| 1 | /* altair_dsk.c: MITS Altair 88-DISK Simulator\r |
| 2 | \r |
| 3 | Copyright (c) 1997-2005, Charles E. Owen\r |
| 4 | \r |
| 5 | Permission is hereby granted, free of charge, to any person obtaining a\r |
| 6 | copy of this software and associated documentation files (the "Software"),\r |
| 7 | to deal in the Software without restriction, including without limitation\r |
| 8 | the rights to use, copy, modify, merge, publish, distribute, sublicense,\r |
| 9 | and/or sell copies of the Software, and to permit persons to whom the\r |
| 10 | Software is furnished to do so, subject to the following conditions:\r |
| 11 | \r |
| 12 | The above copyright notice and this permission notice shall be included in\r |
| 13 | all copies or substantial portions of the Software.\r |
| 14 | \r |
| 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\r |
| 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,\r |
| 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL\r |
| 18 | ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER\r |
| 19 | IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN\r |
| 20 | CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\r |
| 21 | \r |
| 22 | Except as contained in this notice, the name of Charles E. Owen shall not be\r |
| 23 | used in advertising or otherwise to promote the sale, use or other dealings\r |
| 24 | in this Software without prior written authorization from Charles E. Owen.\r |
| 25 | \r |
| 26 | The 88_DISK is a 8-inch floppy controller which can control up\r |
| 27 | to 16 daisy-chained Pertec FD-400 hard-sectored floppy drives.\r |
| 28 | Each diskette has physically 77 tracks of 32 137-byte sectors\r |
| 29 | each.\r |
| 30 | \r |
| 31 | The controller is interfaced to the CPU by use of 3 I/O addreses,\r |
| 32 | standardly, these are device numbers 10, 11, and 12 (octal).\r |
| 33 | \r |
| 34 | Address Mode Function\r |
| 35 | ------- ---- --------\r |
| 36 | \r |
| 37 | 10 Out Selects and enables Controller and Drive\r |
| 38 | 10 In Indicates status of Drive and Controller\r |
| 39 | 11 Out Controls Disk Function\r |
| 40 | 11 In Indicates current sector position of disk\r |
| 41 | 12 Out Write data\r |
| 42 | 12 In Read data\r |
| 43 | \r |
| 44 | Drive Select Out (Device 10 OUT):\r |
| 45 | \r |
| 46 | +---+---+---+---+---+---+---+---+\r |
| 47 | | C | X | X | X | Device |\r |
| 48 | +---+---+---+---+---+---+---+---+\r |
| 49 | \r |
| 50 | C = If this bit is 1, the disk controller selected by 'device' is\r |
| 51 | cleared. If the bit is zero, 'device' is selected as the\r |
| 52 | device being controlled by subsequent I/O operations.\r |
| 53 | X = not used\r |
| 54 | Device = value zero thru 15, selects drive to be controlled.\r |
| 55 | \r |
| 56 | Drive Status In (Device 10 IN):\r |
| 57 | \r |
| 58 | +---+---+---+---+---+---+---+---+\r |
| 59 | | R | Z | I | X | X | H | M | W |\r |
