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62
votes
1answer
10k views

What's the story behind the name “X11”?

To this day on Linux configs and startup scripts for the GUI system are stored in /etc/X11. I remember this name appearing alone, or alongside others - XFree86, X.org, X - for as long as I had contact ...
61
votes
3answers
12k views

Why did DOS use dollar-terminated strings?

According to a few tutorials I am seeing, DOS used dollar-terminated strings to write to the terminal. This seems to also be documented here on INT 21H. AH = 09h - WRITE STRING TO STANDARD OUTPUT ...
61
votes
2answers
10k views

Why are a lot of monochrome computer monitors green?

In my perception, the most common color for monochrome computer monitors is green or white/grey, though I have seen orange monitors. Is this genuinely the case, and if so, is there a reason for it?
60
votes
10answers
8k views

What makes accurate emulation of old systems a difficult task?

Thanks to a lot of passionate and skilled people, we can emulate pretty much any retro platform today. For most people they perform well enough, but in fact, a substantial amount of these emulators ...
60
votes
2answers
19k views

What is the “two-drive trick” that can read Amiga disks on a PC?

Standard belief is that the floppy disk controllers used on PCs are incapable of reading Amiga floppy disks, due to the PC disk controller expecting a very specific low-level format of disks, whilst ...
60
votes
4answers
10k views

Why did F1 become the Help Key?

There was actually a pretty big push among some vendors in the 1980's to have a dedicated Help Key (conveniently labeled as Help). Atari introduced it in 1983, and kept it to the end. The Commodore ...
60
votes
1answer
4k views

How do I extract the program from the Radiohead “Nude” tribute by James Houston?

One of my favorite videos ever is a tribute to Radiohead "Nude" by James Houston. I have never seen the program in the video available to download, so I've just made an attempt to extract it myself. ...
59
votes
6answers
8k views

Reason for the Amiga clock speed

The Amiga used a CPU rated for 8 megahertz, but clocked at 7.14 megahertz. What was the reason for this number? I remember it was something to do with a multiple of the frequency of the video ...
58
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 ...
58
votes
5answers
16k views

Which Linux or BSD distributions do still support i386, i486 or i586 CPUs?

Unfortunately Debian kicked out Pentium 1 (i586) CPU support from its 32-bit PC port (named i386 for historic circumstances) for its next stable release Debian 9 Stretch. (Then again they complain ...
58
votes
1answer
11k views

When was the famous “sudo warning” introduced? Under what background? By whom?

On all Unix-like operating systems, sudo is often provided as the standard package for executing commands as superuser (or an alternative user). When sudo is invoked by the user for the first time, ...
57
votes
8answers
13k views

Could you reverse engineer silicon just by looking at it?

I was interested in a recent interview of Masayuki Uemura, one of the engineers who designed the Nintendo Famicom in the early 80s. During initial design phase of the Famicom, one of the first things ...
57
votes
3answers
14k views

Who set the 640K limit?

We all know that "640K should be enough for everyone". But who actually set this limit? The quote is often attributed to Bill Gates, but it doesn't seem like a decision for an Operating System vendor ...
57
votes
3answers
6k views

How does the LOADALL instruction on the 80286 work?

This undocumented instruction existed in the 80286 and, I believe, the 80386. I think it was added while debugging the chip, so the engineers could quickly put the processor into any state and test it ...
56
votes
19answers
17k views

Why were computer customers called “Users”?

The term User for computer hardware and software customers has been universal for as long as I can remember. It has always applied to both hardware and software customers - There were "Lotus Users" ...
56
votes
7answers
9k views

Why did the MS-DOS API choose software interrupts for its interface?

Access to the DOS API was done through the INT 21h x86 instruction. This was always counter-intuitive to me, coming from 8-bit systems that accessed system services by calling subroutines through a ...
56
votes
6answers
17k views

What did the 'turbo' button actually do?

I remember the computer I played Commander Keen on as a child had a turbo button that I was forbidden to touch, what did this button actually do?
56
votes
2answers
5k views

Why was the return key symbol ⏎ drawn differently from the motion of a CR-LF?

In the operating system (DOS) of IBM PCs, newlines were represented by a carriage return (CR) character, followed by a line feed (LF) character. The motion of a printer or teletype receiving such a ...
55
votes
8answers
9k views

How were Western computer chips reverse-engineered in USSR?

The British ZX Spectrum computer had many clones in the Eastern Bloc. It seems many of them were built using Russian-made chips from the Angstrem factory in Zelenograd in/near Moscow. The Russian ...
55
votes
6answers
13k views

How did old MS-DOS games utilize various graphic cards?

Nowadays each graphic card has some driver in operating system that translates some (typically) standard API such as OpenGL, so that programmers use some standardized API code to tell graphics cards ...
54
votes
7answers
12k views

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, ...
54
votes
8answers
9k views

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 ...
54
votes
6answers
16k views

Why do old games use flashing as means of showing damage?

When you play old games, especially platformers, a common "special effect" is rapid blinking of your character when they are hit. Also, enemies often blinked before dying. Not all games did this, but ...
54
votes
8answers
9k views

Could we have avoided the whole UTF-16 fiasco? [closed]

Anyone who has studied Unicode and is honest will admit that UTF-16 was kind of a mistake. It was born from the early assumption that 16 bits would be enough for all of Unicode. Then a hack was ...
54
votes
3answers
11k views

On DOS computers, what would the PARK command do?

