mirror of
https://github.com/tebl/RC6502-Apple-1-Replica.git
synced 2024-11-28 07:49:25 +00:00
253 lines
18 KiB
Plaintext
253 lines
18 KiB
Plaintext
|
0000- 4 ;-------------------------------------------------------------------------
|
||
|
|
0000- 5 ;
|
||
|
|
0000- 6 ; The WOZ Monitor for the Apple 1
|
||
|
|
0000- 7 ; Written by Steve Wozniak 1976
|
||
|
|
0000- 8 ;
|
||
|
|
0000- 9 ;-------------------------------------------------------------------------
|
||
|
|
0000- 10
|
||
|
|
0000- 11
|
||
|
|
0000- 12 ;-------------------------------------------------------------------------
|
||
|
|
0000- 13 ; Memory declaration
|
||
|
|
0000- 14 ;-------------------------------------------------------------------------
|
||
|
|
0000- 15
|
||
|
|
0024- 16 XAML .EQ $24 Last "opened" location Low
|
||
|
|
0025- 17 XAMH .EQ $25 Last "opened" location High
|
||
|
|
0026- 18 STL .EQ $26 Store address Low
|
||
|
|
0027- 19 STH .EQ $27 Store address High
|
||
|
|
0028- 20 L .EQ $28 Hex value parsing Low
|
||
|
|
0029- 21 H .EQ $29 Hex value parsing High
|
||
|
|
002A- 22 YSAV .EQ $2A Used to see if hex value is given
|
||
|
|
002B- 23 MODE .EQ $2B $00=XAM, $7F=STOR, $AE=BLOCK XAM
|
||
|
|
0000- 24
|
||
|
|
0200- 25 IN .EQ $0200,$027F Input buffer
|
||
|
|
0000- 26
|
||
|
|
D010- 27 KBD .EQ $D010 PIA.A keyboard input
|
||
|
|
D011- 28 KBDCR .EQ $D011 PIA.A keyboard control register
|
||
|
|
D012- 29 DSP .EQ $D012 PIA.B display output register
|
||
|
|
D013- 30 DSPCR .EQ $D013 PIA.B display control register
|
||
|
|
0000- 31
|
||
|
|
0000- 32 ; KBD b7..b0 are inputs, b6..b0 is ASCII input, b7 is constant high
|
||
|
|
0000- 33 ; Programmed to respond to low to high KBD strobe
|
||
|
|
0000- 34 ; DSP b6..b0 are outputs, b7 is input
|
||
|
|
0000- 35 ; CB2 goes low when data is written, returns high when CB1 goes high
|
||
|
|
0000- 36 ; Interrupts are enabled, though not used. KBD can be jumpered to IRQ,
|
||
|
|
0000- 37 ; whereas DSP can be jumpered to NMI.
|
||
|
|
0000- 38
|
||
|
|
0000- 39 ;-------------------------------------------------------------------------
|
||
|
|
0000- 40 ; Constants
|
||
|
|
0000- 41 ;-------------------------------------------------------------------------
|
||
|
|
0000- 42
|
||
|
|
00DF- 43 BS .EQ $DF Backspace key, arrow left key
|
||
|
|
008D- 44 CR .EQ $8D Carriage Return
|
||
|
|
009B- 45 ESC .EQ $9B ESC key
|
||
|
|
00DC- 46 PROMPT .EQ "\" Prompt character
|
||
|
|
0000- 47
|
||
|
|
0000- 48 ;-------------------------------------------------------------------------
|
||
|
|
0000- 49 ; Let's get started
|
||
|
|
0000- 50 ;
|
||
|
|
0000- 51 ; Remark the RESET routine is only to be entered by asserting the RESET
|
||
|
|
0000- 52 ; line of the system. This ensures that the data direction registers
|
||
|
|
0000- 53 ; are selected.
