Questions tagged [ibm-pc]

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

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9
votes
2answers
834 views

Looking for a specific BASIC music program from the 80s

When I was a kid, we had a PC-XT with a lot of GW-Basic programs on it. I am trying to track down one in particular -- it was a music player of sorts. A menu (all monochrome text as I recall) and you ...
-5
votes
1answer
141 views

Why do old, network-connected consumer computers from 1980-1999 scare me? [closed]

For this question to be answered correctly, it's necessary for me to establish some context. I was born 1985. I'm neither a very young person who grew up with "smartphones", nor so old that ...
6
votes
2answers
181 views

Are there any known 8086 systems that would dynamically switch between XTAL and EFI clocks on 8284 clock generator?

In an typical 1980s 8086 system the 8284 clock chip is typically used to generate the clock for the CPU. The 8284 has two clock sources XTAL and EFI. XTAL provides a steady clock source from a ...
4
votes
2answers
178 views

Detecting the number of disk drives installed

When the BIOS gives control to the MBR (or the bootloader, for non-partitioned media), it passes the drive number from which the bootloader was loaded in the DL register. This number is most of the ...
2
votes
2answers
964 views

Why does changing a DOS/Windows EXE cause it to not run? [closed]

If I hex-edit an EXE for DOS or Windows, by adding or removing some text for example, it will no longer run. If I just change a single char around to a different one, it may run. Is this some anti-...
11
votes
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). ...
24
votes
3answers
5k 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 ...
1
vote
2answers
283 views

Performing 16-bit port I/O on the RTC

Why can’t the RTC (0x70, 0x71) read and write 16 bits at a time? For example: mov ax, 0xa8f out 0x70, ax I have found in a 286 BIOS that did this (BIOS ID string: S286-6181-...
6
votes
3answers
425 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 ...
1
vote
2answers
149 views

Does the Sound Blaster Live! Value had hardware support for Adlib/OPL3?

As I m buying a computer without an onboard sound card, I m thinking about using my old Creative Sound card from 21 years ago and buying a pcie riser adapter instead of a modern sound card (I m ...
13
votes
7answers
6k views

Why did the IBM PC have an internal power supply?

Microcomputers run off low voltage DC, but usually came with a power supply to produce a suitable DC current from the mains AC voltage. It was usual among early home computers to supply an external ...
2
votes
1answer
191 views

Thinkpad 350 keyboard

Am wondering how to use the keyboard from a Thinkpad 350. There are three cables, with 6, 10, and 18 pins (but the big connector on the motherboard seems to have only 17). I assume this is a grid of ...
7
votes
3answers
491 views

Does anyone remember an early 90s side-scroller with a player-controlled ED-209-like robot?

I remember playing a side-scroller at a Babbage's at the mall (on probably a sweet Compaq; I don't think it was on a C64, an Amiga, an Apple, or anything more exotic), probably around 1993, where the ...
65
votes
3answers
13k views

What character is the MS-DOS cursor?

The cursor used on my 486 (and Pentium 3) in MS-DOS 6/7 has a thick underlined character. I cannot find that in code page 437. The underscore character is the closest to it, but is thinner. Where ...
8
votes
1answer
276 views

Lotus 1-2-3 and Microsoft Flight Simulator as unofficial compatibility benchmark?

Do I remember correctly about an unofficial but popular test of "PC compatibility" in the early 1980s? Basically if a machine could run vanilla versions of both Lotus 1-2-3 and Microsoft ...
8
votes
2answers
308 views

What year was my old, long-lost IBM PC born? And which form factor/model was it?

I've spent a ridiculous amount of time and effort over the years just trying to figure out what exact IBM product I grew up with. At last, I've finally established for 100% certain that it was a: IBM ...
10
votes
2answers
10k views

Windows 98 / XP Dual boot

I have acquired an old Shuttle X PC (Windows XP, Mini-DTX form factor HTPC) that works fine. As I can't do much with this form factor (I can't fit a modern motherboard in the case) and that the ...
20
votes
3answers
2k views

How was the 80186 incompatible with the IBM PC?

