "64"},
+	{BIT_RATE_2400, "88"},
+	{BIT_RATE_4800, "96"},
+	{BIT_RATE_9600  , "104"},
+	{BIT_RATE_19200 , "112"},
+	{BIT_RATE_38400 , "120"},
+	{BIT_RATE_57600 , "128"}, // this is the last in the spec, follow +8
+	{BIT_RATE_74880 , "136"},
+	{BIT_RATE_115200, "144"},
+	{BIT_RATE_230400, "152"},
+	{BIT_RATE_460800, "160"},
+	{BIT_RATE_921600, "168"},
+	{BIT_RATE_1843200, "176"},
+	{BIT_RATE_3686400, "184"},
+	{-1, 0}
+};
+
+static void warn_bad_csi()
+{
+	ansi_noimpl_r("Unknown CSI");
+	apars_show_context();
+}
+
+/**
+ * Handle fully received CSI ANSI sequence
+ * @param leadchar - private range leading character, 0 if none
+ * @param params - array of CSI_N_MAX ints holding the numeric arguments
+ * @param keychar - the char terminating the sequence
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_csi(char leadchar, const int *params, int count, char keychar)
+{
+	int n1 = params[0];
+	int n2 = params[1];
+	int n3 = params[2];
+	char buf[32];
+	bool yn = false; // for ? l h
+
+	// defaults - FIXME this may inadvertently affect some variants that should be left unchanged
+	switch (keychar) {
+		case 'A': // move
+		case 'B':
+		case 'C':
+		case 'D':
+		case 'E':
+		case 'F':
+		case 'G': // set X
+		case '`':
+		case 'S': // scrolling
+		case 'T':
+		case 'X': // clear in line
+		case 'd': // set Y
+		case 'L':
+		case 'M':
+		case '@':
+		case 'P':
+		case 'I':
+		case 'Z':
+		case 'b':
+			if (n1 == 0) n1 = 1;
+			break;
+
+		case 'H':
+		case 'f':
+			if (n1 == 0) n1 = 1;
+			if (n2 == 0) n2 = 1;
+			break;
+
+		case 'J':
+		case 'K':
+			if (n1 > 2) n1 = 0;
+			break;
+
+		default:
+			// leave as is
+			break;
+	}
+
+	switch (keychar) {
+		// CUU CUD CUF CUB
+		case 'a':
+		case 'A': // Up
+			screen_cursor_move(-n1, 0, false);
+			break;
+
+		case 'e':
+		case 'B': // Down
+			screen_cursor_move(n1, 0, false);
+			break;
+
+		case 'C': // Right (forward)
+			screen_cursor_move(0, n1, false);
+			break;
+
+		case 'D': // Left (backward)
+			screen_cursor_move(0, -n1, false);
+			break;
+
+		case 'E': // CNL - Cursor Next Line
+			screen_cursor_move(n1, 0, false);
+			screen_cursor_set_x(0);
+			break;
+
+		case 'F': // CPL - Cursor Prev Line
+			screen_cursor_move(-n1, 0, false);
+			screen_cursor_set_x(0);
+			break;
+
+		case 'b':
+			// TODO repeat preceding graphic character n1 times
+			ansi_noimpl("Repeat char");
+			return;
+
+			// Set X
+		case 'G':
+		case '`': // alternate code
+			screen_cursor_set_x(n1 - 1);
+			break; // 1-based
+
+			// Set Y
+		case 'd':
+			screen_cursor_set_y(n1 - 1);
+			break; // 1-based
+
+			// Clear in line
+		case 'X':
+			screen_clear_in_line(n1);
+			break; // 1-based
+
+			// SU, SD - scroll up/down
+		case 'S':
+			if (leadchar == NUL && count <= 1) {
+				screen_scroll_up(n1);
+			}
+			else {
+				// other:
+				// CSI ? Pi; Pa; Pv S (sixel)
+				warn_bad_csi();
+			}
+			break;
+
+		case 'T':
+			if (leadchar == NUL && count <= 1) {
+				// CSI Ps T
+				screen_scroll_down(n1);
+			}
+			else {
+				// other:
+				// CSI Ps ; Ps ; Ps ; Ps ; Ps T
+				// CSI > Ps; Ps T
+				warn_bad_csi();
+			}
+			break;
+
+		case 't': // xterm window commands
+			if (leadchar == NUL && count <= 2) {
+				// CSI Ps ; Ps ; Ps t
+				switch (n1) {
+					case 8: // set size
+						screen_resize(n2, n3);
+						break;
+					case 18: // report size
+						printf(buf, "\033[8;%d;%dt", termconf_scratch.height, termconf_scratch.width);
+						apars_respond(buf);
+						break;
+					case 11: // Report iconified -> is not iconified
+						apars_respond("\033[1t");
+						break;
+					case 21: // Report title
+						apars_respond("\033]L");
+						apars_respond(termconf_scratch.title);
+						apars_respond("\033\\");
+						break;
+					case 24: // Set Height only
+						screen_resize(n2, termconf_scratch.width);
+						break;
+					default:
+						ansi_noimpl("CSI %d t", n1);
+						break;
+				}
+			}
+			else {
+				// other:
+				// CSI > Ps; Ps t
+				// CSI Ps SP t,
+				warn_bad_csi();
+			}
+			break;
+
+			// CUP,HVP - set position
+		case 'H':
+		case 'f':
+			screen_cursor_set(n1-1, n2-1);
+			break; // 1-based
+
+		case 'J': // Erase screen
+			if (leadchar == '?') {
+				// TODO selective erase
+				ansi_noimpl("Selective erase");
+			}
+
+			if (n1 == 0) {
+				screen_clear(CLEAR_FROM_CURSOR);