| 60 | +---+---+---+---+---+---+---+---+\r |
| 61 | \r |
| 62 | W - When 0, write circuit ready to write another byte.\r |
| 63 | M - When 0, head movement is allowed\r |
| 64 | H - When 0, indicates head is loaded for read/write\r |
| 65 | X - not used (will be 0)\r |
| 66 | I - When 0, indicates interrupts enabled (not used this simulator)\r |
| 67 | Z - When 0, indicates head is on track 0\r |
| 68 | R - When 0, indicates that read circuit has new byte to read\r |
| 69 | \r |
| 70 | Drive Control (Device 11 OUT):\r |
| 71 | \r |
| 72 | +---+---+---+---+---+---+---+---+\r |
| 73 | | W | C | D | E | U | H | O | I |\r |
| 74 | +---+---+---+---+---+---+---+---+\r |
| 75 | \r |
| 76 | I - When 1, steps head IN one track\r |
| 77 | O - When 1, steps head OUT out track\r |
| 78 | H - When 1, loads head to drive surface\r |
| 79 | U - When 1, unloads head\r |
| 80 | E - Enables interrupts (ignored this simulator)\r |
| 81 | D - Disables interrupts (ignored this simulator)\r |
| 82 | C - When 1 lowers head current (ignored this simulator)\r |
| 83 | W - When 1, starts Write Enable sequence: W bit on device 10\r |
| 84 | (see above) will go 1 and data will be read from port 12\r |
| 85 | until 137 bytes have been read by the controller from\r |
| 86 | that port. The W bit will go off then, and the sector data\r |
| 87 | will be written to disk. Before you do this, you must have\r |
| 88 | stepped the track to the desired number, and waited until\r |
| 89 | the right sector number is presented on device 11 IN, then\r |
| 90 | set this bit.\r |
| 91 | \r |
| 92 | Sector Position (Device 11 IN):\r |
| 93 | \r |
| 94 | As the sectors pass by the read head, they are counted and the\r |
| 95 | number of the current one is available in this register.\r |
| 96 | \r |
| 97 | +---+---+---+---+---+---+---+---+\r |
| 98 | | X | X | Sector Number | T |\r |
| 99 | +---+---+---+---+---+---+---+---+\r |
| 100 | \r |
| 101 | X = Not used\r |
| 102 | Sector number = binary of the sector number currently under the\r |
| 103 | head, 0-31.\r |
| 104 | T = Sector True, is a 1 when the sector is positioned to read or\r |
| 105 | write.\r |
| 106 | \r |
| 107 | */\r |
| 108 | \r |
| 109 | #include <stdio.h>\r |
| 110 | \r |
| 111 | #include "altair_defs.h"\r |
| 112 | \r |
| 113 | #define UNIT_V_ENABLE (UNIT_V_UF + 0) /* Write Enable */\r |
| 114 | #define UNIT_ENABLE (1 << UNIT_V_ENABLE)\r |
| 115 | \r |
| 116 | #define DSK_SECTSIZE 137\r |
| 117 | #define DSK_SECT 32\r |
| 118 | #define DSK_TRACSIZE 4384\r |
| 119 | #define DSK_SURF 1\r |
| 120 | #define DSK_CYL 77\r |
| 121 | #define DSK_SIZE (DSK_SECT * DSK_SURF * DSK_CYL * DSK_SECTSIZE)\r |
| 122 | \r |
| 123 | t_stat dsk_svc (UNIT *uptr);\r |
| 124 | t_stat dsk_reset (DEVICE *dptr);\r |
| 125 | void writebuf();\r |
| 126 | \r |
| 127 | extern int32 PCX;\r |
| 128 | \r |
| 129 | /* Global data on status */\r |
| 130 | \r |
