90:
27:
273:
250:
was used when the total memory demand for all processes exceeded the available physical memory. The operating system also took advantage of the 15 registers to reduce time required to change program environments. The successor to MAX IV, developed to fully exploit the
Modcomp Classic system, was
263:
system also was designed to take advantage of the multiple registers to temporarily hold the values of variables and indexes. The compiler also had optimization which reduced the number of operations required to process math expression most often found in indexing into arrays. The compiler also
207:. Beginning in 1978, the Modcomp IV was replaced by the Modcomp Classic; the first Classic model was the 7810. This retained compatibility with the Modcomp IV, while offering full support for 32-bit addressing. The later 9250 and 9260 continued to support both 16-bit and 32-bit applications.
311:
Outside of the aerospace industry, these systems were particularly popular with the oil industry, both in oil refineries and in oilfields, and for general manufacturing automation. Standard Oil, and Shell oil, made extensive use of
Modcomp equipment in the 1970s.
264:
produced Macro-Code that when processed by the Macro-Assembler produced loadable machine code. When the
Modcomp IV was released, the output of the compiler's code could be modified to take advantage of newer instructions available in the hardware.
141:
with an 800 ns cycle time, expandable to 128 kilobytes (131,072 bytes). The
Modcomp I followed for smaller applications, with only 3 general-purpose registers and a maximum of 64 kilobytes (65,536 bytes) of core. These machines were based on
296:
mainframe. In the 1990s
Modcomp developed a product in the UK called ViewMax, which was used to connect web-based "front-ends" to legacy systems. In 1996, Modcomp had $ 36.7 million in sales, and were purchased by
136:
Their first computer was the 16-bit
Modcomp III, introduced shortly after the company was founded. This had 15 general-purpose registers, and was initially offered with a 16-kilobyte (16,384 bytes), 18-mil
223:. MAX II was a batch disk operating system with real-time extensions. It could be used for program development in the background while foreground processes handled real-time loads. These systems used
230:
MAX III (for the 16-bit machines) and MAX IV (for the
Modcomp IV) allowed for multiple interactive users. In MAX III, all processes shared the one address space with swapping used to support multiple
168:
introduced in 1974. The minimum memory configuration was 32 kilobytes (32,768 bytes), expandable to 512 kilobytes (524,288 bytes), with access times of 500 to 800 nanoseconds (varying because of
504:
354:, Modular Computer Systems Inc, undated advertising brochure; discusses the Modcomp I, II. II/CP and IV computers. Therefore, the probable date is 1974–1975. Digitized Mar 18, 2009.
116:. In the 1970s and 1980s, they produced a line of 16- and 32-bit mini-computers. Through the 1980s, Modcomp lost market share as more powerful micro-computers became popular, and
494:
128:
systems continued to grow. The company successfully survives today as a systems integrator operating as CSPi
Technology Solutions headquartered in Deerfield Beach, Florida.
499:
489:
176:
of 256 pages each (some of these page tables could be further subdivided if address spaces smaller than 128 kilobytes (131,072 bytes) were needed). Fields of the
234:, one per interactive user. The MAX IV operating system was largely compatible, while it took advantage of the new features of the Modcomp IV to allocate one
509:
172:). The machine had 240 general purpose registers, addressable as 16 banks of 15 registers. The MMU contained 1024 address mapping registers, arranged as 4
219:
supported these machines. MAX I was a real-time monitor for a fixed set of processes linked into a single memory image. This met the requirements of many
514:
224:
474:
150:
366:, University of California at San Francisco, 1976; this is a third-party programmer's pocket reference card for the Modcomp IV.
430:
Mark F. Kempf, D'Arcy C. Randall, Timothy R. Walworth, Digital bus and control circuitry for data routing and transmission,
117:
470:
147:
113:
73:
154:
143:
204:
165:
153:. The Modcomp II, introduced in 1972, maintained compatibility with the Modcomp III, while using some
450:
181:
138:
239:
200:
185:
177:
109:
180:
were used to select the current active register bank and page table. The machine had a two-stage
231:
169:
284:
space probes, and in the 1980s they provided a network of 250 Modcomp II systems to control the
388:
332:
292:
as well as SET at SAIL at JSC until T-30, at which point control was handed over to a single
216:
161:
and provisions for physical modularity that hint at the reasoning behind the company name.
220:
203:
was limited to 64K 16-bit words; 256 pages of 256 words each, from the perspective of the
289:
89:
157:
circuits. The core architecture of the 16-bit machines included blocks of uncommitted
483:
400:
William M. Herring, Dennis B. Walling, Multiplexer-analog/digital
Conversion System,
285:
243:
235:
196:
331:
Marshall
William McMurran, "NASA Control Computers" (chapter 6), section "Modcomp",
105:
376:
387:
National Research Council, Chapter 7 — Computers, Steering, and Beam Pointing,
432:
417:
402:
173:
351:
305:
125:
363:
93:
Front panel of the Modcomp Classic (ACONIT collection in Grenoble, France)
26:
280:
Many of Modcomp's early sales were for tracking and data collection from
464:
272:
260:
191:
In many regards, the Modcomp IV had potential as a competitor for the
457:
247:
158:
164:
The Modcomp IV was an upward compatible 32-bit machine with a paged
451:
https://web.archive.org/web/20080321013737/http://www.modcomp.com/
308:
radar system built for the United States Air Force Space Command.