+			} else if (n1 == 1) {
+				screen_clear(CLEAR_TO_CURSOR);
+			} else {
+				screen_clear(CLEAR_ALL);
+				screen_cursor_set(0, 0);
+			}
+			break;
+
+		case 'K': // Erase lines
+			if (leadchar == '?') {
+				// TODO selective erase
+				ansi_noimpl("Selective erase");
+			}
+
+			if (n1 == 0) {
+				screen_clear_line(CLEAR_FROM_CURSOR);
+			} else if (n1 == 1) {
+				screen_clear_line(CLEAR_TO_CURSOR);
+			} else {
+				screen_clear_line(CLEAR_ALL);
+			}
+			break;
+
+			// SCP, RCP - save/restore position
+		case 's':
+			if (leadchar == NUL && count == 0) {
+				screen_cursor_save(0);
+			}
+			else {
+				// other:
+				// CSI ? Pm s
+				// CSI Pl; Pr s
+				warn_bad_csi();
+			}
+			break;
+
+		case 'u':
+			if (leadchar == NUL && count == 0) {
+				screen_cursor_restore(0);
+			}
+			else {
+				warn_bad_csi();
+			}
+			break;
+
+		case 'n': // Queries
+			if (leadchar == '>') {
+				// some xterm garbage - discard
+				// CSI > Ps n
+				ansi_noimpl("CSI > %d n", n1);
+				break;
+			}
+
+			if (n1 == 6) {
+				// Query cursor position
+				int x, y;
+				screen_cursor_get(&y, &x);
+				sprintf(buf, "\033[%d;%dR", y+1, x+1);
+				apars_respond(buf);
+			}
+			else if (n1 == 5) {
+				// Query device status - reply "Device is OK"
+				apars_respond("\033[0n");
+			}
+			else {
+				warn_bad_csi();
+			}
+			break;
+
+		case 'h': // DEC feature enable
+			yn = 1;
+		case 'l': // DEC feature disable
+			// yn is 0 by default
+			for (int i = 0; i < count; i++) {
+				int n = params[i];
+				if (leadchar == '?') {
+					if (n == 1) {
+						screen_set_cursors_alt_mode(yn);
+					}
+					else if (n == 2) {
+						// should reset all Gx to USASCII and reset to VT100 (which we use always)
+						screen_set_charset(0, 'B');
+						screen_set_charset(1, 'B');
+					}
+					else if (n == 3) {
+						// 132 column mode - not implemented due to RAM demands
+//						ansi_noimpl("80->132");
+					}
+					else if (n == 4) {
+						// Smooth scroll - not implemented
+					}
+					else if (n == 5) {
+						screen_set_reverse_video(yn);
+					}
+					else if (n == 6) {
+						screen_set_origin_mode(yn);
+					}
+					else if (n == 7) {
+						screen_wrap_enable(yn);
+					}
+					else if (n == 8) {
+						// Key auto-repeat
+						// We don't implement this currently, but it could be added
+						// - discard repeated keypress events between keydown and keyup.
+//						ansi_noimpl("Auto-repeat toggle");
+					}
+					else if (n == 9 || (n >= 1000 && n <= 1006)) {
+						// TODO mouse
+						// 1000 - C11 mouse - Send Mouse X & Y on button press and release.
+						// 1001 - Hilite mouse tracking
+						// 1002 - Cell Motion Mouse Tracking
+						// 1003 - All Motion Mouse Tracking
+						// 1004 - Send FocusIn/FocusOut events
+						// 1005 - Enable UTF-8 Mouse Mode
+						// 1006 - SGR mouse mode
+						ansi_noimpl("Mouse tracking");
+					}
+					else if (n == 12) {
+						// TODO Cursor blink on/off
+						ansi_noimpl("Cursor blink toggle");
+					}
+					else if (n == 40) {
+						// allow/disallow 80->132 mode
+						// not implemented because of RAM demands
+						ansi_noimpl("80->132 enable");
+					}
+					else if (n == 45) {
+						// reverse wrap-around
+						ansi_noimpl("Reverse Wraparound");
+					}
+					else if (n == 69) {
+						// horizontal margins
+						ansi_noimpl("Left/right margin");
+					}
+					else if (n == 47 || n == 1047) {
+						// Switch to/from alternate screen
+						//  - not implemented fully due to RAM demands
+						screen_swap_state(yn);
+					}
+					else if (n == 1048) {
+						// same as DECSC - save/restore cursor with attributes
+						if (yn) {
+							screen_cursor_save(true);
+						}
+						else {
+							screen_cursor_restore(true);
+						}
+					}
+					else if (n == 1049) {
+						// save/restore cursor and screen and clear it
+						if (yn) {
+							screen_cursor_save(true);
+							screen_swap_state(true); // this should save the screen - can't because of RAM size
+							screen_clear(CLEAR_ALL);
+						}
+						else {
+							screen_clear(CLEAR_ALL);
+							screen_swap_state(false); // this should restore the screen - can't because of RAM size
+							screen_cursor_restore(true);
+						}
+					}
+					else if (n >= 1050 && n <= 1053) {
+						// TODO Different kinds of function key emulation ?
