diff --git a/framework/settings.c b/framework/settings.c
index 2673dae..c1b6213 100644
--- a/framework/settings.c
+++ b/framework/settings.c
@@ -300,7 +300,6 @@ void settings_load_ini_begin(void)
     SystemSettings.loading_inifile = 0;
 }
 
-
 void settings_load_ini_key(const char *restrict section, const char *restrict key, const char *restrict value)
 {
 //    dbg("[%s] %s = %s", section, key, value);
@@ -312,6 +311,7 @@ void settings_load_ini_key(const char *restrict section, const char *restrict ke
     if (streq(section, "SYSTEM")) {
         if (SystemSettings.loading_inifile == 0) {
             SystemSettings.loading_inifile = 'S';
+            systemsettings_mco_teardown();
             systemsettings_loadDefaults();
         }
 
@@ -356,4 +356,8 @@ void settings_load_ini_end(void)
         bool suc = ureg_finalize_all_init();
         if (!suc) dbg("Some units failed to init!!");
     }
+
+    if (SystemSettings.loading_inifile == 'S') {
+        systemsettings_mco_init();
+    }
 }
diff --git a/framework/system_settings.c b/framework/system_settings.c
index 73f8ae7..ec8c780 100644
--- a/framework/system_settings.c
+++ b/framework/system_settings.c
@@ -7,6 +7,8 @@
 #include "utils/str_utils.h"
 #include "platform/lock_jumper.h"
 #include "cfg_utils.h"
+#include "resources.h"
+#include "unit_base.h"
 
 struct system_settings SystemSettings;
 
@@ -15,6 +17,8 @@ void systemsettings_loadDefaults(void)
 {
     SystemSettings.visible_vcom = true;
     SystemSettings.ini_comments = true;
+    SystemSettings.enable_mco = false;
+    SystemSettings.mco_prediv = 7;
 }
 
 /** Load defaults and init flags */
@@ -31,18 +35,45 @@ void systemsettings_init(void)
 void systemsettings_save(PayloadBuilder *pb)
 {
     pb_char(pb, 'S');
-    pb_u8(pb, 0); // settings format version
+    pb_u8(pb, 1); // settings format version
 
     { // system settings
         pb_bool(pb, SystemSettings.visible_vcom);
         pb_bool(pb, SystemSettings.ini_comments);
+
+        pb_bool(pb, SystemSettings.enable_mco);
+        pb_u8(pb, SystemSettings.mco_prediv);
     } // end system settings
 }
 
+void systemsettings_mco_teardown(void)
+{
+    if (SystemSettings.enable_mco) {
+        rsc_free(&UNIT_SYSTEM, R_PA8);
+        LL_RCC_ConfigMCO(LL_RCC_MCO1SOURCE_NOCLOCK, 0);
+    }
+}
+
+void systemsettings_mco_init(void)
+{
+    if (SystemSettings.enable_mco) {
+        assert_param(rsc_claim(&UNIT_SYSTEM, R_PA8) == E_SUCCESS);
+
+        assert_param(E_SUCCESS == hw_configure_gpiorsc_af(R_PA8, LL_GPIO_AF_0));
+        LL_RCC_ConfigMCO(LL_RCC_MCO1SOURCE_SYSCLK,
+                         SystemSettings.mco_prediv << RCC_CFGR_MCOPRE_Pos);
+    } else {
+        LL_RCC_ConfigMCO(LL_RCC_MCO1SOURCE_NOCLOCK, 0);
+    }
+}
+
 // from binary
 bool systemsettings_load(PayloadParser *pp)
 {
     if (pp_char(pp) != 'S') return false;
+
+    systemsettings_mco_teardown();
+
     uint8_t version = pp_u8(pp);
 
     { // system settings
@@ -50,9 +81,14 @@ bool systemsettings_load(PayloadParser *pp)
         SystemSettings.ini_comments = pp_bool(pp);
 
