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