Questions tagged [ibm-pc]
For questions about the early IBM PC, clones and compatible systems.
294 questions
5 votes
2 answers
646 views
How does the capacitive sensing works on the PC / PC/XT keyboard type 2?
I am trying to replicate the IBM System/23 Datamaster keyboard using off-the shelf components. This means that I am using a 8749 instead of the 8048 and some 7400s to replace the LST/MST. For your ...
- 2,298
9 votes
2 answers
2k views
Where did the baby AT motherboard format come from?
This recent video on LPX claims the baby AT motherboard appeared overnight without any explanation. Magazines didn't mention it in 1986 and in 1987 they referred to it as if you already knew what it ...
- 1,342
6 votes
2 answers
766 views
Is MDA based on the Datamaster video subsystem?
I have read the claim (Byte Magazine, September 1990, "The creation of the IBM PC") that the IBM PC Monochrome Display Adapter (MDA) is based on the previous computer's video subsystem, ...
- 2,298
16 votes
1 answer
2k views
How Did 1988 PCs Achieve 12 MHz DRAM Cycles with 80 ns Chips
I'm haunted by an advertisement (on p.47 in the August 1988 issue of BYTE) for a zero wait state 12 MHz 80286 PC with 80 ns memory. How was this possible given the timing constraints of chips of the ...
- 1,598
17 votes
7 answers
4k views
How did PC games reproduce PCM sounds on PC speakers using PWM when speakers had poor frequency response?
The method I am referring to is visible in videos such as these: https://www.youtube.com/watch?v=Wu5zd5fCaPA https://youtu.be/fWDxdoRTZPc?si=cqPRdGtLAR_uAfK7&t=509 The PC speaker from what I ...
- 1,067
4 votes
0 answers
316 views
What AT clones supported XT keyboards?
Recently, I was researching IBM PC keyboards and their compatibility. I found out that there are a lot of misconceptions online about them. First, there are two keyboard protocols that are not ...
- 902
8 votes
2 answers
416 views
Are there keyboards with XT/AT autodetect? How is it implemented?
Nowadays, it's common for keyboards to automatically switch to either PS/2 or USB mode depending on the port the keyboard is connected to. This way the keyboard can have either connector and use the ...
- 902
11 votes
3 answers
2k views
Lowest possible chip count of an XT-class IBM PC compatible computer
The original IBM PC had a very large PCB with a lot of components, but over time various clones of this design simplified it and lowered both the area of the board and the number of components on it. ...
- 902