Questions tagged [mainframe]

for questions about retrocomputing mainframes or clusters

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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 ...
MathematicalOrchid's user avatar
49 votes
10 answers
11k 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 ...
rwallace's user avatar
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37 votes
13 answers
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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 ...
rwallace's user avatar
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34 votes
9 answers
11k 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 ...
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31 votes
5 answers
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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 ...
Leo B.'s user avatar
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29 votes
6 answers
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 ...
Burhan Khalid's user avatar
29 votes
2 answers
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Why was IBM's Scientific Subroutine Package superseded?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 ...
rwallace's user avatar
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27 votes
1 answer
7k 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 ...
rwallace's user avatar
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26 votes
7 answers
5k 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 ...
rwallace's user avatar
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25 votes
7 answers
6k 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 ...
DrSheldon's user avatar
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24 votes
4 answers
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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 ...
rwallace's user avatar
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23 votes
5 answers
6k 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 ...
rwallace's user avatar
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23 votes
1 answer
896 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 was no universal, de-facto standard for the written representation of a hexadecimal number, different computer systems used their own ...
比尔盖子's user avatar
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21 votes
17 answers
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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 ...
rwallace's user avatar
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21 votes
7 answers
4k views

References for the complexity of the COBOL language

One thing that struck me about the design of COBOL was that it was surprisingly complex, particularly for the era. As in, if I were trying to squeeze a compiler into a few tens of kilobytes of memory, ...
rwallace's user avatar
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21 votes
1 answer
3k views

What date is 74029 on an IBM Mainframe?

I have an old printout of a Fortran code. It's a simple code intended for educational purposes. The header is: FORTRAN IV G LEVEL 21, MAIN, DATE=74029, 15/28/03, PAGE 001 I assume it's from an IBM ...
Hanan Cohen's user avatar
19 votes
4 answers
1k 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 ...
Leo B.'s user avatar
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18 votes
5 answers
3k 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 ...
Brian H's user avatar
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17 votes
2 answers
4k views

Was bootloading from punch cards possible on System/370 machines?

I have been idly looking into how System 370 works, though mostly at software and VM/370 OS. As a part of the system generation process, one needs to use DMKDDR utility and others. So I was curious ...
Saphire's user avatar
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17 votes
1 answer
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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 ...
rwallace's user avatar
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16 votes
7 answers
3k views

Was any indentation-sensitive language ever used with a teletype or punch cards?

Most programming languages delimit block structure with punctuation e.g. { ... } or keywords e.g. begin ... end. However, some languages such as Python and Haskell delimit it with indentation (...
rwallace's user avatar
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16 votes
3 answers
990 views

Why did instruction sets since the late 1970s seemingly stop including an "execute" instruction?

Many mainframe instruction set architectures (ISAs) in the 1960s included an Execute instruction, which would treat data as an instruction. I haven't found an architecture designed after 1976 which ...
Stavros Macrakis's user avatar
16 votes
0 answers
828 views

Was there a cartoon series in the UK computer press called "Computability Brown"?

My dad was a computing professional in Scotland in the 1970s. He received a couple of industry trade magazines every week, such as Computer Weekly and Computing. In one of them, I remember there being ...
scruss's user avatar
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15 votes
2 answers
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 ...
Igor Skochinsky's user avatar
14 votes
2 answers
507 views

Can anyone help me identify this old computer part?

I purchased two identical computer parts at an estate sale that seemed unusual. I was told that perhaps it was a component from an old IBM mainframe. I was able to date them between late 50's and ...
user avatar
14 votes
1 answer
2k views

What is a good COBOL specification to target when aiming to support ~75% or more of mainframe and minicomputer software bases?