+						// (In practice this seems hardly ever used)
+
+						// Ps = 1 0 5 0  -> Set terminfo/termcap function-key mode.
+						// Ps = 1 0 5 1  -> Set Sun function-key mode.
+						// Ps = 1 0 5 2  -> Set HP function-key mode.
+						// Ps = 1 0 5 3  -> Set SCO function-key mode.
+						ansi_noimpl("FN key emul type");
+					}
+					else if (n == 2004) {
+						// Bracketed paste mode
+						// Discard, we don't implement this
+					}
+					else if (n == 25) {
+						screen_set_cursor_visible(yn);
+					}
+					else {
+						ansi_noimpl("CSI ? %d %c", n, keychar);
+					}
+				}
+				else {
+					if (n == 4) {
+						screen_set_insert_mode(yn);
+					}
+					else if (n == 20) {
+						screen_set_newline_mode(yn);
+					}
+					else {
+						ansi_noimpl("CSI %d %c", n, keychar);
+					}
+				}
+			}
+			break;
+
+		case 'm': // SGR - set graphics rendition
+			if (count == 0) {
+				count = 1; // this makes it work as 0 (reset)
+			}
+
+			if (leadchar == '>') {
+				// some xterm garbage - discard
+				// CSI > Ps; Ps m
+				break;
+			}
+
+			// iterate arguments
+			for (int i = 0; i < count; i++) {
+				int n = params[i];
+
+				if (n == SGR_RESET) screen_reset_sgr();
+					// -- set color --
+				else if (n >= SGR_FG_START && n <= SGR_FG_END) screen_set_fg((Color) (n - SGR_FG_START)); // ANSI normal fg
+				else if (n >= SGR_BG_START && n <= SGR_BG_END) screen_set_bg((Color) (n - SGR_BG_START)); // ANSI normal bg
+				else if (n == SGR_FG_DEFAULT) screen_set_fg(termconf_scratch.default_fg); // default fg
+				else if (n == SGR_BG_DEFAULT) screen_set_bg(termconf_scratch.default_bg); // default bg
+					// -- set attr --
+				else if (n == SGR_BOLD) screen_set_sgr(ATTR_BOLD, 1);
+				else if (n == SGR_FAINT) screen_set_sgr(ATTR_FAINT, 1);
+				else if (n == SGR_ITALIC) screen_set_sgr(ATTR_ITALIC, 1);
+				else if (n == SGR_UNDERLINE) screen_set_sgr(ATTR_UNDERLINE, 1);
+				else if (n == SGR_BLINK || n == SGR_BLINK_FAST) screen_set_sgr(ATTR_BLINK, 1); // 6 - rapid blink, not supported
+				else if (n == SGR_STRIKE) screen_set_sgr(ATTR_STRIKE, 1);
+				else if (n == SGR_FRAKTUR) screen_set_sgr(ATTR_FRAKTUR, 1);
+				else if (n == SGR_INVERSE) screen_set_sgr_inverse(1);
+					// -- clear attr --
+				else if (n == SGR_OFF(SGR_BOLD)) screen_set_sgr(ATTR_BOLD, 0);
+				else if (n == SGR_OFF(SGR_FAINT)) screen_set_sgr(ATTR_FAINT, 0);
+				else if (n == SGR_OFF(SGR_ITALIC)) screen_set_sgr(ATTR_ITALIC | ATTR_FRAKTUR, 0); // there is no dedicated OFF code for Fraktur
+				else if (n == SGR_OFF(SGR_UNDERLINE)) screen_set_sgr(ATTR_UNDERLINE, 0);
+				else if (n == SGR_OFF(SGR_BLINK)) screen_set_sgr(ATTR_BLINK, 0);
+				else if (n == SGR_OFF(SGR_STRIKE)) screen_set_sgr(ATTR_STRIKE, 0);
+				else if (n == SGR_OFF(SGR_INVERSE)) screen_set_sgr_inverse(0);
+					// -- AIX bright colors --
+				else if (n >= SGR_FG_BRT_START && n <= SGR_FG_BRT_END) screen_set_fg((Color) ((n - SGR_FG_BRT_START) + 8)); // AIX bright fg
+				else if (n >= SGR_BG_BRT_START && n <= SGR_BG_BRT_END) screen_set_bg((Color) ((n - SGR_BG_BRT_START) + 8)); // AIX bright bg
+				else {
+					ansi_noimpl("SGR %d", n);
+				}
+			}
+			break;
+
+		case 'L': // Insert lines (shove down)
+			screen_insert_lines(n1);
+			break;
+
+		case 'M': // Delete lines (pull up)
+			screen_delete_lines(n1);
+			break;
+
+		case '@': // Insert in line (shove right)
+			screen_insert_characters(n1);
+			break;
+
+		case 'P': // Delete in line (pull left)
+			screen_delete_characters(n1);
+			break;
+
+		case 'r':
+			if (leadchar == NUL && (count == 2 || count == 0)) {
+				screen_set_scrolling_region(n1, n2);
+			}
+			else {
+				// other:
+				// CSI ? Pm r
+				// CSI Pt; Pl; Pb; Pr; Ps$ r
+				warn_bad_csi();
+			}
+			break;
+
+		case 'g': // Clear tabs
+			if (n1 == 3) {
+				screen_clear_all_tabs();
+			} else {
+				screen_clear_tab();
+			}
+			break;
+
+		case 'Z': // Tab backward
+			screen_tab_reverse(n1);
+			break;
+
+		case 'I': // Tab forward
+			screen_tab_forward(n1);
+			break;
+
+		case 'c': // CSI-c - report capabilities
+			if (leadchar == NUL) {
+				apars_respond("\033[?64;9c"); // pretend we're vt400 with national character sets
+			}
+			else if (leadchar == '>') {
+				// 41 - we're "VT400", 0 - ROM cartridge number
