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54
votes
11 answers
Why not use fractions instead of floating point?
Considering all those early home computers, the ZX Spectrum, the Galaksija, the VIC-20, the Apple I/II/III, and all of those, they all have some 8-bit CPU which does integer arithmetic and no floating point. So these machines have some kind of…
Omar and Lorraine
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54
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5 answers
Why did C have the return type before function names?
In general, there are two types of syntax of defining functions - Something like C, C++, C#, or Java (int functionName(char arg)) vs the ML (and others) tradition of defining the return type after the function (and using something like a fun keyword…
Unix
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54
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8 answers
Why didn't early single-chip CPUs support multiplication instructions
Early single-chip silicon CPUs like the Zilog Z80 or MOS 6502 did not have a multiply instruction at all. Was this because the technology did not exist at the time to implement it, was it too expensive or was there simply no need for such an…
Bartek Malysz
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54
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Did the Apollo Guidance Computer really use 60% of the world's ICs in 1963?
This NASA webpage makes this claim about the Apollo Guidance Computer:
By 1963, MIT - during the testing and development of the AGC Block I units - had ordered and consumed some 60% of the then world's available IC's !
Is this claim plausible --…
DrSheldon
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53
votes
11 answers
Why did trackballs disappear?
For a desktop computer, a mouse is a great pointing device. For a laptop if you don't want an extra device to keep track of, you need an alternative. The options I'm aware of:
NubLow-tech, cheap, compact and reliable, but miserably imprecise. Did…
rwallace
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53
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10 answers
Why was preemptive multitasking so slow in coming to consumer OS's?
Preemptive (rather than cooperative) multitasking was a highly-touted feature for PC's in 1996, with its inclusion in Windows 95 for the first time. It was also highly-touted for 2001 Macs when included with OS X. Earlier versions of both these…
Brian H
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53
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7 answers
Why use static RAM addresses instead of the stack?
I'm studying the 65c816 assembly for the 1994 game, Super Metroid.
A hobbyist studied the game in-depth and created a RAM map. From it:
7E:0B56 - 7E:0B57 Moves Samus this distance horizontally, in subpixels.
7E:0B58 - 7E:0B59 Moves Samus this…
Andrew Cheong
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53
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12 answers
How was the first assembler for a new home computer platform written?
How did the 8-bit computers (Spectrum, Commodore, Atari, Amstrad etc) typically "bootstrap" from bare electronics into a platform with a working assembly language and OS?
What I mean: An assembler is not an application exactly trivial to write.…
SF.
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53
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7 answers
Why does the Commodore C128 perform poorly when running CP/M?
I have seen several claims of poor performance of the C128 when running CP/M, and would like to better understand these claims, especially in comparison to other CP/M machines of the early to mid-1980s.
The C128 has a Z80A microprocessor clocked at…
Brian H
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53
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8 answers
How is it possible that classic 3D video games such as Super Mario 64 and Ocarina of Time can contain such bizarre "glitches"?
I've been watching "speedrunners" play those games for quite some time. I still can't believe what my eyes are seeing. Somehow, they have managed to find bizarre bugs in the games which enable them to do things which I cannot imagine that I or…
Dewsnap
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52
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4 answers
Why did the IBM 650 use bi-quinary?
The IBM 650, announced in 1953, was the world's first mass-produced computer. It represented numbers in decimal, which is understandable, both because it needed to work with exact money amounts, and because converting from binary to decimal for…
rwallace
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52
votes
12 answers
What early home computers have more than one CPU, where both could be used by the programmer?
I am interested to know if any computers that are on-topic for this site had more than one CPU, where this plurality could be leveraged by a programmer.
Some cases I don't so much care about:
The Amigas could add a faster processor, but doing so…
Omar and Lorraine
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52
votes
2 answers
What is the origin of this bizarre advert of people wearing swimsuits in a room with computer hardware?
This image of people wearing swimsuits in a room with computer hardware popped up on Twitter recently.
Where was this advertisement published, and what computing product or service is it offering?
user
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52
votes
4 answers
What did the 8086 (and 8088) do upon encountering an illegal instruction?
Preface: This question does in part intersect with Use of undocumented opcodes, but targets especially the 8086 instruction handling.
I was reading Tanenbaum's "Operating Systems, Design and Implementation" 3rd edition (The MINIX Book), where I…
Joe D
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51
votes
16 answers
How was it back then in 1984, when the Apple II had color, and the new Macintosh didn't?
I imagine it being a huge downgrade for some, not to have color on the Macintosh. Macintosh games were black and white in the beginning, while Apple II had color.
I'm especially interested in experiences of people who lived through that time.
Johannes Bittner
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