Questions tagged [design-choices]

Justifications and trade-offs of historical hardware and software designs, and their possible alternatives.

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50
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. ...
107
votes
7answers
25k views

Why was `!` chosen for negation?

It seems that the use of the exclamation mark ! to denote negation started with the C programming language (as far as I can tell from my Google research). Nowhere though is mentioned who and why chose ...
72
votes
7answers
13k views

Why wasn't ASCII designed with a contiguous alphanumeric character order?

Anyone who has dealt with strings at a low level (e.g., writing a parser in C), knows that doing so tends to involve frequent checks of—either manually, or through isalpha(), isalnum(), etc—whether a ...
35
votes
5answers
10k views

Why is the clock frequency of the PS/2 keyboard protocol so high?

The PS/2 keyboard protocol allows the keyboard to generate a clock rate between 10 kHz and 16.7 kHz. At 11 bits per scancode, 10 kHz is a massive 909 scancodes per second. World-record holder Barbara ...
23
votes
8answers
5k views

Why not constant linear velocity floppies?

The outer tracks of a disk are longer than the inner tracks, and could therefore potentially hold more data. Constant angular velocity puts the same number of bits on every track, which wastes much of ...
19
votes
3answers
2k views

What was the role of Commodore-West Germany?

Most of the history of Commodore in personal computers took place while East and West Germany were divided, and Commodore maintained a significant corporate presence in West Germany. While I believe ...
16
votes
4answers
3k views

Why does Pascal have numeric labels?

Pascal was intended, in part, to be a simple language to implement. Some of the design decisions reflecting this are Declarations/definitions must be given in a strict order (labels, constants, types,...
5
votes
2answers
448 views

When was beeping invented, in a user interface sense?

UPDATE: thanks all, lots of good discussion but I think this question is a bit too vague to be answerable. I'm casting my own close vote against it and will re-ask a more specific one. Specifically I ...
15
votes
2answers
3k views

Why did some CPUs use two Read/Write lines, and others just one?

Many 8-bit processors, such as Motorola's 6800 and MOS Technology's 6502 make use of a single pin to indicate to the rest of the system whether the CPU wishes to read from or write to a memory ...
5
votes
0answers
232 views

What was the first device to "beep" in lieu of tactile feedback to button presses?

I'm splitting this question off of When was beeping invented, in a user interface sense? because I think it's more answerable on its own and I suspect likely to still be computing-related. At some ...
2
votes
0answers
327 views

Why did the Spectrum Next choose Z80 on FPGA? [closed]

I'm curious to understand why the Spectrum Next uses Z80 on an FPGA instead of something like at eZ80? I would have imagined they would choose the eZ80 since it is still a production part. Anyone ...