+				sprintf(buf, "\033[>41;%d;0c", FIRMWARE_VERSION_NUM);
+				apars_respond(buf);
+			} else {
+				warn_bad_csi();
+			}
+			break;
+
+		case 'x': // DECREQTPARM -> DECREPTPARM
+			// reference http://vt100.net/docs/vt100-ug/chapter3.html - search DECREPTPARM
+			if (n1 <= 1) {
+				apars_respond("\033["); // this is a response on request (2 would be gratuitous)
+
+				apars_respond(n1 == 0 ? "2;" : "3;");
+
+				// Parity
+				for(const struct DECREPTPARM_parity *p = DECREPTPARM_parity_arr; p->parity != -1; p++) {
+					if (p->parity == sysconf->uart_parity) {
+						apars_respond(p->msg);
+						break;
+					}
+				}
+
+				// bits per character (uart byte) - 1 = 8, 2 = 7
+				apars_respond(";1;");
+
+				// Baud rate
+				for(const struct DECREPTPARM_baud *p = DECREPTPARM_baud_arr; p->baud != -1; p++) {
+					if (p->baud == sysconf->uart_baudrate) {
+						apars_respond(p->msg);
+						apars_respond(";");
+						apars_respond(p->msg);
+						break;
+					}
+				}
+
+				// multiplier 1, flags 0
+				apars_respond(";1;0x"); // ROM cartridge number ??
+			}
+			break;
+
+		case 'p':
+			if (leadchar == '!') { // RIS
+				/* On real VT there are differences between soft and hard reset, we treat both equally */
+				screen_reset();
+			} else {
+				warn_bad_csi();
+			}
+			break;
+
+		default:
+			warn_bad_csi();
+	}
+}
diff --git a/user/apars_csi.h b/user/apars_csi.h
new file mode 100644
index 0000000..cbd0a72
--- /dev/null
+++ b/user/apars_csi.h
@@ -0,0 +1,10 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_CSI_H
+#define ESP_VT100_FIRMWARE_APARS_CSI_H
+
+void apars_handle_csi(char leadchar, const int *params, int count, char keychar);
+
+#endif //ESP_VT100_FIRMWARE_APARS_CSI_H
diff --git a/user/apars_dcs.c b/user/apars_dcs.c
new file mode 100644
index 0000000..a454d5e
--- /dev/null
+++ b/user/apars_dcs.c
@@ -0,0 +1,89 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// Handle DCS sequences (Device Control String)
+// DCS Pt ST
+// (DCS = ESC P)
+//
+// Those are used for terminal status queries.
+//
+// Pt =
+// $ q " p .... read conformance level
+// $ q " q .... read character protection attribute
+// $ q r ...... read scrolling region extents
+// $ q s ...... read horizontal margins extents
+// $ q m ...... read SGR in a format that would restore them exactly when run as a CSI Pm m
+// $ q SP q ... read cursor style
+//
+// For details, see
+// http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-Device-Control-functions
+//
+
+#include <esp8266.h>
+#include "apars_dcs.h"
+#include "ansi_parser_callbacks.h"
+#include "screen.h"
+#include "apars_logging.h"
+
+/**
+ * Helper function to parse incoming DCS (Device Control String)
+ * @param buffer - the DCS body (after DCS and before ST)
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_dcs(const char *buffer)
+{
+	char buf[64]; // just about big enough for full-house SGR
+	size_t len = strlen(buffer);
+	if ((len == 3 || len == 4) && strneq(buffer, "$q", 2)) {
+		// DECRQSS - Request Status String
+		if (strneq(buffer+2, "\"p", 2)) {
+			// DECSCL - Select Conformance Level
+			apars_respond("\033P1$r64;1\"p\033\\"); // 64;1 - Pretend we are VT400 with 7-bit characters
+		}
+		else if (strneq(buffer+2, "\"q", 2)) {
+			// DECSCA - Select character protection attribute
+			sprintf(buf, "\033P1$r%d\"q\033\\", 0); // 0 - Can erase - TODO real protection status if implemented
+			apars_respond(buf);
+		}
+		else if (buffer[2] == 'r') {
+			// DECSTBM - Query scrolling region
+			sprintf(buf, "\033P1$r%d;%dr\033\\", 1, termconf_scratch.height); // 1-80 TODO real extent of scrolling region
+			apars_respond(buf);
+		}
+		else if (buffer[2] == 's') {
+			// DECSLRM - Query horizontal margins
+			sprintf(buf, "\033P1$r%d;%ds\033\\", 1, termconf_scratch.width); // Can erase - TODO real extent of horiz margins if implemented
+			apars_respond(buf);
+		}
+		else if (buffer[2] == 'm') {
+			// SGR - query SGR
+			apars_respond("\033P1$r");
+			screen_report_sgr(buf);
+			apars_respond(buf);
+			apars_respond("m\033\\");
+		}
+		else if (strneq(buffer+2, " q", 2)) {
+			// DECSCUSR - Query cursor style
+			sprintf(buf, "\033P1$r%d q\033\\", 1);
+			/*
+				Ps = 0  -> blinking block.