| 131 | int32 cur_disk = 8; /* Currently selected drive */\r |
| 132 | int32 cur_track[9] = {0, 0, 0, 0, 0, 0, 0, 0, 377};\r |
| 133 | int32 cur_sect[9] = {0, 0, 0, 0, 0, 0, 0, 0, 377};\r |
| 134 | int32 cur_byte[9] = {0, 0, 0, 0, 0, 0, 0, 0, 377};\r |
| 135 | int32 cur_flags[9] = {0, 0, 0, 0, 0, 0, 0, 0, 0};\r |
| 136 | \r |
| 137 | char dskbuf[137]; /* Data Buffer */\r |
| 138 | int32 dirty = 0; /* 1 when buffer has unwritten data in it */\r |
| 139 | UNIT *dptr; /* fileref to write dirty buffer to */\r |
| 140 | \r |
| 141 | int32 dsk_rwait = 100; /* rotate latency */\r |
| 142 | \r |
| 143 | \r |
| 144 | /* 88DSK Standard I/O Data Structures */\r |
| 145 | \r |
| 146 | UNIT dsk_unit[] = {\r |
| 147 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 148 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 149 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 150 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 151 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 152 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 153 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) },\r |
| 154 | { UDATA (&dsk_svc, UNIT_FIX+UNIT_ATTABLE+UNIT_DISABLE, DSK_SIZE) }\r |
| 155 | };\r |
| 156 | \r |
| 157 | REG dsk_reg[] = {\r |
| 158 | { ORDATA (DISK, cur_disk, 4) },\r |
| 159 | { NULL }\r |
| 160 | };\r |
| 161 | \r |
| 162 | DEVICE dsk_dev = {\r |
| 163 | "DSK", dsk_unit, dsk_reg, NULL,\r |
| 164 | 8, 10, 31, 1, 8, 8,\r |
| 165 | NULL, NULL, &dsk_reset,\r |
| 166 | NULL, NULL, NULL\r |
| 167 | };\r |
| 168 | \r |
| 169 | /* Service routines to handle simlulator functions */\r |
| 170 | \r |
| 171 | /* service routine - actually gets char & places in buffer */\r |
| 172 | \r |
| 173 | t_stat dsk_svc (UNIT *uptr)\r |
| 174 | {\r |
| 175 | return SCPE_OK;\r |
| 176 | }\r |
| 177 | \r |
| 178 | /* Reset routine */\r |
| 179 | \r |
| 180 | t_stat dsk_reset (DEVICE *dptr)\r |
| 181 | {\r |
| 182 | cur_disk = 0;\r |
| 183 | return SCPE_OK;\r |
| 184 | }\r |
| 185 | \r |
| 186 | /* I/O instruction handlers, called from the CPU module when an\r |
| 187 | IN or OUT instruction is issued.\r |
| 188 | \r |
| 189 | Each function is passed an 'io' flag, where 0 means a read from\r |
| 190 | the port, and 1 means a write to the port. On input, the actual\r |
| 191 | input is passed as the return value, on output, 'data' is written\r |
| 192 | to the device.\r |
| 193 | */\r |
| 194 | \r |
| 195 | /* Disk Controller Status/Select */\r |
| 196 | \r |
| 197 | /* IMPORTANT: The status flags read by port 8 IN instruction are\r |
| 198 | INVERTED, that is, 0 is true and 1 is false. To handle this, the\r |
| 199 | simulator keeps it's own status flags as 0=false, 1=true; and\r |
| 200 | returns the COMPLEMENT of the status flags when read. This makes\r |
| 201 | setting/testing of the flag bits more logical, yet meets the\r |