According to https://en.wikipedia.org/wiki/Intel_80186 The 80186 would have been a natural successor to the 8086 in personal computers. However, because its integrated hardware was incompatible with ...
3
votes
1answer
168 views

Best way to swap IBM PC case badge?

A while back, I purchased an original IBM PC (5150). The seller had an improper top case or badge on it, as the badge actually said it was an XT (5160) instead. After confirming that it is indeed a ...
11
votes
2answers
786 views

How can I read a 5¼″ drive on 1996–2007 equipment?

In my organization's archive I just found some 5¼″ floppies, presumably IBM PC 320/360k. They contain information that we have on paper, but I'd really like to have on electronic media, not least so ...
6
votes
1answer
349 views

Was it ever possible to access the full EGA color space in 200-line modes?

It's long been an established fact that the EGA only had four memory planes, which limited the number of colors on the screen to (24) 16. The best compatible monitors at the time had six TTL color ...
28
votes
6answers
16k views

Windows 98 with 2GB of RAM

I have assembled a retro-gaming PC out of an old Shuttle SN45G with a Windows 98/Windows XP dual boot. The motherboard can handle 2GB of RAM, but apparently Windows 98 can only handle 1 GiB. Windows ...
56
votes
2answers
5k views

Why was the return key symbol ⏎ drawn differently from the motion of a CR-LF?

In the operating system (DOS) of IBM PCs, newlines were represented by a carriage return (CR) character, followed by a line feed (LF) character. The motion of a printer or teletype receiving such a ...
2
votes
2answers
264 views

First 386 PC on sale in the UK

In the early days of personal computers, there was something of a delay in the technology crossing the Atlantic, and when American computers did arrive in the UK, they tended to be expensive relative ...
1
vote
1answer
62 views

Part number / model for IBM PC 350 keyboard

what was the part number or model of the original keyboard shipped with IBM PC 350? Trying to restore the full set.
5
votes
1answer
365 views

Which were the best selling early MS-DOS PCs apart from the IBM PC?? [closed]

The IBM PC in 1981 was rapidly followed by a rich ecosystem of computers with x86 CPUs running MS-DOS, not all of which were compatible at the hardware level. There is a list of some early MS-DOS ...
52
votes
3answers
10k views

On DOS computers, what would the PARK command do?

In 1994 or so, we had an old computer at my primary school. I remember finding out that it had a park command. From reading its documentation, it said that this command should be executed prior to ...
20
votes
2answers
3k views

Did playing sounds on the PC speaker keep the CPU busy?

The IBM PC and early successors came with an internal speaker that could play simple sounds. According to https://en.wikipedia.org/wiki/PC_speaker However, because the method used to reproduce PCM ...
8
votes
2answers
743 views

Could CGA synchronize with vertical blank?

According to http://www.vcfed.org/forum/showthread.php?62049-The-myth-of-the-vertical-retrace-interrupt-on-EGA-VGA IBM first implemented a vertical retrace interrupt on the PCjr in 1984. That ...
12
votes
3answers
2k views

What was the second most common incompatibility in MS-DOS machines? [closed]

When the IBM PC was released, it did not take long for people to figure out that there would be a big market for compatible machines. The first wave relied on MS-DOS as the compatibility layer. The ...
6
votes
1answer
338 views

Was sector size under software control on the original IBM PC floppy drive controller?

The original IBM PC used a 5.25" floppy disk format of two sides, 40 tracks, 9 sectors per track, 512 bytes per sector, for 360K per disk. As I understand it, a significant amount of disk space ...
11
votes
2answers
3k views

Are BIOS ROMs interchangeable among different vendor's PCs?

For PC/AT, 80386, and 80486 machines from the late-1980s through early 1990s (e.g. retro machines, not modern), can you expect to pull a BIOS ROM from one machine and have it work fine in a different ...
16
votes
3answers
2k views

How did the IBM PC handle multiple physical devices serving memory at the same physical address?

