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Questions tagged [ibm-pc]

For questions about the early IBM PC, clones and compatible systems.

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5 votes
0 answers
246 views

What's the Norton SI of my new PC? [closed]

In the field, the benchmark I used everywhere was the Norton Utilities Sysinfo Benchmark. It measured computer power in units of IBM PC horsepower. So the 8088 PC got an SI of 1. The AT had an SI of ...
23 votes
6 answers
4k views

How can I reverse-engineer the game Wizardry (1981) for PC, based on UCSD Pascal?

I am looking at the files included with the 1981 game Wizardry. The particular version I have is from a 1998 re-release, but I do not know if the binary is still the original 1981 release. My ...
30 votes
2 answers
12k views

Looking for PC graphics demo software from the early 90s called "Unreal"

Back in the early 90's I remember downloading a graphics demo called, I think, "Unreal". This was on DOS on a standard PC and probably downloaded from a BBS. Identifying information: It ran for ...
2 votes
0 answers
253 views

What is this PSU connector? Compaq Portable motherboard

I've lost the PSU wiring harness to my Compaq Portable motherboard in a move and I'm trying to figure out what connector this is. Here's a picture with some AT-era Molex connectors for perspective. ...
11 votes
1 answer
382 views

What's the earliest source for the legend of Gary Kildall's airplane snub?

A commonly repeated (and commonly debunked) legend describes how Gary Kildall blew his chance at writing the operating system for the IBM PC. Examples include the following: …legend has it that ...
26 votes
5 answers
39k views

How to use ISA card in modern PC

(Posted this on HW Rec but got no responses.) Would like to use an ISA expansion card in a modern PC. There are Expensive PCI - ISA adapters (but I cannot find any actually for sale now) USB-ISA ...
16 votes
5 answers
4k views

How is it possible to connect more than two floppy drives to a PC-compatible?

I've seen a few computers with more than two floppy drives, most with two 3.5" and one 5.25". My question is how was this achieved? I've heard that it could be done with a second controller card, but ...
21 votes
7 answers
8k views

Are there any good, non-abandoned PC emulators?

Mission: I'm trying to simulate a classic ~286/386/486/Pentium inside my modern PC (running Windows 10) in the most authentic way possible. Just a quick note to say that I (Sarah Walker) have decided ...
45 votes
2 answers
10k views

Why were some early PC 3D cards unsuitable for 2D graphics?

Some of the early PC 3D graphics cards such as the 3dfx Voodoo Graphics cards had a passthrough port to enable them to switch to a secondary card to display 2D graphics. I am curious to know why these ...
9 votes
2 answers
3k views

Can someone explain the logic behind Pause and Print Screen modifiers?

Firstly, do I have a correct understanding of what these keys do? On the Wikipedia SysRq page, it says that the Alt key must be held down to invoke SysRq. On the BIOS interrupt call page, it says ...
10 votes
1 answer
383 views

Were there Any Applications Making Explicit Use of the MDA's Colour Capabilities?

The first series of MDA adaptors for the IBM PC had the ability to show colours according to the attribute byte, much like the CGA does in text mode, but I don't remember any PC application that ...
6 votes
2 answers
526 views

What was the purpose of the “key” pin of the P8 connector of the IBM PC PSU, and why was it changed to +5V with the AT?

According to the IBM PC/XT Technical Reference page 3-6, pin 2 of plug P8 is a "key." (Note that this is the pin specifically; this is separate from the keying of the shroud, which is ...
4 votes
2 answers
316 views

ISA Extension cards using more than 64kB

Related to my previous question around VGA framebuffer being limited to 64kB I started to wonder if there was any extension cards (or similar) using more than 64kB of address space in linear fashion, ...
10 votes
5 answers
6k views

When did the PC bus start slowing access to video RAM?

The PC architecture, from the original IBM PC onward, has always been designed around the idea that video memory will be on an expansion card. This was an unusual design decision; most 80s computers ...
25 votes
5 answers
7k views

What were wait-states, and why was it only an issue for PCs?

PC compatibles in the 1980s were often advertised as having zero, one, two, or sometimes more "wait states". Zero wait states was the best. Basically, the wait-states I am asking about are due to the ...
5 votes
1 answer
317 views

Documentation for the SALUT preprocessor of the IBM Macro Assembler 2.0

The IBM Macro Assembler 2.0 included the SALUT program, which was a preprocessor for assembly language for structured programming. It was also included in the IBM Macro Assembler/2. I am looking for ...
33 votes
3 answers
3k views

How was the 80186 incompatible with the IBM PC?

