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

The basic issue that paper tape is hard to edit. In theory you can cut the existing tape and splice in a new section, but in practice there is no easy way to find the correct location except by ...
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  • 6,385
75 votes
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Why did 1950s-60s computers have such wide words?

And if you go back further, e.g. to the ENIAC, you'll see a word size of 40 bits. And if you go back even further, to mechanical calculators, you'll see word sizes determined by the number of decimal ...
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74 votes
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How big is a mainframe?

In the 1980's a certain bank with its headquarters in Edinburgh has a problem with (IBM) disc storage that had to be kept online for live customer account information for branch and ATM machine ...
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57 votes
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What was the first operating system called DOS?

DOS/360 (As distinct from TOS/360, the tape OS) Announced at the end of 1964 per Wikipedia.
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  • 28.3k
54 votes

What accounted for the cost of ENIAC?

R&D stuff isn't manufactured (at first). It's usually partially constructed, ripped up, and redone, multiple times, with long testing and debug cycles in between, all the while with payroll ...
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  • 7,814
53 votes
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History behind the text column restriction

Old COBOL standards were based around 80-column punched cards, and columns beyond 71 (or 72) were reserved for line numbers. They were little used, but a numbered deck, if dropped, could be sorted by ...
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  • 2,779
51 votes
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What did code on punch cards do with the other six bits per column?

TL;DR; Punch card code is not binary but a collection of n out of m encodings. Long Story Yes, really a long story, so I'll only cover the main line from Hollerith to EBCDIC. There are many sidelines ...
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  • 173k
41 votes
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Why was IBM's Scientific Subroutine Package superseded?

Specifically concerning EISPACK. what happened was that James Hardy "Jim" Wilkinson in the UK (whose career as an applied mathematician started with practical ballistic modelling in WWII, ...
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  • 6,385
37 votes

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

Punch cards long long long predated paper tape. But there's a practical consideration you're not thinking of. If you had ever used punch cards and paper tape, you'd know: Punch cards can be dropped, ...
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  • 4,134
36 votes
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Why did mainframes have big conspicuous power-off buttons?

Yes, huge safety concerns as I remember engineers sitting inside the cabinets of large mainframes while it was running, fully powered, large currents in each cabinet powering fans. Cooling water being ...
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35 votes
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Were any IBM mainframes ever run multiuser?

Yes. There were CP/CMS and VM/370 - true multiuser operating systems running on the mainframe with individual users logged in. AFAIK it was mainly used for software developers (to develop IBM ...
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  • 4,134
31 votes

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

Uppercase text only needs six bits per character. The fundamental mistake that you are making is assuming that punch codes were binary numbers. They were not. The encodings were patterns, ...
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  • 1,821
31 votes

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

Although you have many correct answers describing the nature of the coding used in punched cards, no one has touched on the mechanical properties of the cards. Regular users of punched cards in the ...
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30 votes

How big is a mainframe?

But I can't seem to find any pictures of a computer filling an entire room, much less a whole multi-story building. (Image taken form Centre for Computing History) Well, for example look at this ...
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  • 173k
29 votes
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What is a good COBOL specification to target when aiming to support ~75% or more of mainframe and minicomputer software bases?

[Preface: While the basic question may seem to be off-topic, as it's about today's use of COBOL, I like to see it as asking in help to educate about COBOL. The noble effort to keep the language alive ...
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  • 173k
28 votes
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What date is 74029 on an IBM Mainframe?

TL;DR: DATE=74029 reads as: Year (19)74, Day 029 (Jan 29th), It's an Ordinal Date in truncated form, expressed in terms of 2 digit year and 3 digit day of the year. Does anyone know when was it ...
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  • 173k
26 votes

What accounted for the cost of ENIAC?

So what was the other $478,000 spent on? Paying people to design and build it would have been a fairly big component. People often underestimate the cost of labour, particularly if it is their own ...
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  • 10.2k
24 votes
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What accounted for the cost of ENIAC?

One of the biggest factors is that when you have a machine that requires 5,000,000 successful solder joints to function properly, you need to make sure that all of your solder joints are really really ...
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22 votes

How big is a mainframe?

Here's a picture of the "Strela" (arrow) computer (1954) Vacuum tubes, 2000 op/sec (on 43-bit fixed point), 150kWt, 300 m³
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22 votes
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What was the last non-monolithic CPU to come to market?

The world of large computers is amazing. MCM systems of monstrous in the eyes of a PC user parameters were widely popular right up to the cloud revolution, and even now, taking into account legal ...
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21 votes

How big is a mainframe?

The excellent history book "AN/FSQ-7: the computer that shaped the Cold War" describes the size of a 1950's era radar monitoring air defence computer. A single installation (a single computer) was ...
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  • 311
21 votes

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

Longer words mean more bits can be processed at once. An 8 bit processor can perform a 32 bit calculation, but it has to do it in 4 stages of 8 bits each. A 32 bit processor can do it in one stage. ...
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  • 14k
21 votes

Were any IBM mainframes ever run multiuser?

IBM mainframes are still around (IBM Z). Linux has been available for IBM Z hardware and its predecessor, System/390, for 20 years, and z/OS is itself a certified UNIX through the z/OS UNIX System ...
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  • 7,854
20 votes
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What was the most critical supporting software for COBOL on IBM mainframes?

TL;DR: Which components or facilities were the biggest obstacle to porting typical COBOL applications? Simply that there were not many applications that made sense to be ported to (desktop) micros. ...
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  • 173k
19 votes
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How was the C language ported to architectures with non-power-of-2 word sizes?

There is some code left over in the pcc codebase showing how the GCOS compiler (for the Honeywell/GE 6000 series) worked, it used 9-bit (ASCII, most likely) characters natively, but supported 6-bit ...
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  • 476
19 votes

Were any IBM mainframes ever run multiuser?

Another one to mention is MTS which was first released in 1967, last release in 1988. It was in use at Rensselaer Polytechnic Institute from 1976 to 1999, of which I took part during the early 80s. In ...
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18 votes

How big is a mainframe?

The main computer hall of the company I worked for in the 1970s and 1980s was about half the size of a soccer pitch - about 200 feet by 150 feet. That contained three IBM S/370 mainframes at one end, ...
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  • 6,385
18 votes
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What is the purpose of the yellow wired panels on the IBM 360 Model 20?

What is the purpose of the yellow wired panels It's the backplane, simply the wiring of the machine. on the IBM 360 Model 20? Not just there, but next to every mainframe was made that way. ...
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