|
||
|
|
0000- 54 ;-------------------------------------------------------------------------
|
||
|
|
FF00- 55 .OR $FF00
|
||
|
|
FF00-D8 56 ( 2) RESET CLD Clear decimal arithmetic mode
|
||
|
|
FF01-58 57 ( 2) CLI
|
||
|
|
FF02-A0 7F 58 ( 2) LDY #%0111.1111 Mask for DSP data direction reg
|
||
|
|
FF04-8C 12 D0 59 ( 4) STY DSP (DDR mode is assumed after reset)
|
||
|
|
FF07-A9 A7 60 ( 2) LDA #%1010.0111 KBD and DSP control register mask
|
||
|
|
FF09-8D 11 D0 61 ( 4) STA KBDCR Enable interrupts, set CA1, CB1 for
|
||
|
|
FF0C-8D 13 D0 62 ( 4) STA DSPCR positive edge sense/output mode.
|
||
|
|
FF0F- 63
|
||
|
|
FF0F- 64 ; Program falls through to the GETLINE routine to save some program bytes
|
||
|
|
FF0F- 65 ; Please note that Y still holds $7F, which will cause an automatic Escape
|
||
|
|
FF0F- 66
|
||
|
|
FF0F- 67 ;-------------------------------------------------------------------------
|
||
|
|
FF0F- 68 ; The GETLINE process
|
||
|
|
FF0F- 69 ;-------------------------------------------------------------------------
|
||
|
|
FF0F- 70
|
||
|
|
FF0F-C9 DF 71 ( 2) NOTCR CMP #BS Backspace key?
|
||
|
|
FF11-F0 13 72 (2**) BEQ BACKSPACE Yes
|
||
|
|
FF13-C9 9B 73 ( 2) CMP #ESC ESC?
|
||
|
|
FF15-F0 03 74 (2**) BEQ ESCAPE Yes
|
||
|
|
FF17-C8 75 ( 2) INY Advance text index
|
||
|
|
FF18-10 0F 76 (2**) BPL NEXTCHAR Auto ESC if line longer than 127
|
||
|
|
FF1A- 77
|
||
|
|
FF1A-A9 DC 78 ( 2) ESCAPE LDA #PROMPT Print prompt character
|
||
|
|
FF1C-20 EF FF 79 ( 6) JSR ECHO Output it.
|
||
|
|
FF1F- 80
|
||
|
|
FF1F-A9 8D 81 ( 2) GETLINE LDA #CR Send CR
|
||
|
|
FF21-20 EF FF 82 ( 6) JSR ECHO
|
||
|
|
FF24- 83
|
||
|
|
FF24-A0 01 84 ( 2) LDY #0+1 Start a new input line
|
||
|
|
FF26-88 85 ( 2) BACKSPACE DEY Backup text index
|
||
|
|
FF27-30 F6 86 (2**) BMI GETLINE Oops, line's empty, reinitialize
|
||
|
|
FF29- 87
|
||
|
|
FF29-AD 11 D0 88 ( 4) NEXTCHAR LDA KBDCR Wait for key press
|
||
|
|
FF2C-10 FB 89 (2**) BPL NEXTCHAR No key yet!
|
||
|
|
FF2E-AD 10 D0 90 ( 4) LDA KBD Load character. B7 should be '1'
|
||
|
|
FF31-99 00 02 91 ( 5) STA IN,Y Add to text buffer
|
||
|
|
FF34-20 EF FF 92 ( 6) JSR ECHO Display character
|
||
|
|
FF37-C9 8D 93 ( 2) CMP #CR
|
||
|
|
FF39-D0 D4 94 (2**) BNE NOTCR It's not CR!
|
||
|
|
FF3B- 95
|
||
|
|
FF3B- 96 ; Line received, now let's parse it
|
||
|
|
FF3B- 97
|
||
|
|
FF3B-A0 FF 98 ( 2) LDY #-1 Reset text index
|
||
|
|
FF3D-A9 00 99 ( 2) LDA #0 Default mode is XAM
|
||
|
|
FF3F-AA 100 ( 2) TAX X=0
|
||
|
|
FF40- 101
|
||
|
|
FF40-0A 102 ( 2) SETSTOR ASL Leaves $7B if setting STOR mode
|
||
|
|
FF41- 103
|
||
|
|
FF41-85 2B 104 ( 2) SETMODE STA MODE Set mode flags
|
||
|
|
FF43- 105
|
||
|
|
FF43-C8 106 ( 2) BLSKIP INY Advance text index
|
||
|
|
FF44- 107
|
||
|
|
FF44-B9 00 02 108 ( 4*) NEXTITEM LDA IN,Y Get character
|
||
|
|
FF47-C9 8D 109 ( 2) CMP #CR
|
||
|
|
FF49-F0 D4 110 (2**) BEQ GETLINE We're done if it's CR!