I'm trying to figure out how the IBM 5150 PC handled the case where multiple physical devices (memory chips) were mapped to the same address within the 8088's physical address space. The closest I've ...
7
votes
1answer
290 views

IBM PC 5150 board layout

How did the parity check DRAM chips work? In particular, is there a reason for the gap in the motherboard (IBM calls this system board) between the parity check DRAM and the "normal" DRAM ...
4
votes
1answer
235 views

Back in the day, were games coded to run better with more (not faster) RAM? [closed]

Let's say the year is 1999 or something like that. I have a PC with 400 MHz, no graphics accelerator and 64 MB RAM, and try to run some Need for Speed game or something. I notice that it goes laggy. ...
22
votes
2answers
2k views

Which is the minimum set of interrupts/functions I should implement in a replacement BIOS for a home made IBM PC class computer?

I'm at the early stages of implementing a home-made IBM PC class computer (maybe AT class, I don't know yet). The CPU will be an actual 8088 chip, but everything else (except memory) will be ...
23
votes
4answers
32k views

How can I connect a DIN plug keyboard to USB?

I have a wonderful IBM Model M keyboard, which has the best key action of all keyboards I ever used. The problem is it has the big round 5-pin DIN connector used in AT PCs. I have some PS/2 to USB ...
16
votes
5answers
2k views

What specific technical advance(s) allowed PCs to play “Full-screen full-motion” video?

In the early 1990s, the new buzzword for PCs was "Multimedia", and the gold standard for multimedia performance usually talked about was "full-screen full-motion" video playback. Many will remember ...
26
votes
3answers
3k views

What were the HW specifications for the actual PC speakers, before they were replaced by buzzers?

Back in the early 2000s, I remember that, what were at the time older, PC cases had actual loudspeaker instead of the buzzer, which was popular as the PC speaker on the PC cases of the time period. ...
106
votes
22answers
36k views

Was there ever any reason to wait 30 seconds to restart a c.1995 PC?

I owned a PC in the mid-to-late 90s, and while everyone said when you turn it off and back on again, count to 30. But it also had an instant reset button down below. Was there ever really any risk ...
30
votes
3answers
10k 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 ...
17
votes
5answers
5k views

What is most appropriate choice for DOS for a 1990 80386 PC?

I plan to install Windows 3.0 and PC/GEOS on top of DOS. Plus I will install numerous games from the 1984-1992 timeframe. Some of the later games will require >640K RAM and make use of an EMM driver. ...
57
votes
3answers
13k views

Who set the 640K limit?

We all know that "640K should be enough for everyone". But who actually set this limit? The quote is often attributed to Bill Gates, but it doesn't seem like a decision for an Operating System vendor ...
8
votes
1answer
1k views

When did MS Windows get Dual Monitor support?

I remember one of the features I admired on the Macintosh in the late 80s was support for multiple displays. First time I saw this was on an SE/30, using the internal display along with a big external ...
8
votes
1answer
494 views

Was there ever a functional EGA emulator for the Hercules graphics card?

I used to use a CGA emulator (don't remember which one it was), that could show some gfx even in EGA/VGA-only games (when I selected EGA mode). I remember my frustration seeing some garbled graphics ...
44
votes
9answers
12k 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 ...
0
votes
0answers
92 views

Portable 386 that only ever beeps continuously; no video

I've acquired a late-80s portable 386 with builtin LCD in unknown working state. It only ever beeps continuously on boot, with no picture on either the built-in LCD or an external VGA-connected ...
46
votes
8answers
10k 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 ...
13
votes
3answers
1k views

PC/AT two DMA controllers - what is the purpose of cascade channel and how did it work?

Why did the design need to reserve one channel for cascade, how did it work and what exactly was going on there?
4
votes
2answers
299 views

Can a bootable Win9x HDD be made interchangeable between PCs?

Normally, Windows 9x must be installed on each PC individually so that it can be loaded/configured with the appropriate set of drivers. I'm wondering if there is any way to make a boot HDD that can be ...