+				Ps = 1  -> blinking block (default).
+				Ps = 2  -> steady block.
+				Ps = 3  -> blinking underline.
+				Ps = 4  -> steady underline.
+				Ps = 5  -> blinking bar (xterm).
+				Ps = 6  -> steady bar (xterm).
+			 */
+			apars_respond(buf);
+		}
+		else {
+			// invalid query
+			ansi_noimpl("DCS %s ST", buffer);
+			sprintf(buf, "\033P0$r%s\033\\", buffer+2);
+		}
+	}
+	else {
+		ansi_warn("Bad DCS: %s", buffer);
+		apars_show_context();
+	}
+}
diff --git a/user/apars_dcs.h b/user/apars_dcs.h
new file mode 100644
index 0000000..f9d4ad7
--- /dev/null
+++ b/user/apars_dcs.h
@@ -0,0 +1,10 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_DCS_H
+#define ESP_VT100_FIRMWARE_APARS_DCS_H
+
+void apars_handle_dcs(const char *buffer);
+
+#endif //ESP_VT100_FIRMWARE_APARS_DCS_H
diff --git a/user/apars_logging.h b/user/apars_logging.h
new file mode 100644
index 0000000..a4bd0f4
--- /dev/null
+++ b/user/apars_logging.h
@@ -0,0 +1,29 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// Logging functions for the parser, can be switched off with a compile flag
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_LOGGING_H
+#define ESP_VT100_FIRMWARE_APARS_LOGGING_H
+
+#include <esp8266.h>
+
+// defined in the makefile
+#if DEBUG_ANSI
+#define ansi_warn warn
+#define ansi_dbg dbg
+#else
+#define ansi_warn(...)
+#define ansi_dbg(...)
+#endif
+
+#if DEBUG_ANSI_NOIMPL
+#define ansi_noimpl(fmt, ...) warn("NOIMPL: " fmt, ##__VA_ARGS__)
+#define ansi_noimpl_r(fmt, ...) warn(fmt, ##__VA_ARGS__)
+#else
+#define ansi_noimpl(fmt, ...)
+#define ansi_noimpl_r(fmt, ...)
+#endif
+
+#endif //ESP_VT100_FIRMWARE_APARS_LOGGING_H
diff --git a/user/apars_osc.c b/user/apars_osc.c
new file mode 100644
index 0000000..18f9855
--- /dev/null
+++ b/user/apars_osc.c
@@ -0,0 +1,65 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// Handle OSC commands (Operating System Command)
+// ESC ] Ps ; Pt ST
+//
+// Those are used to pass various text variables to the terminal:
+//
+// Ps = 0 or 2 ... set screen title to Pt
+// Ps = 81-85  ... set button label to Pt
+//
+
+#include "apars_osc.h"
+#include "apars_logging.h"
+#include "screen.h"
+#include "ansi_parser.h"
+
+/**
+ * Helper function to set terminal button label
+ * @param num - button number 1-5
+ * @param str - button text
+ */
+static void ICACHE_FLASH_ATTR
+set_button_text(int num, const char *str)
+{
+	strncpy(termconf_scratch.btn[num-1], str, TERM_BTN_LEN);
+	screen_notifyChange(CHANGE_LABELS);
+}
+
+/**
+ * Helper function to parse incoming OSC (Operating System Control)
+ * @param buffer - the OSC body (after OSC and before ST)
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_osc(const char *buffer)
+{
+	const char *orig_buff = buffer;
+	int n = 0;
+	char c = 0;
+	while ((c = *buffer++) != 0) {
+		if (c >= '0' && c <= '9') {
+			n = (n * 10 + (c - '0'));
+		} else {
+			break;
+		}
+	}
+
+	if (c == ';') {
+		// Do something with the data string and number
+		// (based on xterm manpage)
+		if (n == 0 || n == 2) {
+			screen_set_title(buffer);
+		}
+		else if (n >= 81 && n <= 85) { // numbers chosen to not collide with any xterm supported codes
+			set_button_text(n - 80, buffer);
+		}
+		else {
+			ansi_noimpl("OSC %d ; %s ST", n, buffer);
+		}
+	}
+	else {
+		ansi_warn("BAD OSC: %s", orig_buff);
+		apars_show_context();
+	}
+}
diff --git a/user/apars_osc.h b/user/apars_osc.h
new file mode 100644
index 0000000..cd2c96f
--- /dev/null
+++ b/user/apars_osc.h
@@ -0,0 +1,10 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_OSC_H
+#define ESP_VT100_FIRMWARE_APARS_OSC_H
+
+void apars_handle_osc(const char *buffer);
+
+#endif //ESP_VT100_FIRMWARE_APARS_OSC_H
diff --git a/user/apars_short.c b/user/apars_short.c
new file mode 100644
index 0000000..329c40d
--- /dev/null
+++ b/user/apars_short.c
@@ -0,0 +1,179 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// Short sequences: (* = not implemented)
+//
+// ESC char
+//   ESC 6     Back Index (DECBI), VT420 and up.