|
||
|
|
FF4B-C9 AE 111 ( 2) CMP #"."
|
||
|
|
FF4D-90 F4 112 (2**) BCC BLSKIP Ignore everything below "."!
|
||
|
|
FF4F-F0 F0 113 (2**) BEQ SETMODE Set BLOCK XAM mode ("." = $AE)
|
||
|
|
FF51-C9 BA 114 ( 2) CMP #":"
|
||
|
|
FF53-F0 EB 115 (2**) BEQ SETSTOR Set STOR mode! $BA will become $7B
|
||
|
|
FF55-C9 D2 116 ( 2) CMP #"R"
|
||
|
|
FF57-F0 3B 117 (2**) BEQ RUN Run the program! Forget the rest
|
||
|
|
FF59-86 28 118 ( 3) STX L Clear input value (X=0)
|
||
|
|
FF5B-86 29 119 ( 3) STX H
|
||
|
|
FF5D-84 2A 120 ( 3) STY YSAV Save Y for comparison
|
||
|
|
FF5F- 121
|
||
|
|
FF5F- 122 ; Here we're trying to parse a new hex value
|
||
|
|
FF5F- 123
|
||
|
|
FF5F-B9 00 02 124 ( 4*) NEXTHEX LDA IN,Y Get character for hex test
|
||
|
|
FF62-49 B0 125 ( 2) EOR #$B0 Map digits to 0-9
|
||
|
|
FF64-C9 0A 126 ( 2) CMP #9+1 Is it a decimal digit?
|
||
|
|
FF66-90 06 127 (2**) BCC DIG Yes!
|
||
|
|
FF68-69 88 128 ( 2) ADC #$88 Map letter "A"-"F" to $FA-FF
|
||
|
|
FF6A-C9 FA 129 ( 2) CMP #$FA Hex letter?
|
||
|
|
FF6C-90 11 130 (2**) BCC NOTHEX No! Character not hex
|
||
|
|
FF6E- 131
|
||
|
|
FF6E-0A 132 ( 2) DIG ASL
|
||
|
|
FF6F-0A 133 ( 2) ASL Hex digit to MSD of A
|
||
|
|
FF70-0A 134 ( 2) ASL
|
||
|
|
FF71-0A 135 ( 2) ASL
|
||
|
|
FF72- 136
|
||
|
|
FF72-A2 04 137 ( 2) LDX #4 Shift count
|
||
|
|
FF74-0A 138 ( 2) HEXSHIFT ASL Hex digit left, MSB to carry
|
||
|
|
FF75-26 28 139 ( 5) ROL L Rotate into LSD
|
||
|
|
FF77-26 29 140 ( 5) ROL H Rotate into MSD's
|
||
|
|
FF79-CA 141 ( 2) DEX Done 4 shifts?
|
||
|
|
FF7A-D0 F8 142 (2**) BNE HEXSHIFT No, loop
|
||
|
|
FF7C-C8 143 ( 2) INY Advance text index
|
||
|
|
FF7D-D0 E0 144 (2**) BNE NEXTHEX Always taken
|
||
|
|
FF7F- 145
|
||
|
|
FF7F-C4 2A 146 ( 3) NOTHEX CPY YSAV Was at least 1 hex digit given?
|
||
|
|
FF81-F0 97 147 (2**) BEQ ESCAPE No! Ignore all, start from scratch
|
||
|
|
FF83- 148
|
||
|
|
FF83-24 2B 149 ( 3) BIT MODE Test MODE byte
|
||
|
|
FF85-50 10 150 (2**) BVC NOTSTOR B6=0 is STOR, 1 is XAM or BLOCK XAM
|
||
|
|
FF87- 151
|
||
|
|
FF87- 152 ; STOR mode, save LSD of new hex byte
|
||
|
|
FF87- 153
|
||
|
|
FF87-A5 28 154 ( 3) LDA L LSD's of hex data
|
||
|
|
FF89-81 26 155 ( 6) STA (STL,X) Store current 'store index'(X=0)
|
||
|
|
FF8B-E6 26 156 ( 5) INC STL Increment store index.
