Questions tagged [ibm-pc]

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

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6
votes
2answers
349 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 ...
15
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5answers
2k 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 ...
18
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3answers
5k 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)...
58
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3answers
17k 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
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2answers
152 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 ...
4
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1answer
315 views

Using floppy disk interface on Future Domain TMC-1680 SCSI ISA card

I have this old card, a Future Domain TMC-1680 ISA SCSI card that has a 34-pin floppy disk connector on it. I am trying to research that to see if I can make it work (before anyone asks - just for the ...
9
votes
2answers
397 views

What PC graphics tech outperformed Sega Dreamcast in 1999?

The Sega Dreamcast was released in 1999 (1998 in Japan) at just the time that the competition for 3D graphics on PCs was intensifying. It's my assumption that a high-end 1999 Pentium II PC with 3Dfx ...
9
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2answers
607 views

How can I read a 5-1/4 drive on 1996-2007 equipment?

In my organization's archive I just found some 5-1/4" 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 ...
43
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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 ...
41
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2answers
9k 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 ...
104
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21answers
35k 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 ...
17
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4answers
22k 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
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4answers
2k views

80286 real mode emulator for 8086

While trying to use a "modern" sound card (an Aztech Sound Galaxy Pro 16 II) in an XT compatible 8086 computer, I encountered the problem that the drivers and tools (like the mixer initialization tool ...
12
votes
1answer
1k views

What manages Upper Memory Blocks (UMBs) in MS-DOS?

I had always assumed that EMM386.EXE was responsible for managing the Upper Memory Blocks - UMBs - the memory space between 640KiB and 1MiB in real mode x86. For example, on MS-DOS 6.22, help emm386....
7
votes
3answers
802 views

Is there really 1MiB of physical memory in the motherboard of a PC AT/XT?

This is a question that has been puzzling me for a while. What happens with devices like graphic cards that have their own memory chips? Do these cards read/write from their own internal memory to/...
6
votes
1answer
695 views

First 80286 Based Computer

The 80286 was released in early 1982. The IBM PC AT, which used it, was released in late 1984. Two and a half years is a long time to design a new computer that is a fairly modest upgrade on existing ...
18
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3answers
2k views

How do CGA emulators for Hercules graphics work?

HGC cards on IBM PCs used to be able to run CGA software by using a CGA emulator. How exactly did those programs work? What were the limitations?
3
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2answers
421 views

IBM 5153 monitor vertical resolution

The IBM 5153, the color monitor accompanying the original IBM PC, was designed to work with the CGA graphics card, vertical resolution 200 scan lines. This was quite unsurprising and straightforward. ...
5
votes
5answers
387 views

Did the PC/AT-bus use its expanded address space?

The system bus of the IBM PC had 8 data lines and 20 address lines, in a logical correspondence to the 8088 CPU. The AT added a second inline edge connector to expand this to 16 data lines and 24 ...
25
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6answers
10k 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 1Gb. Windows ...
9
votes
1answer
673 views

What is this old PC truck game?

I've begun to recall a game I played as a child with my brother, and I can't remember what it was called for the life of me. The reason I'm asking for identification is because I remember how much he ...
7
votes
2answers
490 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 ...
26
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4answers
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 ...
2
votes
1answer
224 views

Power switch color on IBM PS/2 red vs white?

Why do some IBM PS/2's have a red switch, while others have a white switch? Does the red or white power switch on the power supply signify something about the model number, CPU, or options that the ...
27
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2answers
10k 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 ...
3
votes
1answer
142 views

Did the IBM Game Control Adapter have I/O port aliases?

I was taking a look at the logic diagram in the manual for the original IBM game port adapter card: In the upper-left corner of the schematic, there is the circuitry responsible for decoding the I/O ...
50
votes
3answers
12k 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 ...
15
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3answers
1k 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 ...
3
votes
0answers
149 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 ...
13
votes
3answers
1k views

What are the electrical characteristics of a PC gameport?