There are many specifications for COBOL due to its long history. If one wanted to write software that would be acceptable for use in about 75% or more of existing COBOL projects on mainframes or ...
bbarker's user avatar
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14 votes
2 answers
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 ...
Bradley Uffner's user avatar
14 votes
3 answers
1k 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 ...
Leo B.'s user avatar
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14 votes
1 answer
892 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 ...
hmakholm left over Monica's user avatar
14 votes
2 answers
659 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 ...
Leo B.'s user avatar
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13 votes
4 answers
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 ...
rwallace's user avatar
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13 votes
1 answer
865 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, ...
Leo B.'s user avatar
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12 votes
4 answers
2k views

History of High Availability in the mainframe and minicomputer eras?

When tracing the source of High Availability, I found to my surprise it led to a company named Tandem Computers which since 1974 made a series of minicomputers called NonStop system, to my surprise ...
Schezuk's user avatar
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12 votes
4 answers
637 views

Does anyone have any information on GUTS (Gothenburg University Timesharing System)?

Gothenburg Universities Computer Centre (in Sweden) developed a timesharing system for IBM mainframes, known as GUTS (variously expanded either as ''Gothenburg University Timesharing System'', or as ''...
Simon Kissane's user avatar
12 votes
2 answers
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 ...
rwallace's user avatar
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12 votes
1 answer
1k 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 ...
Simon Kissane's user avatar
11 votes
6 answers
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, ...
rwallace's user avatar
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11 votes
3 answers
1k 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 ...
rwallace's user avatar
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11 votes
2 answers
1k views

Why did IBM want to keep ICL alive?

According to https://en.wikipedia.org/wiki/International_Computers_Limited International Computers Limited (ICL) was a British computer hardware, computer software and computer services company that ...
rwallace's user avatar
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10 votes
1 answer
1k views

Did the IBM 1401 have much better code density than the 360?

Reading an old thread https://groups.google.com/g/alt.folklore.computers/c/53C2adEQ5jE I see a surprising claim: I told an IBM salesman once that IBM had so bollixed up the architecture that our ...
rwallace's user avatar
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10 votes
1 answer
765 views

What is the mainframe in this image in Ireland?

Someone recently posted this image of his gran (on the right). Mainframes were before my era, can anyone positively identify the model? I don't see a console in the image, which is where I would ...
Maury Markowitz's user avatar
10 votes
2 answers
539 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 ...
rwallace's user avatar
  • 61k
10 votes
1 answer
442 views

What sort of intermediate representation did the first Fortran compiler use?

Proebsting's Law asserts that improvements to compiler technology double the performance of typical programs every 18 years, but even granted that this is somewhat tongue-in-cheek, it's not really ...
rwallace's user avatar
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9 votes
9 answers
5k views

Why did the VT100 terminal have to be connected to a host computer if it already had a processor?

The VT100 terminal already had an 8080 processor. So why did it have to be connected to a host computer? Why not use its processor to perform computations? Is it because the VT100 processor's purpose ...
Noob_Guy's user avatar
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9 votes
10 answers
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 ...
rwallace's user avatar
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9 votes
6 answers
715 views

Besides the IBM 709 and its descendents, did any other machine have "slightly longer" registers?

This question occurred to me while I was formulating this answer about arithmetic versus logical shifts. The IBM 709, and its descendant the 7090, etc., is a 36-bit mainframe with a classical single-...
dave's user avatar
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9 votes
2 answers
1k views

What was the second platform supported by SAP?

SAP, the well-known ERP software company, started out in the 1970s, with the first version of their software running on IBM mainframes, https://en.wikipedia.org/wiki/SAP_R/2 What was unique about R/2 ...
rwallace's user avatar
  • 61k
9 votes
1 answer
1k 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 ...
rwallace's user avatar
  • 61k
9 votes
1 answer
737 views

Why did IBM skip "System/380" as a mainframe family name?

I've been reading Exhibit 14971 from US vs. IBM (Parts 1, 2, 3) which seems to give a very good overview of the history of the computer industry up to 1980, particularly the way IBM handled its ...
Wildcat Matt's user avatar
9 votes
2 answers
416 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 ...
dirkt's user avatar
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