|
||
|
|
FF8D-D0 B5 157 (2**) BNE NEXTITEM No carry!
|
||
|
|
FF8F-E6 27 158 ( 5) INC STH Add carry to 'store index' high
|
||
|
|
FF91-4C 44 FF 159 ( 3) TONEXTITEM JMP NEXTITEM Get next command item.
|
||
|
|
FF94- 160
|
||
|
|
FF94- 161 ;-------------------------------------------------------------------------
|
||
|
|
FF94- 162 ; RUN user's program from last opened location
|
||
|
|
FF94- 163 ;-------------------------------------------------------------------------
|
||
|
|
FF94- 164
|
||
|
|
FF94-6C 24 00 165 ( 5) RUN JMP (XAML) Run user's program
|
||
|
|
FF97- 166
|
||
|
|
FF97- 167 ;-------------------------------------------------------------------------
|
||
|
|
FF97- 168 ; We're not in Store mode
|
||
|
|
FF97- 169 ;-------------------------------------------------------------------------
|
||
|
|
FF97- 170
|
||
|
|
FF97-30 2B 171 (2**) NOTSTOR BMI XAMNEXT B7 = 0 for XAM, 1 for BLOCK XAM
|
||
|
|
FF99- 172
|
||
|
|
FF99- 173 ; We're in XAM mode now
|
||
|
|
FF99- 174
|
||
|
|
FF99-A2 02 175 ( 2) LDX #2 Copy 2 bytes
|
||
|
|
FF9B-B5 27 176 ( 4) SETADR LDA L-1,X Copy hex data to
|
||
|
|
FF9D-95 25 177 ( 4) STA STL-1,X 'store index'
|
||
|
|
FF9F-95 23 178 ( 4) STA XAML-1,X and to 'XAM index'
|
||
|
|
FFA1-CA 179 ( 2) DEX Next of 2 bytes
|
||
|
|
FFA2-D0 F7 180 (2**) BNE SETADR Loop unless X = 0
|
||
|
|
FFA4- 181
|
||
|
|
FFA4- 182 ; Print address and data from this address, fall through next BNE.
|
||
|
|
FFA4- 183
|
||
|
|
FFA4-D0 14 184 (2**) NXTPRNT BNE PRDATA NE means no address to print
|
||
|
|
FFA6-A9 8D 185 ( 2) LDA #CR Print CR first
|
||
|
|
FFA8-20 EF FF 186 ( 6) JSR ECHO
|
||
|
|
FFAB-A5 25 187 ( 3) LDA XAMH Output high-order byte of address
|
||
|
|
FFAD-20 DC FF 188 ( 6) JSR PRBYTE
|
||
|
|
FFB0-A5 24 189 ( 3) LDA XAML Output low-order byte of address
|
||
|
|
FFB2-20 DC FF 190 ( 6) JSR PRBYTE
|
||
|
|
FFB5-A9 BA 191 ( 2) LDA #":" Print colon
|
||
|
|
FFB7-20 EF FF 192 ( 6) JSR ECHO
|
||
|
|
FFBA- 193
|
||
|
|
FFBA-A9 A0 194 ( 2) PRDATA LDA #" " Print space
|
||
|
|
FFBC-20 EF FF 195 ( 6) JSR ECHO
|
||
|
|
FFBF-A1 24 196 ( 6) LDA (XAML,X) Get data from address (X=0)
|
||
|
|
FFC1-20 DC FF 197 ( 6) JSR PRBYTE Output it in hex format
|
||
|
|
FFC4-86 2B 198 ( 3) XAMNEXT STX MODE 0 -> MODE (XAM mode).
|
||
|
|
FFC6-A5 24 199 ( 3) LDA XAML See if there's more to print
|
||
|
|
FFC8-C5 28 200 ( 3) CMP L
|
||
|
|
FFCA-A5 25 201 ( 3) LDA XAMH
|
||
|
|
FFCC-E5 29 202 ( 3) SBC H
|
||
|
|
FFCE-B0 C1 203 (2**) BCS TONEXTITEM Not less! No more data to output
|
||
|
|
FFD0- 204
|
||
|
|
FFD0-E6 24 205 ( 5) INC XAML Increment 'examine index'
|
||
|
|
FFD2-D0 02 206 (2**) BNE MOD8CHK No carry!