Wikipedia's Intel 80186 entrymentions The 80186 would have been a natural successor to the 8086 in personal computers. However, because its integrated hardware was incompatible with the hardware used ...
20 votes
6 answers
13k views

Why didn't PC games eschew MS-DOS and deal with BIOS directly?

Given the memory referencing limits of MS-DOS for compatibility purposes, why didn't games produced for the 286+ processors eschew MS-DOS and talk directly with the BIOS or IO hardware, instead of all ...
19 votes
3 answers
3k views

How did DoubleDOS work?

Back in the MS-DOS days, there was a program DoubleDOS that you could run that would split your machine in half and multitask two separate DOS programs. While it didn't particularly work well for ...
7 votes
1 answer
473 views

How to treat an old PC

I have an old IBM PS/2 30/286, now sitting for a while on one of my desks. I'm a bit afraid that it will stop working sooner or later, so what's the best way to keep it 'alive' ? I fire it up every ...
8 votes
1 answer
603 views

Can you name this 386/486 era computer case?

Escort Computer is a Local PC brand in Turkey. They had popular Escort Multimedia series in late 90's. Prominent with distinctive case design. They were using off the shelf OEM hardware. I believe, ...
7 votes
3 answers
1k views

Were there any PCs where you could switch Turbo Mode via the keyboard?

All the PCs I have personally used or encountered which had a "Turbo Mode" (clock frequency switch, with frequencies in the 5-25MHz range) did this via a hardware button similar to the reset ...
62 votes
7 answers
11k views

Why did some old MS-DOS games lack the ability to exit them?

While playing around in DOSBox-X, I'm reminded of some DOS games which appear to entirely lack the ability to exit/quit/close them. One prime example of that is "Paratrooper" from 1982. I've ...
62 votes
7 answers
19k 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?
37 votes
4 answers
8k views

Why were those colors chosen to be the default palette for 256-color VGA?

Although subjective, I believe I'm not the only one considering default VGA 256 color palette to be hideous and ugly. What is the story behind this, why were these particular colors chosen?
7 votes
2 answers
586 views

Were VGA palette's HSV math properties used in practice?

In "Why were those colors chosen to be the default palette for 256-color VGA?", we've established that 216 of its colors represent a 24x3x3 truncated HSV color space. This results in an ...
7 votes
5 answers
2k views

Was there a notable mainstream 640×480 monochrome display for PC earlier than MCGA

On IBM PC compatibles, the first widely-known display subsystems capable of displaying 640×480 pixels (resulting in square pixels with a 4:3 display) were the MCGA and VGA in 1987. By then, 640×400 ...
8 votes
1 answer
427 views

Why weren't CGA colors selectable from palette?

Most memorable graphics mode in games for CGA was 320x200 which supported 4 colors. (I know there was 16 color composite mode trick, but let's ignore that.) Those 4 colors could be selected from ...
32 votes
5 answers
5k views

Does every retrocomputer and console with NTSC composite output have 'artifact color' ability?

Artifact color is heavily associated with the Apple ][, since that is the only method the machine had to produce a color display. I was looking at the fantastic demo for IBM PC + CGA, 8088MPH, and I ...
6 votes
1 answer
538 views

Have I Screwed the CMOS by Booting With the Clear Jumper Set?

I've been playing around with one of my old PCs recently, an IBM PC 340, and at some stage in trying to get a compact flash adapter to play nice I hit a weird issue where the system BIOS (a Surepath ...
9 votes
2 answers
3k views

How to determine BIOS-provided (INT 13h) hard disk geometry, and how to fix the MBR partition table to agree with it?

When transferring a hard drive from one computer to another, sometimes a situation can occur where the BIOS-provided CHS hard disk geometry (interrupt 13h without extensions) is different from the CHS ...
8 votes
4 answers
780 views

Who produced all-in-one / wedge style IBM compatibles?

The RetroManCave YouTube channel recently made me aware of the Sinclair PC-200 / Amstrad PC-20 and I already knew about the Tandy 1000EX / 1000HX but were there any other IBM-compatibles (or mostly ...
13 votes
4 answers
4k views

What actions, besides a hard power-off, did a blank screen with a blinking cursor allow?

I remember that, in the old days, a serious boot error could manifest in a screen like the above. (I have no idea if this may still happen. I haven't seen it for years, so I assume it is legacy as of ...
16 votes
3 answers
3k views

Who were the first engineers to "cleanroom" the IBM PC BIOS?