| 202 | simulation requirement that they are reversed in hardware.\r |
| 203 | */\r |
| 204 | \r |
| 205 | int32 dsk10(int32 io, int32 data)\r |
| 206 | {\r |
| 207 | \r |
| 208 | if (io == 0) { /* IN: return flags */\r |
| 209 | return ((~cur_flags[cur_disk]) & 0xFF); /* Return the COMPLEMENT! */\r |
| 210 | }\r |
| 211 | \r |
| 212 | /* OUT: Controller set/reset/enable/disable */\r |
| 213 | \r |
| 214 | if (dirty == 1)\r |
| 215 | writebuf();\r |
| 216 | \r |
| 217 | /*printf("\n[%o] OUT 10: %x", PCX, data);*/\r |
| 218 | cur_disk = data & 0x0F;\r |
| 219 | if (data & 0x80) {\r |
| 220 | cur_flags[cur_disk] = 0; /* Disable drive */\r |
| 221 | cur_sect[cur_disk = 0377];\r |
| 222 | cur_byte[cur_disk = 0377];\r |
| 223 | return (0);\r |
| 224 | }\r |
| 225 | cur_flags[cur_disk] = 0x1A; /* Enable: head move true */\r |
| 226 | cur_sect[cur_disk] = 0377; /* reset internal counters */\r |
| 227 | cur_byte[cur_disk] = 0377;\r |
| 228 | if (cur_track[cur_disk] == 0)\r |
| 229 | cur_flags[cur_disk] |= 0x40; /* track 0 if there */\r |
| 230 | return (0);\r |
| 231 | }\r |
| 232 | \r |
| 233 | /* Disk Drive Status/Functions */\r |
| 234 | \r |
| 235 | int32 dsk11(int32 io, int32 data)\r |
| 236 | {\r |
| 237 | int32 stat;\r |
| 238 | \r |
| 239 | if (io == 0) { /* Read sector position */\r |
| 240 | /*printf("\n[%o] IN 11", PCX);*/\r |
| 241 | if (dirty == 1)\r |
| 242 | writebuf();\r |
| 243 | if (cur_flags[cur_disk] & 0x04) { /* head loaded? */\r |
| 244 | cur_sect[cur_disk]++;\r |
| 245 | if (cur_sect[cur_disk] > 31)\r |
| 246 | cur_sect[cur_disk] = 0;\r |
| 247 | cur_byte[cur_disk] = 0377;\r |
| 248 | stat = cur_sect[cur_disk] << 1;\r |
| 249 | stat &= 0x3E; /* return 'sector true' bit = 0 (true) */\r |
| 250 | stat |= 0xC0; /* set on 'unused' bits */\r |
| 251 | return (stat);\r |
| 252 | } else {\r |
| 253 | return (0); /* head not loaded - return 0 */\r |
| 254 | }\r |
| 255 | }\r |
| 256 | \r |
| 257 | /* Drive functions */\r |
| 258 | \r |
| 259 | if (cur_disk > 7)\r |
| 260 | return (0); /* no drive selected - can do nothin */\r |
| 261 | \r |
| 262 | /*printf("\n[%o] OUT 11: %x", PCX, data);*/\r |
| 263 | if (data & 0x01) { /* Step head in */\r |
| 264 | cur_track[cur_disk]++;\r |
| 265 | if (cur_track[cur_disk] > 76 )\r |
| 266 | cur_track[cur_disk] = 76;\r |
| 267 | if (dirty == 1)\r |
| 268 | writebuf();\r |
| 269 | cur_sect[cur_disk] = 0377;\r |
| 270 | cur_byte[cur_disk] = 0377;\r |
| 271 | }\r |
| 272 | \r |
| 273 | if (data & 0x02) { /* Step head out */\r |
| 274 | cur_track[cur_disk]--;\r |
| 275 | if (cur_track[cur_disk] < 0) {\r |
| 276 | cur_track[cur_disk] = 0;\r |
| 277 | cur_flags[cur_disk] |= 0x40; /* track 0 if there */\r |
| 278 | }\r |
| 279 | if (dirty == 1)\r |
| 280 | writebuf();\r |
| 281 | cur_sect[cur_disk] = 0377;\r |
| 282 | cur_byte[cur_disk] = 0377;\r |
| 283 | }\r |
| 284 | \r |
| 285 | if (dirty == 1)\r |
| 286 | writebuf();\r |
| 287 | \r |