In 1994 or so, we had an old computer at my primary school. I remember finding out that it had a park command. From reading its documentation, it said that this command should be executed prior to ...
54
votes
7answers
7k views

Are there any modern compilers that can generate Amiga/m68k executables?

I would quite like to resurrect my openkick project. As I note on that project's README.md, it is stalled because GNU GCC is not fit for purpose. Sadly, there do not seem to be any other modern ...
53
votes
8answers
11k views

What was the rationale behind 36 bit computer architectures?

Was there some particular design theory or constraint that made a 36 bit word size attractive for early computers? As opposed to the various power-of-2 word sizes which seem to have won out?
53
votes
11answers
15k views

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, ...
53
votes
4answers
14k views

Why were most PCs and electronics beige back in the day?

Back in the day (especially during the 70's and 80's), it seems that most computers and electronics were colored 'beige'. It seems it would be easy to use different colors, so why didn't they? Some ...
53
votes
2answers
11k views

Why did Commodore fill their power supplies with epoxy?

If you know anything about the Commodore 64 (and other Commodores, really) you know that Commodore really went the cheap route and produced some awful power supplies. The Commodore 128 PSU isn't ...
52
votes
12answers
12k views

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 ...
52
votes
8answers
18k views

How long will floppy disks maintain data integrity?

This was on CNN today: The U.S. is still using floppy disks to run its nuclear program Which led me to read through this article: Think the floppy disk is dead? Think again! Here’s why it still ...
51
votes
17answers
14k views

Simplest system to create an emulator for

Next year I'm going to teach a 2-semester microprocessors class to third-year undergraduate EE students. In order to sign up for the class, students need to have completed programming and digital ...
51
votes
12answers
11k views

What early home computers have more than one CPU, where both could be used by the programmer? [closed]

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 ...
51
votes
4answers
11k views

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 ...
51
votes
3answers
12k views

What was Nintendo's Software Development Environment for NES Games?

(This question was inspired by my previous question What kind of software was used to develop Nintendo 64 titles?) The NES used a modified 6502 processor and most games were written in Assembly. ...
51
votes
1answer
6k views

How was collision detection done on the Asteroids arcade game?

In honor of today's landing of and sample collection by the OSIRIS-REx spacecraft on the asteroid Bennu: How did the arcade game Asteroids detect collisions between the screen objects (player's ship, ...
50
votes
14answers
11k views

Did many programs really store years as two characters (Y2K bug)?

The claim that programs stored dates as two ASCII or similar characters because computers were limited in resources seems wrong to me because it takes more memory than one 8-bit integer would. Also in ...
50
votes
4answers
7k views

What should we do with manuals from the 80s?

I have access to several meters of manuals of various sorts around CP/M on PCs and various bits on mainframes. These are earmarked to go after decades of "cannot dump that" heartbleed. Most are ...
50
votes
10answers
9k views

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 ...
49
votes
8answers
13k views

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 ...
49
votes
8answers
10k views

Why didn't the 8086 use linear addressing?

The 8086 used a segmented memory architecture where the linear address was computed from a 16-bit segment number and a 16-bit offset. This greatly complicated things from a programming perspective. ...
49
votes
2answers
7k views

How was the blinking terminal cursor invented?

I was just staring at my blinking terminal cursor: And was wondering where it comes from. Does anybody have some piece of history about the blinking cursor? I couldn't find much online. E.g.: when/...
49
votes
4answers
3k views

What precautions to take when powering on old computer for the first time in years

I have a Commodore 128D that hasn't been powered in about 15 years. I want to begin using it again. It has been stored in cool dry places like attached garages, in a cardboard box. I hope this ...
48
votes
20answers
13k views

Did personal computers ever support 8" floppies?

When I look at the following picture, it seems a bit awkward to me that personal computers ever supported 8" floppies (unless the size of your computer case was as big as a fridge !): Am I right or ...
48
votes
9answers
19k views

Why were floppy drives not any faster?

180rpm to 360 rpm, unlike 12000rpm on optical discs, was how fast floppy disks got. I am not sure, whether all drives had the same speed, but 360rpm is not close to the physical stress limitations of ...
48
votes
3answers
7k views

Strange math syntax in old basic listing

I'm browsing through an old book "Basic Computer Simulation" from 1983. It contains a line of BASIC code that reads: LET Z1 = M * D1 * (PQ / A) [ 3 I understand all of the code except the "[ 3" I ...
48
votes
4answers
10k views

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 ...
48
votes
6answers
7k views

Can a PET 2001 be physically damaged from BASIC?

In the early 1980s my primary school was the proud owner of a Commodore PET 2001. There was a commonly held belief among the young geek fraternity that there existed a BASIC command—perhaps a ...
48
votes
4answers
15k views

What causes that “organic fade to black” effect in classic video games?

This happens a lot on older consoles than this, but for this specific example, I'm picking what I spotted today: Harvest Moon for PlayStation. Here is a screenshot of the player just about to exit an ...

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