+//   ESC 7     Save Cursor (DECSC).
+//   ESC 8     Restore Cursor (DECRC).
+//   ESC 9     Forward Index (DECFI), VT420 and up.
+//   ESC =     Application Keypad (DECKPAM).
+//   ESC >     Normal Keypad (DECKPNM).
+//   ESC F     Cursor to lower left corner of screen.
+//   ESC c     Full Reset (RIS).
+//  *ESC l     Memory Lock (per HP terminals). Locks memory above the cursor.
+//  *ESC m     Memory Unlock (per HP terminals).
+//   ESC n     Invoke the G2 Character Set as GL (LS2).
+//   ESC o     Invoke the G3 Character Set as GL (LS3).
+//  *ESC |     Invoke the G3 Character Set as GR (LS3R).
+//  *ESC }     Invoke the G2 Character Set as GR (LS2R).
+//  *ESC ~     Invoke the G1 Character Set as GR (LS1R).
+//
+// ESC # Ps
+//  *ESC # 3   DEC double-height line, top half (DECDHL).
+//  *ESC # 4   DEC double-height line, bottom half (DECDHL).
+//  *ESC # 5   DEC single-width line (DECSWL).
+//  *ESC # 6   DEC double-width line (DECDWL).
+//   ESC # 8   DEC Screen Alignment Test (DECALN).
+//
+// ESC SP char
+//  *ESC SP F  7-bit controls (S7C1T).
+//  *ESC SP G  8-bit controls (S8C1T).
+//  *ESC SP L  Set ANSI conformance level 1 (dpANS X3.134.1).
+//  *ESC SP M  Set ANSI conformance level 2 (dpANS X3.134.1).
+//  *ESC SP N  Set ANSI conformance level 3 (dpANS X3.134.1).
+//
+// Charset commands
+//   ESC ( char  Designate G0 character set ('0' = symbols, 'B' = ASCII-US, 'A' = ASCII-UK)
+//   ESC ) char  Designate G1 character set
+//   SO          Switch to G0 character set
+//   SI          Switch to G1 character set
+//
+
+#include <esp8266.h>
+#include "apars_short.h"
+#include "apars_logging.h"
+#include "screen.h"
+
+// ----- Character Set ---
+
+/**
+ * Command to assign G0 or G1
+ * @param slot - ( or ) for G0 or G1
+ * @param c - character table ID (0, B etc)
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_chs_designate(char slot, char c)
+{
+	if (slot == '(') screen_set_charset(0, c); // G0
+	else if (slot == ')') screen_set_charset(1, c); // G1
+	else {
+		ansi_noimpl("ESC %c %c", slot, c);
+	}
+	// other alternatives * + . - / not implemented
+}
+
+/** Select charset slot */
+void ICACHE_FLASH_ATTR
+apars_handle_chs_switch(int Gx)
+{
+	screen_set_charset_n(Gx);
+}
+
+// ----- ESC SP char -----
+
+/**
+ * ESC SP <c> (this sets 8/7-bit mode and some other archaic options)
+ * @param c - key character
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_space_cmd(char c)
+{
+	ansi_noimpl("ESC SP %c", c);
+}
+
+// ----- ESC # num -----
+
+/**
+ * Codes in the format ESC # n
+ * @param c - the trailing symbol (numeric ASCII)
+ */
+void ICACHE_FLASH_ATTR apars_handle_hash_cmd(char c)
+{
+	switch(c) {
+		case '3': // Double size, top half
+		case '4': // Single size, bottom half
+		case '5': // Single width, single height
+		case '6': // Double width
+			ansi_noimpl("Double Size Line");
+			break;
+
+		case '8':
+			screen_fill_with_E();
+			break;
+
+		default:
+			ansi_noimpl("ESC # %c", c);
+	}
+}
+
+// ----- ESC char -----
+
+/**
+ * Single-character escape codes (ESC x)
+ * @param c - the trailing symbol (ASCII)
+ */
+void ICACHE_FLASH_ATTR apars_handle_short_cmd(char c)
+{
+	switch(c) {
+		case 'c': // screen reset
+			screen_reset();
+			break;
+
+		case '7': // save cursor + attributes
+			screen_cursor_save(true);
+			break;
+
+		case '8': // restore cursor + attributes
+			screen_cursor_restore(true);
+			break;
+
+		case 'E': // same as CR LF
+			screen_cursor_move(1, 0, false);
+			screen_cursor_set_x(0);
+			break;
+
+		case 'F': // bottom left
+			screen_cursor_set(termconf_scratch.height-1, 0);
+			break;
+
+		case 'D': // move cursor down, scroll screen up if needed
+			screen_cursor_move(1, 0, true);
+			break;
+
+		case 'M': // move cursor up, scroll screen down if needed
+			screen_cursor_move(-1, 0, true);
+			break;
+
+		case 'H':
+			screen_set_tab();
+			break;
+
+		case '>':
+			screen_set_numpad_alt_mode(false);
+			break;
+
+		case '<': // "Enter ANSI / VT100 mode" - no-op (we don't support VT52 mode)
+			break;
+
+		case '=':
+			screen_set_numpad_alt_mode(true);
+			break;
+
+		case '|': // Invoke the G3 Character Set as GR (LS3R).
