Questions tagged [ibm-pc]
For questions about the early IBM PC, clones and compatible systems.
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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 ...
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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 ...
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Which font with slashed zero is being used in this screengrab?
Do you know which font is being used in the video here: https://www.youtube.com/watch?v=xnudvJbAgI0? A screengrab of the video that shows a lot of text:
We can see that the zeros are slashed, so it ...
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Why did some BIOSes have the timer tick wrap around at 1800B1h instead of at 1800B0h?
The 1989 2nd edition of the DOS PROGRAMMER'S REFERENCE says:
Midnight is determined as the number of ticks in a complete day of 86400 seconds (1573040 ticks of the clock, for a total elapsed time of ...
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What technical aspects make NEC PC-98 architecture incompatible with IBM PC architecture?
PC-98 was a series of x86-based Japanese computers that offers Kana-Kanji support, which shared some hardware similarities and operation systems with IBM PC, and software was relatively easy to port ...
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Were CD-ROM-based games able to "hide" audio tracks inside the "data track"?
I have been digitizing the audio tracks from various old CDs lately, because I have become a lossless audio snob who no longer is able to tolerate MP3s but need FLACs of everything. Many of these are ...
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Why did x86 support self-modifying code in the 80s and 90s?
In this question, by 'self-modifying code', I mean software that writes to a section of code that the CPU will very soon fetch and attempt to execute.
I am not here talking about the software ...
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How to write text in MODE 0x13?
I have read How to write directly to video memory using "debug.exe" in MS-DOS? and I know how to write text to video memory in mode 0x3 but I can't figure out how to write text to video ...
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Why was video, audio and picture compression the poorest when storage space was the costliest?
"Full-motion video" sequences in PC and console games in the 1990s were bad-looking, in spite of taking huge amounts of storage space. Same thing with random short video clips that I ...
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Why did IBM PC have horizontal cursor instead of vertical or block cursor?
Most 8 bit machines, like C-64, seem to have block cursors, while modern user interfaces often have vertical cursors. PC has horizontal cursor of two (or 3) scanlines by default, and block cursor for ...
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Was it possible to cause persistent changes to a mid-1980s IBM-PC using POKE in GWBASIC?
TL;DR: Using the DEF SEG and POKE commands in GWBASIC, was there any way to make changes to an IBM-PC compatible computer that would (a) persist even after a reboot and (b) cause an increase in crash ...
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IBM PC Alt + numpad for entering character codes: firmware, BIOS or OS?
Back in the days of MS-DOS, when I needed to type a special character that wasn't part of the keyboard layout, I would press down the left Alt key and type out the character code on the numeric keypad ...
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How did Joysticks with more than 4 buttons and all those extra features work on a Game Port?
The question is pretty straight forward. How did they do so much more than the simple, unidirectional 4 axis of analog control, plus 4 on/off buttons?
There was surprisingly precise force feedback ...
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What is this early 3D platformer?
Video: https://www.youtube.com/watch?v=8_-fcFivTS8&t=599s
Image:
I'm having a hard time tracking down a game I played when I was a kid. It was on DOS in the early 90s. It had flat-shaded polygon ...
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Chaining IRQs in x86 ROM code
Objective Summary: I need to write a sleep() function to be used in 8088 (PC/XT ISA) ROM code with 1 ms resolution. Though the question can be more generalized to chaining INTs with data in different ...
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Why does NumLock exist?
My keyboard has over a hundred keys on it. But there's one labelled NumLock. Pressing it turns the numeric keypad into a duplicate of the dedicated arrow keys just left of it. This doesn't seem useful ...
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What is a "sympathetic bit"?
I am reading about BIOS in Phil Storrs PC Hardware book: What happens when we turn on a PC ?
Next comes the incremental check of all the RAM memory. The RAM memory is written to, and read from, with ...
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How does the BIOS distinguish Interrupt(08h-12h) from INT instructions, vs. actual exceptions inside the CPU?
This is purely academic, out of date, out of curiosity. Let's go back to the 1990s, before Windows, when real-mode DOS programs were common.
The BIOS assigned INT 08H+ for their own interrupt handlers,...
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IBM/Xebec XT Fixed Disk Adapter "Custom" Drive Types
It's generally believed that the IBM/Xebec Fixed Disk adapters were hardware limited to only four different drive geometries - of which, only the last revision of the card was user configurable (...
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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 ...
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What information was "off limits" to IBM PC clone BIOS authors?
Back in the PC clone days the accepted legally defensible method of selling a non-IBM PC BIOS was using a "clean room" whereby an engineer who had never been exposed to proprietary IBM ...
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Did any PC software floating point use non-IEEE format?
During the 1980s, prior to the 486 (well, strictly speaking, prior to the discontinuing of the 486SX in the nineties), IBM PCs and compatibles had hardware floating point only in the form of an ...
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Who were the market for those "speed up your computer" shareware applications back in the day? [closed]
In the Swedish computer magazine PC Hemma ("Home PC") from February 1997 (p. 68), they included a floppy disk with shareware programs related to "trimming your PC", as well as a ...
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Meaning of KP_Begin and VK_CLEAR names of numpad 5
The key "5" at the standard keyboard numpad ("keypad" in XFree86) is named KP_Begin in XFree86 and VK_CLEAR in Windows virtual key space. What are these names originated in? Are ...
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Was there any software on the IBM PC that specifically took advantage of the NEC V20?
Back in the day I remember friends upgrading their IBM PCs (and compatibles) with a NEC V20 CPU. While this was mostly to get a bit more performance out of their machines over the stock Intel chip, I ...
