Questions tagged [minicomputers]

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24
votes
1answer
6k views

What was the first operating system called DOS?

MS-DOS a.k.a. PC-DOS nee QDOS, was commonly just referred to as DOS. But 'disk operating system' is a very obvious acronym; there must have been previous operating systems so called. What was the ...
22
votes
1answer
667 views

Reconstruct the loop from “The Story of Mel”

From Ed Nather's hacker-epic "The Story of Mel" (using the original paragraph-formatting to save space in this question): The firm manufactured the LGP-30, a small, cheap (by the standards ...
17
votes
1answer
1k views

How did the Nova 1200 divide so quickly?

According to https://en.wikipedia.org/wiki/Data_General_Nova The Nova 1200 executed core memory access instructions (LDA and STA) in 2.55 microseconds (μs). Use of read-only memory saved 0.4 μs. ...
16
votes
4answers
5k views

Why are old computers so vulnerable to temperature changes and moisture?

Interesting discussion by someone thinking of procuring a PDP-11/34, though having difficulty finding suitable space for it: https://www.reddit.com/r/retrobattlestations/comments/dztvci/...
13
votes
5answers
1k views

Has there ever been a instruction set architecture that did not require instruction decoding at all?

I am studying basic principles of instruction set architectures and am considering what it would take to not have any instruction decoding at all. I.e., all the control lines of the computer would be ...
11
votes
1answer
413 views

Why did IBM develop 5250 block mode terminals when 3270 already existed?

IBM introduced the 3270 family of block mode terminals in 1971, for use with IBM mainframes (System/370 and successors). Then, in 1977, IBM introduced the 5250 family of block mode terminals for use ...
10
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2answers
2k views

Did the PDP-8 designers consider a stack?

The PDP-8 was a remarkable exercise in minimalist computer design; some of the aspects of its design are discussed in detail at PDP-8 transistor count One feature it did not have was a stack. Instead, ...
10
votes
2answers
281 views

Did any core-memory computers have a read-and-erase instruction?

Magnetic core, the primary form of computer memory from the mid-fifties to the early seventies or thereabouts, had the slightly awkward property that reading it erased it, so every time the CPU ...
9
votes
6answers
1k views

What did order processing on a teletype look like?

The earliest business data processing systems were based on batch processing of punchcards. Prepare cards off-line, feed a batch of them through the computer. (Why does one so often hear of payroll, ...
8
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3answers
2k views

Floating point performance of classic minicomputers

Are there any numbers available for the floating point performance of classic minicomputers of the seventies and eighties? For example, the VAX 11/780 for integer calculations was generally rated in ...
8
votes
3answers
536 views

Uh, oh, I've woken up in 1973. Can I get a job in computing? [closed]

I've woken up in 1973. Until I can figure out how to monetize my knowledge of coming political, economic, and social trends, I need to support myself somehow. So... I walk into one of the major ...
8
votes
1answer
530 views

Typical mid-scale business computer system of the late 70s

What was the most common business computer system of the late 70s, just before the Apple II and CP/M really started proliferating? For concreteness, let's say we are talking about a U.S. company on ...
7
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5answers
746 views

When did smart terminals arrive?

In the days of mainframes and minicomputers, a common user interface was a serial terminal where each keystroke was sent to the computer, which could respond with an update to the contents of the ...
6
votes
1answer
1k views

What programming languages were most commonly used on the AS/400 in the 90s?

The IBM AS/400, formerly known as System/38, subsequently known as i (sic), is remarkable in being essentially the most future-proof of all the minicomputers, thanks among other things to the use of ...
6
votes
1answer
417 views

How many hours of labor did it take to assemble a minicomputer?

A minicomputer like the PDP-8 contained several thousand discrete transistors and other components, all of which had to be soldered by hand, and that was among the simplest computers on the market; ...
5
votes
3answers
946 views

Indirect addressing using address bits as marker (tagged address)

After reading about the Signetics 2650, and being a bit familiar with the HP2100's, I'm curious how common the style of "indirect addressing via the address value" instruction was at the time? CPUs ...
3
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2answers
397 views

Trying to recall an OS I worked on that was called CPM but was not DR's CP/M

I'm trying to trace a type of system I did a little work on in my first job, which was for a company which no longer exists and I am not in regular touch with most of my former colleagues. It was a ...
3
votes
1answer
153 views

What was the first company to sell an IBM compatible punchcard reader?

Punchcards were the primary way to get information into computers up through the sixties. The familiar eighty column format was designed by IBM, and was a factor in the later de facto standard eighty ...
3
votes
1answer
237 views

Can I restore an S/38 program to a current IBM i?

The IBM System/38 or just S/38 was an IBM mini-computer launched in 1978. I don't know when IBM stopped marketing it but their AS/400 was released in 1988 and it was very easy to switch from the S/38 ...