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1500 questions
26
votes
5 answers
Twist in floppy disk cable - hack or intended design?
There are many documents (e.g. this) describing the twist on two-drive floppy disk cable on IBM PC compatibles. While this is not the most proud example of clean hardware design, how much of this was originally planned in advance, or was it just…
tuomas
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26
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3 answers
Why was "C:" chosen for the first hard drive partition?
I was reading this answer, as the question came to my mind: why does C: indicate the first hard drive partition?
The usage dates back to CP/M (as noted in a comment), was embraced by MS-DOS, and persists in Windows 10.
I looked around but could not…
wizclown
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26
votes
7 answers
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 operation – but their heyday is long past. The same…
rwallace
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26
votes
8 answers
Why did 8-bit Basic use 40-bit floating point?
Nowadays floating point is usually either 32 or 64 bits, sometimes 16, occasionally 128. But of course, the Basic interpreters on the 8-bit machines, having to implement floating point in software anyway, on CPUs that did things 8 or at most 16 bits…
rwallace
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26
votes
6 answers
Why are old CPUs like MOS Technology 6502 and Motorola 68000 considered better for real time systems applications than modern x86 based CPUs?
Reading the Wikipedia article about real-time computing, I found written that:
Once when the MOS Technology 6502 (used in the Commodore 64 and Apple II), and later when the Motorola 68000 (used in the Macintosh, Atari ST, and Commodore Amiga) were…
bobeff
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26
votes
3 answers
Why does DOS ask for the current date and time upon booting?
In most versions of DOS, when they are started from a medium that lacks an AUTOEXEC.BAT file, the very first thing COMMAND.COM does is ask the user to confirm the current date and time:
Starting PC DOS...
Current date is Thu 10-01-2020
Enter new…
user3840170
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26
votes
6 answers
Why did Pokémon Red have so many overflow bugs?
(This question also applies to other Game Boy games, but Pokémon seems to be one of the best-documented.)
Pokémon Red & Blue (Red & Green in Japan) is a pair of Game Boy games about capturing "Pocket Monsters", or "Pokémon", by fighting them with…
wizzwizz4
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26
votes
4 answers
What register size did early computers use?
Prompted by this question querying the prevalence of byte-addressable memory on machines with 32 bit registers: Why is every address in a micro-controller only 8 bits in size?
I'm familiar with the concept that the mass-market microprocessors from…
Sean Houlihane
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26
votes
8 answers
Did any computer use a 7-bit byte?
In an answer to Why did IBM System 360 have byte addressable RAM I wrote regarding the choice of byte size:
7 bits would be a perfect match for ASCII, but engineers would instinctively recoil from basing the word sizes on a prime number.
(Okay,…
rwallace
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26
votes
4 answers
What's the terminal/home computer used as a prop in the computer school in Superman 3?
The DenOfGeek article [Brew2013] has screen captures from the movie Superman III, in particular the early scenes in the movie where character Gus Gorman is at computer programming school.
The terminal used appears to be a real terminal, attached to…
JdeBP
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26
votes
7 answers
Why were "data modems" so much more expensive compared to "fax modems" back in the day?
In 1997, my uncle visited and gave me a "fax modem" which he installed on our 486 PC and then managed to transfer over a fax document from a real fax in his home to our computer, running Windows 3.1. My eyes were as big as saucers: this was the…
B. Yath
26
votes
3 answers
What were the HW specifications for the actual PC speakers, before they were replaced by buzzers?
Back in the early 2000s, I remember that, what were at the time older, PC cases had actual loudspeaker instead of the buzzer, which was popular as the PC speaker on the PC cases of the time period.
I'm interested in finding out the actual technical…
AndrejaKo
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26
votes
10 answers
Why did the original design of COM on Windows rely on the Registry?
In the early 1990s Microsoft introduced COM (Component Object Model) which was widely used in various programming environments including Visual Basic 5 & 6. Also known as ActiveX (or at least if COM & ActiveX are not the same thing they are often…
StayOnTarget
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26
votes
3 answers
What do the '80/40' and 'keyboard' buttons on my Apple IIc do?
Above the keyboard of my Apple IIc there are two buttons that say "80/40" and "Keyboard".
On my machine, they both kinda feel broken. When I press them, they recede into the case and remain there for a while. Eventually they reset to their original…
Woodrow Barlow
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26
votes
6 answers
Was Unix ever a single-user OS?
I've been told that Unix started out as a Phone Switch OS and was not a multi-user OS at some time in its infancy.
As I'm always willing to learn new things, are there any greybeards around here older than me that remember this?
Bonus points if you…
Fabby
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