diff --git a/src/cpu/callback.cpp b/src/cpu/callback.cpp
index e5294bf03..18de12b6f 100644
--- a/src/cpu/callback.cpp
+++ b/src/cpu/callback.cpp
@@ -403,32 +403,24 @@ Bitu CALLBACK_SetupExtra(Bitu callback, Bitu type, PhysPt physAddress, bool use_
 		phys_writeb(physAddress+0x0e,(uint8_t)0xcf);		//An IRET Instruction
 		return (use_cb?0x13:0x0f);
 	case CB_IRQ1:	// keyboard int9
-		phys_writeb(physAddress+0x00,(uint8_t)0x50);			// push ax
 		if (machine == MCH_PCJR) {
 			/*      IBM PCjr reads the infrared input on NMI interrupt, which then calls INT 48h to
 			 *      translate to IBM PC/XT scan codes before passing AL directly to IRQ1 (INT 9).
 			 *      PCjr keyboard handlers, including games made for the PCjr, assume the scan code
-			 *      is in AL and do not read the I/O port.
-			 *
-			 *      PCjr has an XT style keyboard interface where it is necessary to set, then clear,
-			 *      bit 7 of port 61h to re-enable the keyboard.
-			 *
-			 *      Because we're talking to our own emulation, it is sufficient to just clear bit 7.*/
-			phys_writew(physAddress+0x01,(uint16_t)0x60E4);		// in al, 0x60
-
+			 *      is in AL and do not read the I/O port. */
 			if (use_cb) {
-				phys_writeb(physAddress+0x03,(uint8_t)0xFE);		//GRP 4
-				phys_writeb(physAddress+0x04,(uint8_t)0x38);		//Extra Callback instruction
-				phys_writew(physAddress+0x05,(uint16_t)callback);	//The immediate word
+				phys_writeb(physAddress+0x00,(uint8_t)0xFE);		//GRP 4
+				phys_writeb(physAddress+0x01,(uint8_t)0x38);		//Extra Callback instruction
+				phys_writew(physAddress+0x02,(uint16_t)callback);	//The immediate word
 				physAddress+=4;
 			}
 
 			/* It wasn't an interrupt, so there's no need to ack */
-			phys_writeb(physAddress+0x03,(uint8_t)0x58);			// pop ax
-			phys_writeb(physAddress+0x04,(uint8_t)0xcf);			//An IRET Instruction
-			return (use_cb?0x09:0x05);
+			phys_writeb(physAddress+0x00,(uint8_t)0xcf);			//An IRET Instruction
+			return (use_cb?0x05:0x01);
 		}
 		else {
+			phys_writeb(physAddress+0x00,(uint8_t)0x50);			// push ax
 			if (IS_PC98_ARCH) {
 				/* NTS: NEC PC-98 does not have keyboard input on port 60h, it's a 8251 UART elsewhere. */
 				phys_writew(physAddress+0x01,(uint16_t)0x9090);		// nop, nop
diff --git a/src/ints/bios_keyboard.cpp b/src/ints/bios_keyboard.cpp
index d959acf88..6853c96d8 100644
--- a/src/ints/bios_keyboard.cpp
+++ b/src/ints/bios_keyboard.cpp
@@ -1180,19 +1180,45 @@ static Bitu PCjr_NMI_Keyboard_Handler(void) {
  * Fn + 1 into the scan code for F1. */
 static Bitu PCjr_INT48_Keyboard_Handler(void) {
     uint8_t pcjr_f = mem_readb(BIOS_KEYBOARD_PCJR_FLAG2);
+    uint8_t flags1 = mem_readb(BIOS_KEYBOARD_FLAGS1);
 
-    switch (reg_al&0x7F) {
-        case 0x54: /* Fn key */
-            if (reg_al&0x80/*release*/) pcjr_f &= ~BIOS_KEYBOARD_PCJR_FLAG2_FN_FLAG;
-            else pcjr_f |= BIOS_KEYBOARD_PCJR_FLAG2_FN_FLAG;
-            goto skip_int9;
-        default: /* AL without translation */
-            break;
+    if ((reg_al&0x7F) == 0x54) {
+        if (reg_al&0x80/*release*/) pcjr_f &= ~BIOS_KEYBOARD_PCJR_FLAG2_FN_FLAG;
+        else pcjr_f |= BIOS_KEYBOARD_PCJR_FLAG2_FN_FLAG;
+        goto skip_int9;
     }
 
+#define UPDATESHIFT(x) if (x) { flags1 &= ~0x3; /*break*/ } else { flags1 |= 0x3; /*make*/ }
+#define CLEARSHIFT() UPDATESHIFT(1/*break*/)
+
+    if (pcjr_f & (BIOS_KEYBOARD_PCJR_FLAG2_FN_FLAG|BIOS_KEYBOARD_PCJR_FLAG2_FN_LOCK)) {
+        const uint8_t bc = reg_al & 0x80;
+        switch (reg_al&0x7F) {
+            case 0x02: reg_al=0x3B|bc; break;/*Fn+1 = F1*/
+            case 0x03: reg_al=0x3C|bc; break;/*Fn+2 = F2*/
+            case 0x04: reg_al=0x3D|bc; break;/*Fn+3 = F3*/
+            case 0x05: reg_al=0x3E|bc; break;/*Fn+4 = F4*/
+            case 0x06: reg_al=0x3F|bc; break;/*Fn+5 = F5*/
+            case 0x07: reg_al=0x40|bc; break;/*Fn+6 = F6*/
+            case 0x08: reg_al=0x41|bc; break;/*Fn+7 = F7*/
+            case 0x09: reg_al=0x42|bc; break;/*Fn+8 = F8*/
+            case 0x0A: reg_al=0x43|bc; break;/*Fn+9 = F9*/
+            case 0x0B: reg_al=0x44|bc; break;/*Fn+10 = F10*/
+            case 0x1A: reg_al=0x2B|bc; UPDATESHIFT(bc); break;/*Fn+[ = | which is SHIFT+\ */
+            case 0x1B: reg_al=0x29|bc; UPDATESHIFT(bc); break;/*Fn+] = ~ which is SHIFT+` */
+            case 0x28: reg_al=0x29|bc; CLEARSHIFT(); break;/*Fn+' = ` which is unshifted ` */
+            case 0x35: reg_al=0x2B|bc; CLEARSHIFT(); break;/*Fn+/ = \\ which is unshifted \\ */
+            default: break;
+        }
+    }
+
+#undef UPDATESHIFT
+#undef CLEARSHIFT
+
     reg_eip++; /* skip over IRET */
 skip_int9: /* if we do not skip IRET, then INT 48h returns without calling INT 9h */
 
+    mem_writeb(BIOS_KEYBOARD_FLAGS1,flags1);
     mem_writeb(BIOS_KEYBOARD_PCJR_FLAG2,pcjr_f);
     return CBRET_NONE;
 }