+		case '}': // Invoke the G2 Character Set as GR (LS2R).
+		case '~': // Invoke the G1 Character Set as GR (LS1R).
+			// Those do not seem to do anything TODO investigate
+			break;
+
+		case '@': // no-op padding char (?)
+			break;
+
+		case '\\': // spurious string terminator
+			break;
+
+		default:
+			ansi_noimpl("ESC %c", c);
+	}
+}
diff --git a/user/apars_short.h b/user/apars_short.h
new file mode 100644
index 0000000..2616862
--- /dev/null
+++ b/user/apars_short.h
@@ -0,0 +1,14 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_SIMPLE_H
+#define ESP_VT100_FIRMWARE_APARS_SIMPLE_H
+
+void apars_handle_short_cmd(char c);
+void apars_handle_hash_cmd(char c);
+void apars_handle_space_cmd(char c);
+void apars_handle_chs_designate(char slot, char c);
+void apars_handle_chs_switch(int Gx);
+
+#endif //ESP_VT100_FIRMWARE_APARS_SIMPLE_H
diff --git a/user/apars_string.c b/user/apars_string.c
new file mode 100644
index 0000000..08de067
--- /dev/null
+++ b/user/apars_string.c
@@ -0,0 +1,52 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// String based commands.
+// Those command start with a introducer sequence, followed by arbitrary string,
+// and end with a String Terminator (`ESC \`, or `BEL`)
+//
+// ESC k Pt ST ... set screen title (same as `OSC 0 ; Pt ST`, is shorter)
+// ESC ] Pt ST ... OSC - Operating System Command (split to its own file)
+// ESC P Pt ST ... DCS - Device Control String (split to its own file)
+// ESC ^ Pt ST ... PM - Privacy message (unused)
+// ESC _ Pt ST ... APC - Application Program Command (unused)
+// ESC X Pt ST ... SOS - Start Of String (unused; sent back in response to ENQ)
+
+#include <esp8266.h>
+#include "apars_string.h"
+#include "apars_logging.h"
+#include "ansi_parser_callbacks.h"
+#include "screen.h"
+
+// ----- Generic String cmd - disambiguation -----
+
+void ICACHE_FLASH_ATTR
+apars_handle_string_cmd(char leadchar, const char *buffer)
+{
+	switch (leadchar) {
+		case 'k': // ESC k TITLE ST (defined in GNU screen manpage)
+			screen_set_title(buffer);
+			break;
+
+		case ']': // OSC - Operating System Command
+			apars_handle_osc(buffer);
+			break;
+
+		case 'P': // DCS - Device Control String
+			apars_handle_dcs(buffer);
+			break;
+
+		case '^': // PM - Privacy Message
+			break;
+
+		case '_': // APC - Application Program Command
+			break;
+
+		case 'X': // SOS - Start of String (purpose unclear)
+			break;
+
+		default:
+			ansi_warn("Bad str cmd");
+			apars_show_context();
+	}
+}
diff --git a/user/apars_string.h b/user/apars_string.h
new file mode 100644
index 0000000..1305905
--- /dev/null
+++ b/user/apars_string.h
@@ -0,0 +1,10 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_STRING_H
+#define ESP_VT100_FIRMWARE_APARS_STRING_H
+
+void apars_handle_string_cmd(char leadchar, const char *buffer);
+
+#endif //ESP_VT100_FIRMWARE_APARS_STRING_H
diff --git a/user/apars_utf8.c b/user/apars_utf8.c
new file mode 100644
index 0000000..a01a16b
--- /dev/null
+++ b/user/apars_utf8.c
@@ -0,0 +1,84 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+// UTF-8 parser - collects bytes of a code point before writing them
+// into a screen cell.
+//
+
+#include "apars_utf8.h"
+#include "apars_logging.h"
+#include "screen.h"
+
+static char utf_collect[4];
+static int utf_i = 0;
+static int utf_j = 0;
+
+/**
+ * Clear the buffer where we collect pieces of a code point.
+ * This is used for parser reset.
+ */
+void ICACHE_FLASH_ATTR
+apars_reset_utf8buffer(void)
+{
+	utf_i = 0;
+	utf_j = 0;
+	memset(utf_collect, 0, 4);
+}
+
+/**
+ * Handle a received plain character
+ * @param c - received character
+ */
+void ICACHE_FLASH_ATTR
+apars_handle_plainchar(char c)
+{
+	// collecting unicode glyphs...
