Questions tagged [ibm-pc]

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

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3answers
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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 ...
8
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3answers
856 views

Does the 25-pin IBM PS/1 serial port connector contain two serial ports?

I got my hands on an IBM PS/1 computer and it provides a 25-pin serial port connector. Whith the help of an adapter I can get a 9-pin serial port on COM1 and transfer data that way. I would like to ...
8
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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
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2answers
526 views

Origin of Ctrl-Alt-Delete key combination to reset

The Ctrl + Alt + Del key combination to reset is known to me to work on older PC/MS-DOS PCs, some versions of Atari TOS, on runlevel 3 / multiuser.tager Linuxes (it can be disabled). The older of ...
8
votes
1answer
289 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
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1answer
449 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 ...
8
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2answers
715 views

IBM would-be purchase of CP/M

It is well-known that on a sunny day in 1980, when the IBM representatives came knocking on the door of Digital Research, Gary Kildall was still in the air on the way back from visiting another ...
8
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1answer
471 views

AT system without −5 V

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 sequence ...
8
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1answer
524 views

What's the fastest way to ignore keypresses?

I'm writing a game for the IBM PC (running MS-DOS), complete with fancy cutscenes. Unfortunately, though, the keys pressed during those fancy cutscenes are carried out once the fancy cutscene has ...
7
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4answers
631 views

Cost of expansion slots

Among other early computers, the Apple II and IBM PC made the consequential decision to provide internal expansion slots. How much did this add to manufacturing cost? Intuitively, it seems like it ...
7
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4answers
7k views

How do I create a boot menu to select between Windows and DOS?

I was not a PC user before Windows 98. But I remember one of my friends was using a boot menu in his 486 machine to select between Windows/DOS. The menu was like: 1. EMS 2. XMS 3. Windows If we ...
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3answers
1k 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/...
7
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2answers
904 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 ...
7
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1answer
551 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 ...
7
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2answers
459 views

Is it safe to provide 5V to CMOS RAM from PSU instead of CR2032 battery?

I have a motherboard which stores BIOS settings in a DS12887 chip with internal battery. The battery is long dead, and the pin of chip's socket is not connected to any power supply so the chip doesn't ...
7
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3answers
384 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?
7
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3answers
519 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 ...
7
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1answer
2k views

Windows 95 boot disk cannot detect my CD-ROM drive

I have an IBM 466 DX2 with the default CD-ROM drive installed like normal. I wanted to install Windows 95, so I first tried to install on top of the version of DOS already on the hard drive. It had ...
7
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1answer
317 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 ...
6
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5answers
544 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 ...
6
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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
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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
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2answers
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 ...
6
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3answers
446 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 ...
6
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1answer
786 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 ...
6
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2answers
199 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 ...
6
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1answer
391 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 ...
6
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1answer
273 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. ...
5
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3answers
922 views

How can I read COM port addresses from BIOS in QuickBasic 4.5?

I have been using the following code to get comm port addresses from BIOS in QuickBasic 4.5: PRINT "Hex addresses for ports 0 to 3 from BIOS." DEF SEG = 0 FOR x = 0 TO 3 z = &H400 + ...
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2answers
926 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 ...
5
votes
1answer
167 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 ...
5
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3answers
761 views

What was the first integrated PC compatible computer?

When IBM developed the PC, they famously chose a bunch of off-the-shelf components. Besides making the machine relatively easy to clone, another effect of this was it used a lot of chips and board ...
5
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1answer
1k views

Microsoft Flight Simulator 1.0 “DIVIDE BY ZERO” command

I was reading an Wikipedia article named "History Of Microsoft Flight Simulator" and I noticed something weird about Microsoft Flight Simulator 1.0: November 1982 sometime during 1981-82 ...
5
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1answer
398 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 ...
4
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3answers
3k views

Gotek drives for MS-DOS (plus few more constraints)

I have installed two gotek device instead of two old unworking floppy disk drives (in particular on an Olivetti PCS 86). And the result is something like this: (The one on the right should the the A:...
4
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1answer
243 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. ...
4
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2answers
197 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 ...
4
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2answers
206 views

Config information on ancient 16-bit Multi I/O card

I need to build a retro machine so that I can access an HDD that required manual input of BIOS parameters. (Yes, I have that information.) The only ID I can find is ES1O/4A 280695 which yields nothing ...
4
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1answer
391 views

Using a 1995 model M with a modern setup

Looking to get my Model M keyboard working on a modern setup, I believe I need an active converter to go from PS/2 to USB. What adapter / part would be compatible with this keyboard?
4
votes
1answer
334 views

What does it mean when “The Good Old Days” have several seemingly identical downloads for the same game?

This happens for numerous games. If I search, for example, for "Spear of Destiny", I get this: https://archive.org/details/TGODFloppyCollection?and%5B%5D=spear+of+destiny&sin= Four ...
4
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1answer
438 views

Did the 286 go out of its way to follow the 8088 bus protocol?

In general, different CPUs don't use the same bus protocol. A 16-bit CPU would not in general be expected to use the same protocol as an 8-bit CPU. For example, the 68000 would not be expected to use ...
4
votes
1answer
404 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 ...
4
votes
2answers
306 views

With better character handling capability, why didn't PC-98 system succeed in rest of East Asia?

From my understanding, an important advantage PC-98 have over IBM compatible PC was that it is better at handling ideograph based characters which are common in East Asian countries. Why didn't other ...
4
votes
1answer
464 views

Windows 98 Aptiva IBM not booting from CD

I have this old Windows 98 Aptiva IBM which I can't seem to get out of DOS mode or boot from a CD. When I switch it on, it goes through the BIOS checks and then prompts me to click enter to boot or F1 ...
4
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2answers
313 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 ...
4
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1answer
338 views

Operating systems (on support or recent) to install on a i486 processor computer [duplicate]

What operating systems would you recommend for this type of hardware? Though I keep the question text generic because answers can work for many others, but my specific case is a Laptop Siemens ...
3
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2answers
536 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. ...
3
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2answers
302 views

How did databases use the 8087?

A discussion on programs that used the 8087 mentions several categories I expected, and one I did not: Database programs (dBase IV, FoxBase, Paradox, Revelation) The more I think about it, the more ...
3
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2answers
1k views

IBM PC memory map - why RAM at the bottom?

The 8088 provided an address space of one megabyte. The IBM PC allocated that address space as 640K RAM (not that the 5150 could physically take that much, but the address space was allocated) ...
3
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1answer
520 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 ...