271:
88:
415:
William M. Herring, Dennis B. Walling, Computer Control System,
281:
293:
192:
121:
304:
Modcomp IV computers were used for the control system of the
298:
259:In addition to a very capable Macro-Assembler, the
79:
57:
49:
41:
33:
389:Radiation Intensity of the PAVE PAWS Radar System
505:Defunct computer companies of the United States
391:, National Academy of Sciences, 1979; page 33.
215:The Modular Applications eXecutive family of
8:
19:
495:Companies based in Fort Lauderdale, Florida
112:applications. They were founded in 1970 in
347:
345:
343:
327:
325:
25:
18:
321:
500:Computer companies established in 1970
490:American companies established in 1970
225:fixed-priority pre-emptive scheduling
7:
510:Defunct computer hardware companies
515:Defunct computer systems companies
16:1970s/1980s US minicomputer vendor
14:
475:photos of Modcomp Classic Systems
276:Front panel of a NASA Modcomp II
467:(near the bottom of the page).
337:, Xlibris, 2008; pages 161–162
1:
465:photos of a larger Modcomp II
463:Another collector has posted
364:Modcomp Max IV Reference Data
118:Digital Equipment Corporation
458:photographs of a Modcomp II
108:vendor that specialized in
63:; 54 years ago
531:
471:Levins Technologies, Inc.
178:Program Status Doubleword
83:CSPi Technology Solutions
24:
421:, granted Jan. 25, 1977.
114:Fort Lauderdale, Florida
102:Modular Computer Systems
74:Fort Lauderdale, Florida
37:Modular Computer Systems
456:A collector has posted
436:, granted Jul. 6, 1976.
406:, granted Jul. 6, 1976.
246:was not supported, and
449:The company web site:
277:
166:memory management unit
94:
433:U.S. patent 4,320,452
418:U.S. patent 4,005,387
403:U.S. patent 3,968,487
275:
92:
232:background processes
139:magnetic-core memory
378:, previous employee
255:Program development
186:floating-point unit
170:memory interleaving
21:
334:Achieving Accuracy
288:launch complex at
278:
95:
217:operating systems
211:Operating systems
87:
86:
522:
437:
435:
428:
422:
420:
413:
407:
405:
398:
392:
385:
379:
373:
367:
361:
355:
349:
338:
329:
221:embedded systems
71:
69:
64:
29:
22:
530:
529:
525:
524:
523:
521:
520:
519:
480:
479:
446:
441:
440:
431:
429:
425:
416:
414:
410:
401:
399:
395:
386:
382:
375:Felix Bearden,
374:
370:
362:
358:
350:
341:
330:
323:
318:
270:
257:
251:called MAX 32.
213:
195:, although the
134:
67:
65:
62:
17:
12:
11:
5:
528:
526:
518:
517:
512:
507:
502:
497:
492:
482:
481:
478:
477:
468:
461:
454:
445:
444:External links
442:
439:
438:
423:
408:
393:
380:
368:
356:
352:Modcomp Family
339:
320:
319:
317:
314:
290:Cape Canaveral
269:
266:
256:
253:
212:
209:
133:
130:
104:, was a small
85:
84:
81:
77:
76:
59:
55:
54:
51:
47:
46:
43:
39:
38:
35:
31:
30:
15:
13:
10:
9:
6:
4:
3:
2:
527:
516:
513:
511:
508:
506:
503:
501:
498:
496:
493:
491:
488:
487:
485:
476:
472:
469:
466:
462:
459:
455:
452:
448:
447:
443:
434:
427:
424:
419:
412:
409:
404:
397:
394:
390:
384:
381:
377:
372:
369:
365:
360:
357:
353:
348:
346:
344:
340:
336:
335:
328:
326:
322:
315:
313:
309:
307:
302:
300:
295:
291:
287:
286:Space Shuttle
283:
274:
267:
265:
262:
254:
252:
249:
245:
244:Demand paging
241:
237:
236:address space
233:
228:
226:
222:
218:
210:
208:
206:
202:
198:
197:address space
194:
189:
187:
183:
179:
175:
171:
167:
162:
160:
156:
152:
149:
145:
140:
131:
129:
127:
123:
119:
115:
111:
107:
103:
100:, originally
99:
98:Modcomp, Inc.
91:
82:
78:
75:
60:
56:
53:Minicomputers
52:
48:
44:
40:
36:
32:
28:
23:
426:
411:
396:
383:
371:
359:
333:
310:
303:
279:
268:Applications
258:
229:
214:
190:
163:
135:
106:minicomputer
101:
97:
96:
42:Company type
184:CPU, and a
174:page tables
484:Categories
316:References
306:PAVE PAWS
238:for each
182:pipelined
151:TTL logic
132:Computers
110:real-time
80:Successor
248:swapping
50:Industry
34:Formerly
261:Fortran
240:process
201:process
159:opcodes
66: (
58:Founded
45:Private
20:Modcomp
126:Alpha
473:has
299:CSPI
282:NASA
199:per
146:and
124:and
68:1970
61:1970
294:IBM
242:.
205:MMU
193:VAX
155:LSI
148:MSI
144:SSI
122:VAX
120:'s
72:in
486::
342:^
324:^
301:.
227:.
188:.
460:.
453:.
70:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