I'm considering building some custom gizmos to connect to the gameport on my retro-hobby PC (SNES controller adapter, macro/turbo box, etc.) but I haven't been able to find much information on details ...
8
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2answers
2k views

Are game port joystick button circuits more than plain switches? Is this one just faulty?

I'm building a custom interface unit for a game port joystick. To use/test it, I have a CH Products Mach III. (This is the IBM PC version, not the Apple version.) I purchased the joystick for this ...
91
votes
1answer
26k views

Why did MS-DOS applications built using Turbo Pascal fail to start with a division by zero error on faster systems?

On faster MS-DOS systems, it wasn't entirely uncommon for applications built using Borland's Turbo Pascal to fail to start, and (before exiting back to the command prompt) to report a division by zero ...
64
votes
8answers
16k 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 ...
14
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5answers
3k views

What was the first multiprocessor x86 motherboard?

I know dual socket motherboards were around in the 90's before Intel released the Core series. And SMP hardware and operating systems have been around earlier than the PC platform of course. ...
26
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6answers
15k views

Is it true that control+alt+delete only became a thing because IBM would not build Bill Gates a computer with a task manager button?

Is it true that ctrl+alt+del only became a thing because IBM would not build Bill Gates a computer with a button specifically for the task manager? Making it so that Microsoft had to develop a ...
42
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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 ...
18
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4answers
1k 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 ...
42
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2answers
4k views

Locked-up DOS computer beeped on keypress. What mechanism caused that?

Long time ago I had an old IBM PS/2 that I had fished out of a dumpster. It ran IBM DOS 5.0 and was a solid little machine. Occasionally I would encounter the following scenario, and I recently ...
23
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10answers
4k views

Why was hardware diversification an asset for the IBM PC ecosystem?

The IBM PC was cloned very early on, and many third parties made hardware peripherals. This required users to run an OS, install drivers, manage IRQs and hardware bus addresses, etc. Why was this a ...
16
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6answers
4k views

What PC “Clone” technology standards were introduced by clone manufacturers?

IBM famously created the PC standard with the introduction of the first IBM PC in 1981. IBM also extended the standard with the introduction of the PC/AT (1984) and the PS/2 line (1987). However, by ...
6
votes
1answer
249 views

The IBM RAM with non-standard pin layout

One and half decade ago I had an black IBM Thinkcentre tower. The specs were: Pentium 4 2.66 GHz 256 Mb IBM RAM (which later got upgraded into 512 Mb RAM), 40GB HDD, XP Pro SP3, GeForce 2 MX 400. ...
9
votes
2answers
2k 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 ...
7
votes
3answers
354 views

What was the standard size of a PC clone's badge indent?

Generic beige-box PC clones like the ones pictured here often had an indent for the manufacturer's badge to be stuck on. Were these all a standard size, and if so, what were the dimensions?
48
votes
2answers
8k 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 ...
7
votes
1answer
299 views

AT system without -5v

I have recently built a 80386 system. Lacking any AT PSU I connected a PicoPSU using an ATX->AT power adapter. Only card connected was a gpu (Trident TVGA 9000i). System performed BIOS checkup ...
13
votes
1answer
5k 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?
6
votes
1answer
1k views

What was the first third-party commercial application for MS-DOS?

What was the first third-party commercial application for MS-DOS intended for IBM PC-compatible computers?
6
votes
4answers
2k views

High-end PC graphics circa 1990?

I remember CAD being a major driver for PCs with high-end graphics cards; specifically AutoCAD was rising quickly in popularity around 1990 as PCs were able to compete with very costly CAD ...
6
votes
3answers
1k views

Why VGA framebuffer was limited to 64kB window?

VGA framebuffer was fixed to 64kB at A0000h. Right after that there’s MDA/CGA framebuffer at B0000h. I am not sure, but I recall VGA did have to support CGA and its framebuffer, but was there any ...
2
votes
2answers
135 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, ...