In the first season of the AMC show Halt & Catch Fire, the protagonist "Cameron Howe" is introduced. Cameron portrays a rookie engineer who is recruited for being extraordinarily talented, and is ...
6 votes
6 answers
2k views

When was the end of the floppy-only IBM PC clone?

Can we pinpoint in what year the number of IBM-compatible PCs (whether original IBM machines or clones) sold without a hard disk drive became so negligible that almost all new commercial software, ...
4 votes
1 answer
540 views

How do you find the EBDA address?

Normally, the "Extended BIOS Data Area" (EBDA) is located at the segment stored at 0x0040:0x000E, but this is only true for EISA and MCA systems (at least that's what I found in various ...
23 votes
2 answers
4k views

Were there any PCs using the i376?

The Intel 80376 was an x86 CPU that didn't support Real Mode or paging. It was targeted for embedded applications and it wasn't very successful at that (the 80386EX overtook it). Under these ...
9 votes
4 answers
2k views

Detecting if a video mode is supported by INT 0x10

The PC BIOS uses the INT 0x10, AH=0x00 function to change the video mode. There's a big list of video modes available, but how can I be sure that the video mode I want to set is supported? For example,...
6 votes
1 answer
631 views

AMD Interwave audio fx

I hope it's retro enough. Does anyone have any info on how AMD Interwave did sound effects? I'm mostly interested in reverb, but others would be nice to know about as well. The question is ...
12 votes
2 answers
1k views

Floppy drive detection on an IBM PC 5150 by PC/MS-DOS

The only functions of INT 13h available for pre-XT systems are the first six, from AH=00 to AH=05 (see here and here) Since function AH=08 (Get current drive parameters) is unavailable, how does PC-...
18 votes
5 answers
3k views

What is the most accurate way to map 6-bit VGA palette to 8-bit?

AFAIK VGA mode 13h palette has only 64 possible colors (6-bit) per channel. One obvious way to map those 64 colors to 256 colors is to multiply them by 4 (since 4 * 64 = 256): 8_bit = 6_bit * 4; This ...
4 votes
1 answer
534 views

How to use thinkpad x230 with PCjr 4863 monitor?

I understand it is probably more trouble than it is worth, but I am keen on using my 4863 IBM monitor as a second display for my x230. So far I've looked into converting its VGA signal to a CGA output,...
4 votes
3 answers
361 views

Were there clones and/or national variants of IBM's 84-key AT keyboard?

The 84-Key IBM AT keyboard (the one with a visibly separated numbers block but without dedicated cursor keys, with ESC and a dedicated SysRq key in the numbers block) seems to be the rarest of the old ...
14 votes
1 answer
2k views

Beep command with letters for notes (IBM AT + DOS circa 1984)

I'm looking for a reference for a command which used letters for musical notes, and would play very simple tunes with square waves. It ran on an IBM AT, circa 1984, which was running a version of IBM/...
16 votes
4 answers
2k views

Is it possible to detect a CGA card on an IBM PC 5150 by write/reading the Motorola 6845?

I am trying to programatically detect the CGA card on old IBM 5150-ish PCs. The Paku Paku game source code doesn't directly detect it. The strategy is to detect VGA, EGA, Tandy, PCJr, etc etc, then if ...
21 votes
4 answers
2k views

Did the IBM PC use the 8088's NMI line?

As I understand it, the Intel 8088 CPU used in the original IBM PC had two interrupt lines: INTR and NMI. INTR was fed from the Intel 8259 Programmable Interrupt Controller, which handled the IRQs ...
24 votes
16 answers
6k views

What were the most popular text editors for MS-DOS in the 1980s? [closed]

Since versions 1-5 of MS-DOS only came with the Edlin line-based editor, but were released on the IBM PC and compatibles, which had screen-based user I/O, my feeling is that most users wouldn't have ...
14 votes
3 answers
3k views

Help porting nasm code down from 386 to 8088 (shifts by more than 1 bit)

I have been writing some small asm COM program using Netwide Assembler (nasm), but am having trouble getting it to run on 8088 emulators like PCjs. I could use some help translating the assembly "...
26 votes
3 answers
4k views

What did Ctrl+NumLock do?

In my answer here I infer that the unusual scancode for the Pause/Break key emulates the user pressing and then releasing CtrlNumLock. Obviously that key combination did something specific, back when ...
16 votes
2 answers
952 views

What was special about "Vulcan" - the CP/M database program?

The Vulcan DBMS for CP/M micros was originally developed in 8080 assembly language by a contractor working for Jet Propulsion Lab, based on an earlier JPL mainframe program. This code went on to be ...

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