181 votes
Accepted

It's now safe to turn off your computer

TL;DR: it took a long time (on PCs) because the industry wasn’t ready to push it. Scroll down to “Why did it take so long?” for details. Shutdown screens That screen comes from Windows 95 and its ...
Stephen Kitt's user avatar
92 votes
Accepted

How was early randomness generated?

The one-word answer to your question is "badly". The way to create random numbers quickly is via a Pseudorandom number generator (PRNG). That Wikipedia page gives the history of PRNGs and in ...
pndc's user avatar
  • 11.3k
83 votes

How was early randomness generated?

Anyone who considers arithmetical methods of producing random digits is, of course, in a state of sin — John von Neumann The method that RAND used to calculate their A Million Random Digits with 100,...
scruss's user avatar
  • 21.6k
81 votes
Accepted

What did the 'turbo' button actually do?

The Turbo button originally adjusted the clock speed of the computer between the full speed of the machine and a slower speed intended to be compatible with something more industry standard. It wasn't ...
mschaef's user avatar
  • 4,836
77 votes

Why does the 80486 take longer to execute simple instructions than complex ones?

TL;DR: It's the pipeline. The 80486 contains parallel operating stages for decoding, operand fetch, execution and write back. So while an ADD reg,reg does take 3 clocks to perform, as it did in the ...
Raffzahn's user avatar
  • 223k
74 votes
Accepted

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 ...
Brian Tompsett - 汤莱恩's user avatar
71 votes
Accepted

Reason for the Amiga clock speed

The architecture of most "color computers" of the 70s-80s was very tightly built around the NTSC color video standard. Almost all of them had a 14.31818 MHz crystal. Note that this is four times ...
Harper - Reinstate Monica's user avatar
66 votes
Accepted

Why were chips socketed in early computers?

Caveat: It might be useful to distinguish between high volume low cost computers (like the mentioned CoCo) and low volume high cost machines (like Intel boards - or workstations). I assume the ...
Raffzahn's user avatar
  • 223k
63 votes

Why did computers use a power supply with a socket?

The socket (or rather inlet) is most definitely standard, it’s a IEC 60320 C14 inlet. The standard was published in 1970. C6 and C8 are commonly used for laptop power supplies and smaller audio ...
Stephen Kitt's user avatar
63 votes
Accepted

Was AGP only ever used for graphics cards?

I researched this question online fairly thoroughly a while back. I could not find any reference to an AGP device that wasn't a graphics card. It wasn't exhaustive, and absence of proof is not proof ...
RETRAC's user avatar
  • 13.7k
63 votes

What is this large device labelled 'Telefunken Datenspeicher' and how does it work?

It's a Demonstrator for an ALU and Memory. It's a serial ALU with registers, data path and a 6 byte storage, falling short to be a CPU. An ALU (German as well ALU, sometimes 'Rechenwerk') is a ...
Raffzahn's user avatar
  • 223k
62 votes

Why did early arcade games use vertical displays?

Having the display vertical reduces the width of the cabinet. This means that a game machine can be fitted into a smaller space in a pub/bar, or in an amusement arcade where machines are in rows you ...
Owain's user avatar
  • 679
60 votes
Accepted

Why do programmable sound generators like SID include a noise generator?

One basic distinction in acoustics is the one between sounds that oscillate with a pattern that is repeated over time and sounds that are chaotic in nature, and show no repetitive pattern. Sounds ...
Schmuddi's user avatar
  • 925
60 votes
Accepted

Why did trackballs disappear?

Why did trackballs disappear? To start with, they didn't. They are still around and can be bought in many variations. For example, Kensington sells six kinds of trackball, and Logitech sells three. ...
Raffzahn's user avatar
  • 223k
59 votes

Have programming languages driven hardware development?

Simply yes. And not just a few instructions, but whole CPUs have been developed with languages in mind. Most prominent maybe Intel's 8086. Already the basic CPU was designed to support the way high ...
Raffzahn's user avatar
  • 223k
56 votes

It's now safe to turn off your computer

Was it really that hard to implement a self shut-off? Yes. Yes it was. Until Windows 95, all power switches were that - a switch. On or off, nothing else, and there was no "self shut-off". Nor ...
Graham's user avatar
  • 2,064
55 votes
Accepted

What determines the color of every 8th pixel on the Apple II?

A nice one - and coming up every now or then. TL;DR The Apple IIs video logic produces a B&W bitstream at the right frequency to bedazzle an NTSC TV set in a way to make it 'see' colour. The ...
Raffzahn's user avatar
  • 223k
55 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 ...
hotpaw2's user avatar
  • 8,183
53 votes

Why did so many early microcomputers use the MOS 6502 and variants?

First, for Commodore's part, it should be obvious the reason for choosing the 6502 microprocessor for all their 8-bit machines (notwithstanding the dual-processor SuperPet and C128) - Commodore owned ...
Brian H's user avatar
  • 60.8k
53 votes
Accepted

Is it safe to turn on a 40-year old TRS-80?

It definitely does not hurt to open the case and have a look at the PCB. When opening, be especially careful with the keyboard ribbon cables - They are apparently known to become very brittle with age ...
tofro's user avatar
  • 35k
52 votes
Accepted

Have programming languages driven hardware development?

Interesting question with an interesting answer. First let me get one thing out of the way: One example from this answer mentions how C pointers were, at least in part, influenced by the design ...
JeremyP's user avatar
  • 11.8k
51 votes

Simplest system to create an emulator for

I'm putting CHIP-8 forward. This system is essentially a virtual machine developed for some reason. There are games written for the CHIP-8. It has a few opcodes, a stack, a couple of timers, and a ...
Omar and Lorraine's user avatar
50 votes
Accepted

Why did CPU designers in the 70s prioritize reducing pin count?

Existing Machinery. Reasoning about the usage of existing packages Adding a few hundred transistors for multiplexing is approximately free compared to buying production machinery for several millions -...
Raffzahn's user avatar
  • 223k
49 votes
Accepted

Why were optical drives not used as secondary storage instead of magnetic drives?

For the simple reason that until relatively recently, it was very difficult to make a rewritable optical medium, but it was easy to make a rewritable magnetic medium. Magnetic tape as a recording ...
Chromatix's user avatar
  • 16.8k
48 votes

Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?

After some more research, I believe I've stumbled across the real answer: The VIC-II and SID used a larger process node size because Commodore's fabrication line circa 1981 was uniquely positioned ...
supernoob5000's user avatar
48 votes
Accepted

Did any computer use a 7-bit byte?

The PDP-10 had 'byte instructions' that could process a sequence of bytes of size 1 to 36 bits. The byte pointer was a word containing an 18-bit word address (and the usual index/indirect indications)...
dave's user avatar
  • 35.6k
47 votes
Accepted

When did computers stop checking memory on boot?

When did computers stop checking memory on boot? Never. I remember my old 8088 used to do this (640K OK) but can't remember seeing anything like this since. Does this still happen and it's just ...
Raffzahn's user avatar
  • 223k
46 votes
Accepted

Why did the ZX80 CPU run at only 3.25 MHz?

TL;DR Because it needs the least chip count and thus makes it the cheapest. It's a Sinclair. Full Story: The Sinclair ZX80 used a Z80A running at 3.25 MHz. But this chip was rated for 4 MHz. Why was ...
Raffzahn's user avatar
  • 223k
46 votes
Accepted

Why was computer memory so expensive and scarce?

As noted in some initial comments (but I feel fine answering, as I had the exact same ideas when I read the question), this is a general progression of technology but there are two very specific ...
manassehkatz-Moving 2 Codidact's user avatar

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