- Fixed BRK flags (clear D, set I, N/Z set from wrong EXX set)
- Added Applesoft BASIC [Lite] and Lee Davidson's Enhanced BASIC - First byte of emulator at &9000 appears to be ROM (for Applesoft BASIC) - Terminal output now supports lower-case characters (for Enhanced BASIC) - Updated Ken Wessen's BASIC+Krusader assembler to v1.3
This commit is contained in:
Simon Owen
parent
64db2eff61
commit
c571f7dd59
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@ -1,6 +1,6 @@
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; Apple 1 emulator for SAM Coupe, by Simon Owen
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;
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; Version 1.1 (27/8/2008)
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; Version 1.2 (5/9/2008)
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;
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; WWW: http://simonowen.com/sam/apple1emu/
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@ -21,8 +21,6 @@ low_page: equ 3 ; LMPR during emulation
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screen_page: equ 5 ; SAM display
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file_page: equ 6 ; File import text page
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bord_invalid: equ 2 ; Invalid instruction (red)
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m6502_nmi: equ &fffa ; nmi vector address
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m6502_reset: equ &fffc ; reset vector address
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m6502_int: equ &fffe ; int vector address (also for BRK)
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@ -139,19 +137,16 @@ back_chr: ld a,l
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jr no_wrap
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; Map display character from SAM to Apple 1
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map_chr: cp &20
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jr c,invalid_chr
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and %10111111
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xor %01100000
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ret
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invalid_chr: xor a
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map_chr: sub &20
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ret nc
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xor a
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ret
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; Display character in A at current cursor position
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display_chr: add a,a ; * 2
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add a,a ; * 4
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ld l,a
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ld h,0
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add hl,hl ; * 4
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add hl,hl ; * 8
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ld de,font_data
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add hl,de
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@ -359,7 +354,7 @@ no_key:
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call display_chr ; show it
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pop af
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done_draw2: call advance_chr ; advance the cursor position
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ld a,&3f ; cursor block
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ld a,&5f ; cursor block
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call display_chr ; show cursor
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done_draw:
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no_char:
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@ -442,16 +437,13 @@ execute: ld a,&1a ; LD A,(DE)
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i_undoc_3: inc de ; 3-byte NOP
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i_undoc_2: inc de ; 2-byte NOP
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i_undoc_1:
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; ld a,bord_invalid
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; out (border),a
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jp (ix)
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i_undoc_1: jp (ix) ; NOP
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read_write_loop:
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write_loop: ld a,h
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cp &d0 ; I/O area?
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jr z,write_trap
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cp base/256 ; emulator or ROMs above?
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jr nc,write_trap
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zwrite_loop:
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main_loop: ld a,(de) ; 7/7/15 - fetch opcode
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@ -462,13 +454,19 @@ main_loop: ld a,(de) ; 7/7/15 - fetch opcode
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jp (hl) ; 4/5/9 - execute!
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; = 35T (official) / 40T (off-screen) / 72T (on-screen)
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write_trap: ld a,l
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write_trap: cp &d0
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jr nz,write_rom
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ld a,l
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cp &12 ; display char?
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jr z,chr_write
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jp (ix)
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chr_write: set 7,(hl) ; display busy
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jp (ix)
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write_rom: ld a,&f3 ; Z80 DI opcode
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ld (base),a ; emulator appears to be in ROM for RAM tests
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jp (ix)
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read_loop: ld a,h
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cp &d0
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jr z,read_trap
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@ -598,8 +596,9 @@ msb_table: defb op_00>>8, op_01>>8, op_02>>8, op_03>>8, op_04>>8, op_05>>8,
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defs -$\256 ; align to 256-byte boundary
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; !"#$%&1()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]`abcdefghijklmnopqrstuvwxyz{|}~
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font_data:
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MDAT "font.bin"
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MDAT "font.bin"
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mask_data: defb %00000011,%11111111
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defb %11000000,%11111111
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@ -613,18 +612,47 @@ length: equ end-start
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Instruction implementations
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INC "opimpl.inc"
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; Instruction implementations
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INC "opimpl.inc"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Woz Monitor ROM (&ff00-&ffff)
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; May be overwritten by includes below
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dump &ff00
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MDAT "apple1.rom"
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; Ken Wessen's custom BASIC+Krusader+Monitor ROM (&e000-&ffff)
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; BRK handler points to mini-monitor in this version
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; Use RAM-based Applesoft BASIC by default
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IF 1
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; Applesoft BASIC [Lite] (6000-7FFF)
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; http://cowgod.org/replica1/applesoft/
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dump low_page,&6000
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MDAT "applesoft-lite-0.4-ram.bin"
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ELSE
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; Lee Davidson's Enhanced BASIC (5800-77CE)
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; http://members.lycos.co.uk/leeedavison/6502/ehbasic/
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dump low_page,&5800
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MDAT "ehbasic.bin"
