Relocated monitor to top 16k

boot.asm

@@ -1,5 +1,7 @@
 STACK_TOP = 0xFFFF
 DELAY_LOOPS_PER_MS = 40
+MONITOR_BASE = 0xC000
+MONITOR_ROM_SOURCE = 0x0080
 
         .globl _main
         .globl _delay_ms
@@ -8,33 +10,49 @@ DELAY_LOOPS_PER_MS = 40
         .globl _enable_interrupts
         .globl _disable_interrupts
         .globl _jump_to
+        .globl monitor_image_end
         .globl s__DATA
         .globl l__DATA
         .globl s__INITIALIZER
         .globl s__INITIALIZED
         .globl l__INITIALIZER
 
-.area _ITABLE (ABS)
+.area _BOOT (ABS)
 
 .org 0x00
-        jp init
+        jp boot_copy
 .org 0x08
+boot_copy:
+        di
+        ld sp, #STACK_TOP
+        ld hl, #MONITOR_ROM_SOURCE
+        ld de, #MONITOR_BASE
+        ld bc, #(monitor_image_end - MONITOR_BASE)
+        ldir
+        jp init
+
+.area _ITABLE (ABS)
+
+; The executable vector page is part of the image copied to high RAM.
+.org MONITOR_BASE
+        jp init
+.org MONITOR_BASE + 0x08
         reti
-.org 0x10
+.org MONITOR_BASE + 0x10
         reti
-.org 0x18
+.org MONITOR_BASE + 0x18
         reti
-.org 0x20
+.org MONITOR_BASE + 0x20
         reti
-.org 0x28
+.org MONITOR_BASE + 0x28
         reti
-.org 0x30
+.org MONITOR_BASE + 0x30
         reti
-.org 0x38
+.org MONITOR_BASE + 0x38
         reti
 
-; ITABLE
-.org 0x40
+; IM 2 table: the CTC supplies vectors 40, 42, 44, and 46.
+.org MONITOR_BASE + 0x40
         .dw ctc_isr          ; CTC channel 0: vector 0x40
         .dw ctc_isr          ; CTC channel 1: vector 0x42
         .dw ctc_isr          ; CTC channel 2: vector 0x44
@@ -48,7 +66,7 @@ init:
         call gsinit
 
         ; Setup interrupt mode 2
-        xor a
+        ld a, #0xC0
         ld i, a
         im 2
         call _main
@@ -88,6 +106,7 @@ clear_loop:
 gsinit_done:
 .area _GSFINAL
         ret
+monitor_image_end:
 
 .area _CODE