| 288 | if (data & 0x04) { /* Head load */\r |
| 289 | cur_flags[cur_disk] |= 0x04; /* turn on head loaded bit */\r |
| 290 | cur_flags[cur_disk] |= 0x80; /* turn on 'read data available */\r |
| 291 | }\r |
| 292 | \r |
| 293 | if (data & 0x08) { /* Head Unload */\r |
| 294 | cur_flags[cur_disk] &= 0xFB; /* off on 'head loaded' */\r |
| 295 | cur_flags[cur_disk] &= 0x7F; /* off on 'read data avail */\r |
| 296 | cur_sect[cur_disk] = 0377;\r |
| 297 | cur_byte[cur_disk] = 0377;\r |
| 298 | }\r |
| 299 | \r |
| 300 | /* Interrupts & head current are ignored */\r |
| 301 | \r |
| 302 | if (data & 0x80) { /* write sequence start */\r |
| 303 | cur_byte[cur_disk] = 0;\r |
| 304 | cur_flags[cur_disk] |= 0x01; /* enter new write data on */\r |
| 305 | }\r |
| 306 | return 0;\r |
| 307 | }\r |
| 308 | \r |
| 309 | /* Disk Data In/Out*/\r |
| 310 | \r |
| 311 | int32 dsk12(int32 io, int32 data)\r |
| 312 | {\r |
| 313 | static int32 rtn, i;\r |
| 314 | static long pos;\r |
| 315 | UNIT *uptr;\r |
| 316 | \r |
| 317 | uptr = dsk_dev.units + cur_disk;\r |
| 318 | if (io == 0) {\r |
| 319 | if ((i = cur_byte[cur_disk]) < 138) { /* just get from buffer */\r |
| 320 | cur_byte[cur_disk]++;\r |
| 321 | return (dskbuf[i] & 0xFF);\r |
| 322 | }\r |
| 323 | /* physically read the sector */\r |
| 324 | /*printf("\n[%o] IN 12 (READ) T%d S%d", PCX, cur_track[cur_disk],\r |
| 325 | cur_sect[cur_disk]);*/\r |
| 326 | pos = DSK_TRACSIZE * cur_track[cur_disk];\r |
| 327 | pos += DSK_SECTSIZE * cur_sect[cur_disk];\r |
| 328 | rtn = fseek(uptr -> fileref, pos, 0);\r |
| 329 | rtn = fread(dskbuf, 137, 1, uptr -> fileref);\r |
| 330 | cur_byte[cur_disk] = 1;\r |
| 331 | return (dskbuf[0] & 0xFF);\r |
| 332 | } else {\r |
| 333 | if (cur_byte[cur_disk] > 136) {\r |
| 334 | i = cur_byte[cur_disk];\r |
| 335 | dskbuf[i] = data & 0xFF;\r |
| 336 | writebuf();\r |
| 337 | return (0);\r |
| 338 | }\r |
| 339 | i = cur_byte[cur_disk];\r |
| 340 | dirty = 1;\r |
| 341 | dptr = uptr;\r |
| 342 | dskbuf[i] = data & 0xFF;\r |
| 343 | cur_byte[cur_disk]++;\r |
| 344 | return (0);\r |
| 345 | }\r |
| 346 | }\r |
| 347 | \r |
| 348 | void writebuf()\r |
| 349 | {\r |
| 350 | long pos;\r |
| 351 | int32 rtn, i;\r |
| 352 | \r |
| 353 | i = cur_byte[cur_disk]; /* null-fill rest of sector if any */\r |
| 354 | while (i < 138) {\r |
| 355 | dskbuf[i] = 0;\r |
| 356 | i++;\r |
| 357 | }\r |
| 358 | /*printf("\n[%o] OUT 12 (WRITE) T%d S%d", PCX, cur_track[cur_disk],\r |
| 359 | cur_sect[cur_disk]); i = getch(); */\r |
| 360 | pos = DSK_TRACSIZE * cur_track[cur_disk]; /* calc file pos */\r |
| 361 | pos += DSK_SECTSIZE * cur_sect[cur_disk];\r |
| 362 | rtn = fseek(dptr -> fileref, pos, 0);\r |
| 363 | rtn = fwrite(dskbuf, 137, 1, dptr -> fileref);\r |
| 364 | cur_flags[cur_disk] &= 0xFE; /* ENWD off */\r |
| 365 | cur_byte[cur_disk] = 0377;\r |
| 366 | dirty = 0;\r |
| 367 | return;\r |
| 368 | }\r |