Questions tagged [ibm-pc]

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

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26
votes
6answers
14k 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 ...
55
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
252 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
61 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.
20
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2answers
1k 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 ...
5
votes
1answer
345 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
9k 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
721 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
319 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
281 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
229 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
30k 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. ...
104
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 ...
29
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
939 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
465 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
83 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 ...
45
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
291 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 ...
10
votes
3answers
913 views

Transferring files between Commodore PET and IBM PC

Suppose you have two early eighties computers, a Commodore PET with 8050 disk drive and an IBM PC with its 5.25" disk drive. Is there a way to transfer files between them? Not machine code programs, ...
12
votes
11answers
2k views

Which pointing devices were used by early laptop computers?

I've started reading this article on the history of the ThinkPad. In it, the TrackPoint (pointing stick/"nipple" mouse) is heralded as an important innovation in the design of portable computers at ...
14
votes
4answers
8k 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 ...
25
votes
7answers
6k views

Purpose of turbo switch on systems unable to slow to 4.77 MHz?

I have a PC with an Intel P133 (133 MHz). The motherboard (PcPartner MB520NH) only allows for it to be slowed down to 75 MHz at the least via jumper settings, but no lower. Yet the PC's case has ...
54
votes
6answers
16k 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?
30
votes
3answers
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. ...
26
votes
2answers
3k views

How did an IBM 5150 with 16KB RAM work?

I keep reading that when it was first released, there was a variant of the IBM PC model 5150 that had only 16KB of RAM installed. From a hardware perspective, this would clearly work - the 5150 ...
68
votes
8answers
17k views

Why did IBM make the PC BIOS source code public?

IBM released the IBM 5150 Technical Reference manual in August, 1981, and included in it the fully commented source code listing for the BIOS. I find this odd for two reasons: IBM must have realized ...
22
votes
4answers
4k views

Why was NEC able to wrestle PC graphics standards away from IBM?

The dominant standards for PC graphics in the 1980s were the ones introduced by IBM. This included MDA and CGA with the original IBM PC, followed by EGA shortly after the PC/AT, and then VGA with the ...
2
votes
1answer
153 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 ...
5
votes
1answer
114 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 ...
22
votes
4answers
6k views

Why was IBM BASIC so Huge?

The early versions of Microsoft BASIC required 4KB of ROM, and many versions existed in the 8KB and 16KB size. But Microsoft's IBM BASIC (known as "Cassette BASIC") for the original IBM PC (Model 5150)...
5
votes
2answers
889 views

Could early nineties PCs access raw CD bitstream?

In the early nineties, as discussed in What specific technical advance(s) allowed PCs to play "Full-screen full-motion" video? it became commonplace for PC games to use the storage capacity ...
12
votes
2answers
1k views

Hard coded hard drive BIOS geometries

Most old BIOSes on PCs and compatibles provided means to enter hard drive geometries (cylinder/head/sector as well as more esoteric things like write precomp) when configuring the machine. Some (AMI ...
30
votes
5answers
3k views

What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The capacity in Amiga Old File System format (OFS, OS version 1.x) was 840KB, with the Fast File System ("FFS" (!)) introduced for OS 2.x onwards able to store 880KB. The PC format stored 720KB on the ...
9
votes
6answers
5k views

Cannot boot from a Compact Flash card

I am trying to fix up an old work computer I have from the early to mid 90's. Everything works fine, but the hard drive makes a horrible clicking noise when it loads anything, so I decided to ...
6
votes
2answers
380 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 ...
16
votes
5answers
3k views

Adding the third floppy drive?

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 ...
59
votes
2answers
18k views

What is the “two-drive trick” that can read Amiga disks on a PC?

Standard belief is that the floppy disk controllers used on PCs are incapable of reading Amiga floppy disks, due to the PC disk controller expecting a very specific low-level format of disks, whilst ...
0
votes
2answers
194 views

IBM PC 5150 motherboard labelling

The motherboard of the IBM PC 5150 has labels of letters followed by numbers. What are the letters representing? Examples being U1, P1, C1, T1 and Y1. I am trying to ascertain which component is the ...