+	if (c & 0x80) {
+		if (utf_i == 0) {
+			// start
+			if (c == 192 || c == 193 || c >= 245) {
+				// forbidden codes
+				goto fail;
+			}
+
+			if ((c & 0xE0) == 0xC0) {
+				utf_i = 2;
+			}
+			else if ((c & 0xF0) == 0xE0) {
+				utf_i = 3;
+			}
+			else if ((c & 0xF8) == 0xF0) {
+				utf_i = 4;
+			}
+			else {
+				// chars over 127 that don't start unicode sequences
+				goto fail;
+			}
+
+			utf_collect[0] = c;
+			utf_j = 1;
+		}
+		else {
+			if ((c & 0xC0) != 0x80) {
+				goto fail;
+			}
+			else {
+				utf_collect[utf_j++] = c;
+				if (utf_j >= utf_i) {
+					screen_putchar(utf_collect);
+					apars_reset_utf8buffer();
+				}
+			}
+		}
+	}
+	else {
+		utf_collect[0] = c;
+		utf_collect[1] = 0; // just to make sure it's closed...
+		screen_putchar(utf_collect);
+	}
+
+	return;
+	fail:
+	ansi_warn("Bad UTF-8: %0Xh", c);
+	apars_reset_utf8buffer();
+}
diff --git a/user/apars_utf8.h b/user/apars_utf8.h
new file mode 100644
index 0000000..06b0a85
--- /dev/null
+++ b/user/apars_utf8.h
@@ -0,0 +1,11 @@
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_APARS_UTF8_H
+#define ESP_VT100_FIRMWARE_APARS_UTF8_H
+
+void apars_handle_plainchar(char c);
+void apars_reset_utf8buffer(void);
+
+#endif //ESP_VT100_FIRMWARE_APARS_UTF8_H
diff --git a/user/cgi_main.c b/user/cgi_main.c
index 3c03368..32a885d 100644
--- a/user/cgi_main.c
+++ b/user/cgi_main.c
@@ -5,7 +5,7 @@
 
 #include "cgi_main.h"
 #include "screen.h"
-#include "user_main.h"
+#include "version.h"
 #include "helpers.h"
 
 /**
diff --git a/user/screen.c b/user/screen.c
index 83e6bc3..ea5c2de 100644
--- a/user/screen.c
+++ b/user/screen.c
@@ -566,6 +566,13 @@ screen_resize(int rows, int cols)
 	NOTIFY_DONE();
 }
 
+void ICACHE_FLASH_ATTR
+screen_set_title(const char *title)
+{
+	strncpy(termconf_scratch.title, title, TERM_TITLE_LEN);
+	screen_notifyChange(CHANGE_LABELS);
+}
+
 /**
  * Shift screen upwards
  */
@@ -626,6 +633,13 @@ void ICACHE_FLASH_ATTR
 screen_set_scrolling_region(int from, int to)
 {
 	// TODO implement (also add to scr)
+	if (from == 0 && to == 0) {
+		// whole screen
+	} else if (from > 1 && from < H-1 && to > from) {
+		// set range
+	} else {
+		// Bad range, do nothing
+	}
 }
 
 //endregion
diff --git a/user/screen.h b/user/screen.h
index 4f4d75e..b918e24 100644
--- a/user/screen.h
+++ b/user/screen.h
@@ -85,6 +85,10 @@ void terminal_apply_settings_noclear(void);
 void screen_init(void);
 /** Change the screen size */
 void screen_resize(int rows, int cols);
+/** Set screen title */
+void screen_set_title(const char *title);
+/** Set a button text */
+void screen_set_button_text(int num, const char *text);
 
 // --- Encoding ---
 
diff --git a/user/user_main.c b/user/user_main.c
index 248db2a..c11ec8b 100644
--- a/user/user_main.c
+++ b/user/user_main.c
@@ -23,7 +23,7 @@
 #include "io.h"
 #include "screen.h"
 #include "routes.h"
-#include "user_main.h"
+#include "version.h"
 #include "uart_driver.h"
 #include "ansi_parser_callbacks.h"
 #include "wifimgr.h"
diff --git a/user/user_main.h b/user/version.h
similarity index 68%
rename from user/user_main.h
rename to user/version.h
index 8067be5..8343948 100644
--- a/user/user_main.h
+++ b/user/version.h
@@ -1,5 +1,9 @@
-#ifndef USER_MAIN_H_H
-#define USER_MAIN_H_H
+//
+// Created by MightyPork on 2017/08/20.
+//
+
+#ifndef ESP_VT100_FIRMWARE_VERSION_H
+#define ESP_VT100_FIRMWARE_VERSION_H
 
 #define FW_V_MAJOR 0
 #define FW_V_MINOR 6
@@ -9,4 +13,4 @@
 #define FIRMWARE_VERSION_NUM (FW_V_MAJOR*10000 + FW_V_MINOR*100 + FW_V_PATCH) // this is used in ID queries
 #define TERMINAL_GITHUB_REPO "https://github.com/MightyPork/esp-vt100-firmware"
 
-#endif //USER_MAIN_H_H
+#endif //ESP_VT100_FIRMWARE_VERSION_H