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Cost of PC vs. Amiga 500 in Europe
Based on Commodore sales figures, and other historical claims, the Amiga achieved its peak popularity in 1990-91, with European sales being the leader. By 1990, with the rapid fall in PC clone prices, ...
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What was the first PC-compatible computer to have a DRAM controller?
The original IBM PC used a timer from the 8254 PIT and a channel from the 8237 DMAC in order to refresh RAM with dummy reads (and I think used NMI to signal parity errors.) I'd like to know when PC's ...
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What is 'Adaptive Tile Refresh' in the context of Commander Keen?
The question Did John Carmack really invent "Adaptive Tile Refresh"? asks about the origins of the scrolling and drawing techniques used to allow an MS-DOS PC to provide a NES console-like ...
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Did John Carmack really invent "Adaptive Tile Refresh"?
John Carmack is credited with making fast-paced arcade games like Commander Keen possible on an IBM-PC that had no specialized graphics controllers suited for those, thanks to the "Adaptive Tile ...
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What old LCD monitor am I thinking about?
I once had a PC with an LCD monitor and I'd like to remember what model that monitor was. Here's what I remember:
It was basically a beige rectangular box with right angles on all corners. Only the ...
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In x86 real mode, how does BIOS know what hardware is present?
I know that BIOS is obsolete, hence why I'm asking here :-) BIOS needed to do things like start loading the OS, for which it (usually?) would have needed things like a hard disk driver.
However, BIOS ...
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If a PS/2 device on a 32-bit x86 sends a byte to the IO port 0x60 and you read it, what happens next?
I'm writing a hobby OS and the first thing I want to do is access PS/2 devices (it's a somewhat legacy, 32 bit OS, so I figured it's relevant to ask here?).
I can see my PS/2 devices and I want to ...
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Why did the monsters have "infinite invisible pillars" of hitboxes vertically in all versions of the DOOM engine?
Even in the last version of the DOOM engine, v1.9, used for Final DOOM, there is this strange limitation in which all the monsters have an invisible, infinitely tall "pillar" above and ...
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Why did the BIOS load the MBR at 0x7c00?
The IVT is at 0x0000-0x03ff while the BDA is at 0x0400-0x04ff but boot sectors are loaded at 0x7c00. What was at 0x0500-0x7bff that caused this convention? I'm also curious why some MBRs relocate ...
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Why doesn’t my VGA-to-HDMI converter work with my 286 PC?
I have a Commodore PC 30-III with a Cirrus ISA VGA card in it.
I wanted to connect to an HDMI display by using a mini VGA-to-HDMI converter
The converter doesn't generate any output. The machine ...
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How was the real-time clock implemented in the original IBM PC and PC/XT?
I know that the IBM PC/AT added a battery backed real-time clock chip that independently maintained time whether the system was powered or not. I've also seen many of those big DS1287 clock chips on ...
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Why did PCs for the longest time have a default "memory test" on boot which caused them to take a long time to start? [duplicate]
Not just "really back in the day", but even as late as "only a few years ago" (meaning 15-20 years), every time I started my PC, it would slowly "count through" the ...
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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 ...
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What caused older computer fans to be so much louder than they are today?
I had one of those bulky IBM 486 PCs in the mid-1990s. Desktop form factor. I think it was probably made somewhere in 1992. It made a lot of noises, pleasant ones to me, such as mechanical hard drive ...
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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 ...
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What was that old FPS game where you shot rats in a sewer?
In the 1990s, I played an obscure shareware (I believe) FPS game for the PC (MS-DOS) which was closer in technology to Wolfenstein 3D than DOOM. It was rather dark, so I assume it had some sort of ...
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Did the original MS-DOS Quake not have a menu item for freelook, and if so, why?
I know that Quake (the 1996 MS-DOS game) is a "full" 3D engine, and always had some kind of mouse support.
However, even the original Wolfenstein 3D from 1992 also had mouse support from the ...
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How does Laplink achieve "high speeds" on standard/legacy serial ports?
I have been using Laplink Pro 4.0a to transfer files between a modern Windows 10 desktop
PC (via DOSBox) and several vintage DOS computers. Using a standard null-modem serial cable, in my testing it ...
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What's the origin of terminating strings by setting the high bit of the last character?
I was looking at a hex dump of the ROM BASIC from the original IBM PC and found some byte strings like this (ASCII dump is on the right):
50 52 49 4e d4 9d 4c 49 53 d4 9e 50 4f d3 1b 45 PRIN..LIS.....
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Award BIOS error code meaning
I have a faulty Asus SP-97V Pentium motherboard. It doesn't boot, but it definitely takes power and does something.
I plugged a PCI diagnostics card into it, and it shows error codes C0 or C1. It ...
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Quadram odd IBM PC card bracket
I came across an early IBM PC ISA realtime clock/calendar card made by Quadram called the "Chronograph" (picture). It's basically the same clock feature they incorporated into their ...
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Glue to attach rubber feet to a PC case?
I have an old PC case. I spray painted it because it was a little bit rusty. Now I'm trying to attach a set of rubber feet to it, but I have no idea what kind of glue to use.
I tried hot glue, but it ...
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9-pin vs 10-pin serial port ribbon cables
I'm (still) putting an old Pentium PC together. I just found that the connectors of my serial port's ribbon cable have one less hole than needed. The socket on the mainboard has 10 pins, but the 10th ...
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Soltek SL-52B2 motherboard manual
I'm looking for the manual of this motherboard. Google can't seem to find one for this exact model, only similar ones. Help appreciated, thanks!
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Asus SP97V motherboard not powering up
I found an Asus SP97V Pentium-I motherboard. It works with both AT and ATX power supplies. At least it's supposed to, because it actually doesn't.
I put a Pentium 120 CPU, four RAM modules and a ...
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