BIOS now attached to BOOTCPM command, fixed another screen editor bug

src/zvm_m65/z80_instr_load_8bit.s

@@ -277,18 +277,22 @@ Z80_instr_ED_5F:   ; LD A,R
 	ora REG_IFF2
 	sta REG_F
 
+	clc
 	lda REG_R06              ; register R only simulates random numbers
+	bpl @1
+	sec
+@1:
+	rol
 	eor VIC_RASTER
-	adc TIME+2
 	eor VIC_XPOS
 	sta REG_R06
 
 	and #%01111111
 	eor REG_R7               ; not 'ora', we want to reuse the 'garbage'
 	sta REG_A
-	bpl @1
+	bpl @2
 	+Z80_PUT_1_SF
-@1:
+@2:
 	+bne ZVM_next
 	+Z80_PUT_1_ZF
 	jmp ZVM_next

src/zvm_m65/zvm_bios.s

@@ -71,6 +71,9 @@ zvm_BIOS_00_BOOT:            ; Cold start
 	dew REG_AF               ; AF and SP have $FFFF value on start
 	dew REG_SP
 
+	lda TIME+2               ; give a little initial randomness to register R
+	sta REG_R06
+
 	; XXX load CPM3.SYS
 
 	; FALLTROUGH

src/zvm_m65/zvm_core.s

@@ -5,7 +5,47 @@
 
 ZVM_entry:
 
-	; XXX mark that this is the first start of CP/M iin the lifecycle, display BIOS information
+	; Reset stack pointer - this routine will never return
+
+	ldx #$FF
+	txs
+
+	; Skip the IRQ processing, even if Kernal reenables it
+
+	sei
+	lda #<return_from_interrupt
+	sta CINV+0 
+	lda #>return_from_interrupt
+	sta CINV+1
+
+	; Make sure $C000-$CFFF ROM is mapped-in, we keep our proxies there
+
+	lda VIC_CTRLA
+	ora #%00100000
+	sta VIC_CTRLA
+
+	; Setup colours, print welcome message
+
+	lda #$00
+	sta VIC_EXTCOL
+	sta VIC_BGCOL0
+
+	jsr PRIMM
+	!byte KEY_GREEN, KEY_ESC, 'o', KEY_CLR, KEY_C65_SHIFT_ON, KEY_TXT, KEY_C65_SHIFT_OFF
+	!pet "Open ROMs MEGA65 BIOS for CP/M", $0D
+	!pet "Zilog Z80 to 45GS02 translator", $0D
+	!byte $0D,$0D
+	!byte 0
+
+	; XXX code is not ready to progress further
+
+	jsr PRIMM
+	!byte $0D
+	!pet "* Implementation not finished yet - system HALTED *"
+	!byte 0
+@1
+	bra @1
+
 	jmp zvm_BIOS_00_BOOT
 
 ZVM_store_next:
@@ -71,28 +111,6 @@ Z80_instr_FD:      +ZVM_DISPATCH Z80_vectab_FD_0, Z80_vectab_FD_1              ;
 
 
 
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 ;
 ; Not implemented yet - XXX implement them!
 ;

src/zvm_m65/zvm_imports.s

@@ -0,0 +1,41 @@
+
+;; #IMPORT# KERNAL_0 = KERNAL_0_combined.sym
+;; #IMPORT# KERNAL_C = KERNAL_C_combined.sym
+
+;
+; Definitions for calling MEGA65 segment KERNAL_0 routines from ZVM_1
+;
+
+;; #ALIAS# CHROUT                          = KERNAL_C.proxy_Z1_CHROUT
+
+;; #ALIAS# return_from_interrupt           = KERNAL_0.return_from_interrupt
+
+
+; 'Print immediate', original implementation by Mike Barry, adapted to 65CE02, modified to preserve .Y
+; see http://www.6502.org/source/io/primm.htm
+
+PRIMM:
+
+	pla            ; get low part of (string address-1)
+	sta PTR1
+	pla            ; get high part of (string address-1)
+	sta PTR2
+	phy
+	+bra @2
+@1:
+	jsr CHROUT     ; output a string char
+@2:
+	inc PTR1       ; advance the string pointer
+	bne @3
+    inc PTR2
+@3:
+	ldy #$00
+	lda (PTR1), y  ; get string char
+	bne @1         ; output and continue if not NUL
+	ply
+	lda PTR2
+	pha
+	lda PTR1
+	pha
+
+	rts