Questions tagged [ibm-pc]

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

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12
votes
1answer
497 views

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 ...
14
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7answers
3k views

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, ...
23
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1answer
2k views

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 ...
34
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4answers
8k views

How much did IBM save by limiting the PC to 4.77 MHz?

My understanding is the CPU clock speed on the Intel 8088 in the IBM PC was selected as 4.77 MHz to simplify the design of the system. This despite the 8088 coming in two versions - 5 MHz and 8 MHz. ...
0
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0answers
150 views

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 ...
29
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1answer
7k views

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 ...
2
votes
2answers
454 views

What was the DRAM refresh interval on early microcomputers?

Dynamic RAM is denser than static RAM, but needs to be refreshed every few milliseconds to avoid losing data. How many milliseconds, exactly? If the answer has changed over time, then I'm interested ...
1
vote
0answers
295 views

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 ...
13
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2answers
2k views

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 ...
17
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3answers
3k views

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 ...
30
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6answers
6k views

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 ...
8
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2answers
2k views

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 ...
13
votes
1answer
791 views

What was the intended use for the character symbols for control codes in codepage 437?

Is there a well documented or well understood explanation for what was the intended purpose for the more haphazard glyph choices in the control code range of the original IBM PC character set? Maybe a ...
10
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5answers
742 views

Where are the authoritative specs for legacy PC/AT devices still in use in today's PCs?

For example, the 8250/16550 chip used to handle serial communication is still simulated by modern chipsets and is enumerated by ACPI as PNP0500/PNP0501. You can find datasheets for these chips. ...
28
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5answers
4k views

What really is a sound card driver in MS-DOS?

To my knowledge, neither MS-DOS nor BIOS offers any kind of API for sound cards. Therefore the concept of a "driver" is absent, as we know it today. Apart from accessories and sample files ...
20
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3answers
5k views

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 ...
45
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2answers
7k views

Did IBM encourage Bill Gates to retain the rights over PC-DOS?

As is well-known, Microsoft's negotiations with IBM to deliver PC-DOS 1.0 with the original IBM PC resulted in: IBM licensing the OS from Microsoft, as opposed to purchasing it outright. Microsoft ...
15
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4answers
2k views

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 ...
49
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6answers
8k 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 ...
11
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3answers
1k views

Default (as opposed to physical) read/write heads - what are they?

The Seagate U Series hard disk Product manual states that the drive has 16 "Default read/write heads" while it has 4/3/2/1 "Physical read/write heads" (depending on actual model). ...
11
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1answer
1k views

How can I edit CMOS hard drive geometry settings on a 1991 PC?

First, I am NOT asking how to use the BIOS Setup utility. I'm asking how to OVERRIDE the built-in settings my BIOS Setup supports for the HD geometry. I have a 1991 NCR PC with a 386SX, on-board IDE, ...
38
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4answers
9k views

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 ...
-1
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3answers
319 views

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 ...
15
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7answers
5k 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 ...
7
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0answers
288 views

What are the differences between MS-DOS and DR DOS FASTOPEN?

OS/2 Museum's history of DOS mentions the FASTOPEN.EXE TSR was introduced in DOS 3.3. Its entry on DOS 4.0 adds some implementation details. It reminded me of the DR DOS FASTOPEN=nnnnn directive in ...
14
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5answers
1k views

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 ...
10
votes
3answers
3k views

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 ...
39
votes
11answers
7k views

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.....
25
votes
1answer
4k views

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 ...
16
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2answers
6k views

What is the oldest commercial MS-DOS program that can run on modern versions of Windows without third-party software?

What is the oldest commercial MS-DOS program that can run on modern versions of Windows (such as Windows 8.1 or Windows 10) without third-party emulators?
22
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2answers
2k views

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 ...
12
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3answers
2k 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 ...
3
votes
1answer
220 views

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 ...
4
votes
1answer
122 views

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 ...
5
votes
4answers
1k views

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 ...
3
votes
0answers
159 views

PC AT power supply not providing correct voltage

I'm refurbishing a Pentium 120 PC with an AT power supply. It seems to work, at least nothing pops or smokes, but there's a slight problem with voltages, particularly on the motherboard connectors. ...
47
votes
9answers
13k views

Why did the IBM PC need a sound card?

The original IBM PC and later variants used an Intel 8253 or 8254 as a sound chip. Why did users add sound cards such as the Adlib or Sound Blaster. I remember voice output with programs like ...
2
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0answers
69 views

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!
2
votes
1answer
105 views

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 ...
5
votes
2answers
361 views

Can I power a Windows 95-era AT PC with an ATX PSU, like this?

Is this the correct way to make the adapter? Will the "15A 120V AC ONLY" switch damage anything? The switch is illuminated. (glows when off)
26
votes
3answers
6k views

Why does DOS ask for the current date and time upon booting?

In most versions of DOS, when they are started from a medium that lacks an AUTOEXEC.BAT file, the very first thing COMMAND.COM does is ask the user to confirm the current date and time: Starting PC ...
11
votes
1answer
455 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 ...
9
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2answers
2k views

Looking for a 90's shooter-platformer game

Back in the 90's I remember playing a 2d shooter-platformer game on my family's home computer. I sucked at the game, and as far as I remember I never managed to beat the first level. The details I can ...
10
votes
2answers
387 views

How do I terminate an ISA bus correctly?

I am stuck by designing a 8 Slot 16 Bit ISA Backplane Do I have to terminate an ISA bus? My search results are: No termination at all Some homebrew projects use active termination for all signals ...
33
votes
3answers
11k views

Why do PCs boot in 720x400 resolution?

Using my 21" Trinitron OSD, I can see that the resolution at boot is 720x400. From memory, this weird resolution is extremely uncommon if ever to be seen as a choice on software that supports ...
10
votes
3answers
1k views

How to repair paint on IBM PC?

I have an IBM XT 286 which has essentially the same case as the original IBM PC. It has a few minor blemishes, some places where the paint has been chipped off, and some tiny spots of rust. How should ...
48
votes
9answers
11k views

Why weren't bootable game disks ever common on the IBM PC?

While for other platforms of that era (primarily, Amiga), putting a game on a bootable disk was quite a normal practice, this approach never taken off on IBM PC. Why not? I do remember people having ...
11
votes
2answers
497 views

AdLib, YM3812 and Timers

For no particular reason I started reading up on the original AdLib Music Card, and it's clear that this card was little more than a stock Yamaha YM3812 music chip (aka OPL2) glued to a PC's 8-bit ISA ...
6
votes
2answers
737 views

Why did CGA RGBI output leave DAC to the monitor?

CGA on the original IBM PC produced sixteen colors, one bit each for red, green, blue and overall intensity modifier. The preferred output device was the later-arriving 5153 color monitor, which ...
9
votes
2answers
439 views

Why does MS-DOS 5.0 EDIT hang on my XT-class machine with a German 102-key keyboard?

Most times whene I call EDIT on my XT-class machine with MS-DOS 5.0 installed on the hard disk, the menus of EDIT appear, but the window that should contain the file contents stays blank and the ...

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