Questions tagged [mainframe]

for questions about retrocomputing mainframes or clusters

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59
votes
13answers
12k views

How big is a mainframe?

If you read about the history of computing, you'll hear how the first computers were "huge". You will often come across assertions that in the early days of commercial computing, a single computer ...
45
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10answers
10k views

Why did 1950s-60s computers have such wide words?

Modern general-purpose computers typically have a 64-bit word size, but looking back in time, we see narrower CPUs. In the early 80s, the 68000 dealt with 32-bit addresses but the ALU was only 16 bits ...
36
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13answers
7k views

Why were programs entered on punch cards instead of paper tapes?

Dale Fisk's Programming With Punched Cards is a fascinating account of programming in the days of punch cards. The fundamental dynamic was that early computers did not yet support timesharing. The ...
32
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9answers
10k views

What did code on punch cards do with the other six bits per column?

In the fifties and sixties, program source code was typically stored on punch cards, one card per line. The most common card format was the IBM 80 column by 12 row. For source code, this was commonly ...
30
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5answers
6k views

How was the C language ported to architectures with non-power-of-2 word sizes?

By the time the C language started to gain popularity outside of the PDP-11 circles (mid-1970s), mainframes with "weird" word sizes, and no capability to address individual bytes efficiently were ...
29
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6answers
4k views

History behind the text column restriction

In the old days, I remember we were told to never go beyond the 70'th column in the text editor (the actual value was usually something above 70, but less than 80). Further, at least in the program I ...
25
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1answer
2k views

Why was IBM's Scientific Subroutine Package superseded?

It is a familiar fact that scientific software tends to do a lot of vector arithmetic and similar, that one does not want to keep rewriting the low-level code for such, so the usual practice is to use ...
24
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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 ...
23
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4answers
4k views

What accounted for the cost of ENIAC?

I'm used to the fact that first-generation computers were very expensive, which I had always assumed was because they contained large numbers of vacuum tubes, each of which is a rather complex, high ...
22
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7answers
5k views

What was the last non-monolithic CPU to come to market?

This answer to the question "What was the rationale behind 36 bit computer architectures?" makes the point that early computers were assembled by hand, rather than having central processing ...
20
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17answers
4k views

Were any IBM mainframes ever run multiuser?

Now of course there is a sense in which they were – some mainframe installations supported thousands of users! But there is a distinction. Consider the familiar fixture in so many 80s computer science ...
20
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5answers
5k views

Why did mainframes have big conspicuous power-off buttons?

Some fascinating stories in this discussion thread. It starts with discussion about computers overheating, but about halfway through the thread, it switches to discussion of mainframe installations in ...
20
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7answers
4k views

What was the most critical supporting software for COBOL on IBM mainframes?

Over the past half-century, one of the largest trends in the computer industry has been the replacement of mainframes by microcomputers. Not total by any means – there are still many mainframes in ...
19
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1answer
543 views

Was the IBM S/360 Responsible for Popularizating the 'A'-to-'F' Notation in Hexadecimal Numbers?

In the early history of computing before the mid-1960s, there wasn't an universal, de-facto standard for the written representation of a hexadecimal number, different computer systems used their own ...
17
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1answer
1k views

How did SABRE work interactively without screens?

The SABRE airline reservation system went online in 1964, astonishing the world by being among other things the first large-scale interactive computing system. Once the IBM 3270 video terminals were ...
15
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5answers
2k views

Was there ever a genuine “mainframe-on-a-chip” microprocessor?

In the 1980s and 90s, there was a fad among the IT industry press to dub the newest "hot" microprocessor on the market as being a "mainframe-on-a-chip". I have seen this fawning description applied to ...
15
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2answers
1k views

IBM mainframe classic executable file formats

Most modern platforms have pretty well-defined file formats; e.g. Windows uses PE, Linux and BSD - ELF (previously a.out), macOS - Mach-O, AIX - XCOFF and so on. What were (are?) common executable ...
15
votes
3answers
772 views

Is there a line printer sound simulator?

To improve "authenticity" of a mainframe simulator and for an additional nostalgic effect, I'd like to add sounds of a line printer to it. They should be similar enough to the original sounds for ...
14
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3answers
845 views

Which programming systems used object files on punch cards?

In a batch programming system developed in the late 1960s - early 1970s at the Joint Institute for Nuclear Research in the city of Dubna near Moscow, it was possible to dump object files to punch ...
14
votes
1answer
721 views

What's the deal with System/360's “USASCII” mode?

The original System/360 architecture had a bit in the Program Status Word that would select an "USASCII" mode rather than the usual EBCDIC. Setting this bit changed how the BCD arithmetic operations ...
13
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2answers
2k views

What is the purpose of the yellow wired panels on the IBM 360 Model 20?

I just finished reading a story about an IBM 360 Model 20 rescue, and some of the pictures caught my eye. Specifically this one: Searching online, led me to several more pictures, all with ...
13
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2answers
587 views

Do any interesting POP-2 programs survive?

On a disk image (which I had for many years) from a BESM-6, I've suddenly found a working POP-2 (POPLAN) interpreter (for all these years I'd considered that area as useless bits and pieces of various ...
13
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1answer
618 views

What is the prototype of the Eastern Bloc videoterminal Videoton 340?

Several decades ago, the Hungarian company "Videoton" manufactured a videoterminal for which I couldn't find a Western prototype. It likely existed, as the device had been assigned a "ES" number, ...
11
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4answers
3k views

Were round punchcard holes mechanically stiffer?