|
||
|
|
FFD4-E6 25 207 ( 5) INC XAMH
|
||
|
|
FFD6- 208
|
||
|
|
FFD6-A5 24 209 ( 3) MOD8CHK LDA XAML If address MOD 8 = 0 start new line
|
||
|
|
FFD8-29 07 210 ( 2) AND #%0000.0111
|
||
|
|
FFDA-10 C8 211 (2**) BPL NXTPRNT Always taken.
|
||
|
|
FFDC- 212
|
||
|
|
FFDC- 213 ;-------------------------------------------------------------------------
|
||
|
|
FFDC- 214 ; Subroutine to print a byte in A in hex form (destructive)
|
||
|
|
FFDC- 215 ;-------------------------------------------------------------------------
|
||
|
|
FFDC- 216
|
||
|
|
FFDC-48 217 ( 3) PRBYTE PHA Save A for LSD
|
||
|
|
FFDD-4A 218 ( 2) LSR
|
||
|
|
FFDE-4A 219 ( 2) LSR
|
||
|
|
FFDF-4A 220 ( 2) LSR MSD to LSD position
|
||
|
|
FFE0-4A 221 ( 2) LSR
|
||
|
|
FFE1-20 E5 FF 222 ( 6) JSR PRHEX Output hex digit
|
||
|
|
FFE4-68 223 ( 4) PLA Restore A
|
||
|
|
FFE5- 224
|
||
|
|
FFE5- 225 ; Fall through to print hex routine
|
||
|
|
FFE5- 226
|
||
|
|
FFE5- 227 ;-------------------------------------------------------------------------
|
||
|
|
FFE5- 228 ; Subroutine to print a hexadecimal digit
|
||
|
|
FFE5- 229 ;-------------------------------------------------------------------------
|
||
|
|
FFE5- 230
|
||
|
|
FFE5-29 0F 231 ( 2) PRHEX AND #%0000.1111 Mask LSD for hex print
|
||
|
|
FFE7-09 B0 232 ( 2) ORA #"0" Add "0"
|
||
|
|
FFE9-C9 BA 233 ( 2) CMP #"9"+1 Is it a decimal digit?
|
||
|
|
FFEB-90 02 234 (2**) BCC ECHO Yes! output it
|
||
|
|
FFED-69 06 235 ( 2) ADC #6 Add offset for letter A-F
|
||
|
|
FFEF- 236
|
||
|
|
FFEF- 237 ; Fall through to print routine
|
||
|
|
FFEF- 238
|
||
|
|
FFEF- 239 ;-------------------------------------------------------------------------
|
||
|
|
FFEF- 240 ; Subroutine to print a character to the terminal
|
||
|
|
FFEF- 241 ;-------------------------------------------------------------------------
|
||
|
|
FFEF- 242
|
||
|
|
FFEF-2C 12 D0 243 ( 4) ECHO BIT DSP DA bit (B7) cleared yet?
|
||
|
|
FFF2-30 FB 244 (2**) BMI ECHO No! Wait for display ready
|
||
|
|
FFF4-8D 12 D0 245 ( 4) STA DSP Output character. Sets DA
|
||
|
|
FFF7-60 246 ( 6) RTS
|
||
|
|
FFF8- 247
|
||
|
|
FFF8- 248 ;-------------------------------------------------------------------------
|
||
|
|
FFF8- 249 ; Vector area
|
||
|
|
FFF8- 250 ;-------------------------------------------------------------------------
|
||
|
|
FFF8- 251
|
||
|
|
FFF8-00 00 252 .DA $0000 Unused, what a pity
|
||
|
|
FFFA-00 0F 253 NMI_VEC .DA $0F00 NMI vector
|
||
|
|
FFFC-00 FF 254 RESET_VEC .DA RESET RESET vector
|
||
|
|
FFFE-00 00 255 IRQ_VEC .DA $0000 IRQ vector
|