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ENDIF
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; Use Ken Wessen's BASIC+assembler by default
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IF 1
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; Ken Wessen's custom BASIC + Krusader assembler + enhanced monitor (E000-FFFF)
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; BRK handler points to mini-monitor in this version
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; http://school.anhb.uwa.edu.au/personalpages/kwessen/apple1/Krusader.htm
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dump &e000
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MDAT "65C02.rom.bin"
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MDAT "65C02.rom.bin"
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ELSE
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; Applesoft BASIC [Lite] + Woz monitor (E000-FFFF)
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; http://cowgod.org/replica1/applesoft/
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dump &e000
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MDAT "applesoft-lite-0.4.bin"
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ENDIF
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; Original Monitor ROM (&ff00-&ffff)
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; If uncommented, this will replace the monitor ROM section from above
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dump &ff00
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MDAT "apple1.rom"
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; Test program to output the character set (5000-500B)
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; LDX $00 ; loop: TXA ; JSR echo ; INX ; BRA loop
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dump low_page,&5000
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defb &a2, &00, &8a, &20, &ef, &ff, &e8, &80, &f9
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@ -1,6 +1,6 @@
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; Opcode table positions (auto-generated by opdefs.pl)
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op_00: equ &b000 ; +38
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op_00: equ &b000 ; +42
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op_01: equ &b401 ; +18
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op_02: equ &ba02 ; +3
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op_03: equ &b103 ; +3
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14
opdefs.pl
14
opdefs.pl
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@ -2,12 +2,15 @@
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#
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# Calculates opcode addresses for the inline instruction decoding table
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#
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# Used by the VIC-20 emulator, available from:
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# Used by the Apple 1 emulator, available from:
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#
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# http://simonowen.com/sam/apple1emu/
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$source = 'apple1emu.asm';
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$codeend = 0xc000;
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# Assemble, outputting the symbols containing opcode implementation lengths
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$_ = `pyz80.py -s op_.*_len apple1emu.asm`;
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$_ = `pyz80.py -s op_.*_len $source`;
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# Create include file for definitions
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my $outfile = 'opdefs.inc';
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@ -19,9 +22,10 @@ if ($?)
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{
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# Create dummy offset list to allow lengths to be calculated
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for (0..255) {
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printf FILE "op_%02x: equ &b000\n", $_;
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printf FILE "op_%02x: equ &%04x\n", $_, $codeend-0x1000;
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}
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print "Assembly error, creating dummy definitions!\n";
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exit;
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}
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@ -68,8 +72,8 @@ MSB:
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}
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}
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# Position base so code finishes just before &c000
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$base = 0xc000 - (($size + 0xff) & ~0xff);
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# Position base so code finishes at the required point
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$base = $codeend - (($size + 0xff) & ~0xff);
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print "Size = $size, used = $used, slack = ", $size-$used, "\n";
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29
opimpl.inc
29
opimpl.inc
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@ -1,10 +1,20 @@
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; 65C02 instruction implementations
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;
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; NOTE: If you change this file, opdefs.inc must be rebuilt by running
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; opdefs.pl (requires the pyz80 assembler)
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INC "opdefs.inc"
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org op_00
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dump $
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i_brk: inc de ; return to BRK+2
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ex af,af' ; get C
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inc c
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dec c ; set N Z
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push af ; save flags for below
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ex af,af' ; save C
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ld a,d ; PCH
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exx
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ld (hl),a ; push return PCH
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@ -14,22 +24,21 @@ i_brk: inc de ; return to BRK+2
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exx
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ld (hl),a ; push return PCL
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dec l ; S--
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ex af,af' ; carry
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inc c
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dec c ; set N Z
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push af ; save flags
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ex af,af' ; save carry
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pop bc
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pop bc ; Z80 flags in C
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ld a,c
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and %10000001 ; keep N and C
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bit 6,c ; check Z
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and %10000001 ; keep Z80 N and C
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bit 6,c ; check Z80 Z
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jr z,brk_nz
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or %00000010 ; set Z
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brk_nz: or e ; merge V
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or d ; merge T D I
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or %00010000 ; set B
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or d ; merge T B D I
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or %00010000 ; set B (stack value only)
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ld (hl),a ; push P
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dec l ; S--
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res 3,d ; clear D [65C02]
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set 2,d ; set I (disable interrupts)
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exx
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ld de,(m6502_int) ; fetch interrupt handler
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jp (ix) ; main_loop
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