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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 |