The most common punch card format was the IBM 80 column by 12 row, with narrow rectangular holes. However, there were other possibilities, such as a later IBM format that used round holes. That one ...
11
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2answers
1k views

Did any 360-compatible machine implement registers in core?

In the early days of transistors, when they cost on the order of a dollar each, it was possible to implement CPU registers with magnetic cores (the technology used for main memory at the time) instead ...
11
votes
1answer
406 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
276 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
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10answers
3k views

How did dusty deck Fortran handle overflow?

In Fortran 77, numerical code that ran on IBM, CDC, Cray etc, how was overflow typically handled? Did it raise an exception? (I would expect such an exception to be inexact on vector machines, i.e. to ...
9
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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, ...
9
votes
3answers
955 views

Patent barriers to IBM mainframe compatibility?

'Blue Magic: The People, Power and Politics Behind the IBM Personal Computer' is an excellent book, but it makes one claim I cannot quite make sense of. Page 13 of the hardback edition says: "Lowe ...
9
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2answers
330 views

Information about Sabre-ADS Model 757 terminal

Someone on reddit acquired a Sabre-ADS terminal, Model 757. They were used for airline reservation and probably connected to an IBM mainframe. Is there anything known about the pinout and workings of ...
8
votes
3answers
530 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
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1answer
845 views

How many transistors in the CDC 1604?

The CDC 1604, released in 1960, was Seymour Cray's first supercomputer, and also one of the first computers made of transistors. (The IBM 7090 was released only the previous year.) How many ...
7
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5answers
745 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
4answers
737 views

Connect IBM 3481 terminal to RS232?

I recently acquired an IBM 3481 terminal. It has a parallel port, a DB-15 port (I believe for a twinax-T connector), an 8P8C keyboard connector, and a PS/2 connector. Since I don't have a vintage IBM ...
6
votes
1answer
194 views

What information was present in line printer printout cover/trailer?

Nowadays, in corporate offices where there are typically several office printers per floor, sending a file to a printer does not result in any additional pages identifying the print job, at least by ...
6
votes
2answers
265 views

Documents about timesharing systems, access and resource control and its financials

I delved a bit into the origins of (commercial) timesharing and it seems there have been very interesting computing hardware and software (architectures) which have become relatively unknown but may ...
6
votes
2answers
404 views

Why did the CDC 6600 expand the word size to 60 bits?

According to http://www.quadibloc.com/comp/cp0201.htm The CDC 1604 used 48-bit floating point with 11 bits exponent and 36 bits mantissa. There was also a double precision format (which I believe was ...
6
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2answers
1k views

What specific factor(s) made Thomas Watson, Jr. (of IBM) so enthusiastic about early electronics?

One of my favourite computer history books is Stan Augarten's "Bit by Bit", which has an author-approved scanned copy at http://ds-wordpress.haverford.edu/bitbybit/ In it, the author makes ...
6
votes
1answer
258 views

Total weight of the CDC 7600?

I'm doing some research on the CDC 7600 supercomputer. I'm trying to find at least a general guess on the overall weight of the machine, preferably including the necessary cooling equipment. I know it ...
6
votes
1answer
416 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; ...
6
votes
1answer
300 views

Did other computer companies need to license Fortran from IBM?

Reading a fascinating online book about the history of computing, I came across this passage on http://ds-wordpress.haverford.edu/bitbybit/bit-by-bit-contents/chapter-seven/7-5-assembly-language-...
6
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1answer
428 views

When were floating point rounding modes first implemented?

It appears that at least some pre-IEEE 754 computers had only one hardwired floating point rounding mode, e.g. away from zero as in PDP-11 (page 154 of PDF). Which historical architectures were the ...
5
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3answers
1k views

How was it possible to run IBM mainframe software in emulation on HP?

... At least, without getting sued into the ground? According to one of the answers to What was the most critical supporting software for COBOL on IBM mainframes? We installed a new HP replacing an ...
5
votes
3answers
384 views

Is this a custom NASA Langley-built computer or is this a commercial system (ca 1970's)?

CNN's NASA will name its headquarters after Mary W. Jackson, the agency's first African American female engineer and NASA news item NASA Names Headquarters After ‘Hidden Figure’ Mary W. Jackson ...
5
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2answers
434 views

Data length module of 3.2^n confusion in IBM system/360 architecture

I'm currently reading about the IBM system/360 architecture and there's a part that has me very confused: The decision on basic format (which affected character size, word size, instruction field, ...
5
votes
2answers
948 views

Were any vacuum tube computers built with wire wrap?

I'm trying to gain some understanding of how early computers were built; as discussed in What accounted for the cost of ENIAC? the cost of first-generation computers was not necessarily mostly about ...
5
votes
0answers
155 views

Why did the Burroughs 205 not use bi-quinary like the IBM 650?

The IBM 650, one of the first general-purpose digital computers, designed in the early fifties, used decimal digits with bi-quinary representation for reasons discussed here: Why did the IBM 650 use ...
4
votes
4answers
447 views

IBM Mainframe APL internals?

The APL language used a unique set of characters, and additionally allowed overstriking of some characters on the terminal to form characters that were used in the language. When an APL workspace was ...
4
votes
2answers
390 views

Was sneakernet a job description?

'Sneakernet' is a colloquial term for moving data by walking back and forth with a removable digital medium such as a floppy disk or tape in your hand. In 'IBM's 360 and Early 370 Systems', page 533, ...