         // conditional fields based on version
-        (void) version;
+        if (version >= 1) {
+            SystemSettings.enable_mco = pp_bool(pp);
+            SystemSettings.mco_prediv = pp_u8(pp);
+        }
     } // end system settings
 
+    systemsettings_mco_init();
+
     return pp->ok;
 }
 
@@ -65,10 +101,16 @@ void systemsettings_build_ini(IniWriter *iw)
     iw_section(iw, "SYSTEM");
 
     iw_comment(iw, "Data link accessible as virtual comport (Y, N)");
-    iw_entry(iw, "expose_vcom", str_yn(SystemSettings.visible_vcom));
+    iw_entry_s(iw, "expose-vcom", str_yn(SystemSettings.visible_vcom));
 
     iw_comment(iw, "Show comments in INI files (Y, N)");
-    iw_entry(iw, "ini_comments", str_yn(SystemSettings.ini_comments));
+    iw_entry_s(iw, "ini-comments", str_yn(SystemSettings.ini_comments));
+
+    iw_cmt_newline(iw);
+    iw_comment(iw, "Output core clock on PA8 (Y, N)");
+    iw_entry_s(iw, "mco-enable", str_yn(SystemSettings.enable_mco));
+    iw_comment(iw, "Output clock prediv (1,2,...,128)");
+    iw_entry_d(iw, "mco-prediv", (1<<SystemSettings.mco_prediv));
 }
 
 /**
@@ -77,15 +119,37 @@ void systemsettings_build_ini(IniWriter *iw)
 bool systemsettings_load_ini(const char *restrict key, const char *restrict value)
 {
     bool suc = true;
-    if (streq(key, "expose_vcom")) {
+    if (streq(key, "expose-vcom")) {
         bool yn = cfg_bool_parse(value, &suc);
         if (suc) SystemSettings.visible_vcom = yn;
     }
 
-    if (streq(key, "ini_comments")) {
+    if (streq(key, "ini-comments")) {
         bool yn = cfg_bool_parse(value, &suc);
         if (suc) SystemSettings.ini_comments = yn;
     }
 
+    if (streq(key, "mco-enable")) {
+        bool yn = cfg_bool_parse(value, &suc);
+        if (suc) SystemSettings.enable_mco = yn;
+    }
+
+    if (streq(key, "mco-prediv")) {
+        int val = cfg_u8_parse(value, &suc);
+        if (suc) {
+            switch (val) {
+                case 1: SystemSettings.mco_prediv = 0; break;
+                case 2: SystemSettings.mco_prediv = 1; break;
+                case 4: SystemSettings.mco_prediv = 2; break;
+                case 8: SystemSettings.mco_prediv = 3; break;
+                case 16: SystemSettings.mco_prediv = 4; break;
+                case 32: SystemSettings.mco_prediv = 5; break;
+                case 64: SystemSettings.mco_prediv = 6; break;
+                default:
+                case 128: SystemSettings.mco_prediv = 7; break;
+            }
+        }
+    }
+
     return suc;
 }
diff --git a/framework/system_settings.h b/framework/system_settings.h
index b4b2c65..b9678c3 100644
--- a/framework/system_settings.h
+++ b/framework/system_settings.h
@@ -18,6 +18,8 @@
 struct system_settings {
     bool visible_vcom;
     bool ini_comments;
+    bool enable_mco;
+    uint8_t mco_prediv;
 
     // Support flags put here for scoping, but not atcually part of the persistent settings
     volatile bool editable; //!< True if we booted with the LOCK jumper removed
@@ -60,4 +62,7 @@ void systemsettings_build_ini(IniWriter *iw);
  */
 bool systemsettings_load_ini(const char *restrict key, const char *restrict value);
 
+void systemsettings_mco_teardown(void);
+void systemsettings_mco_init(void);
+
 #endif //GEX_SYSTEM_SETTINGS_H