All Questions

Filter by
Sorted by
Tagged with
5 votes
3 answers
656 views

What is the purpose of the M1 pin on a Z80

I've been looking through bits of documentation about the (sadly recently discontinued) Z80 processor and the machines people have built with it. One thing I noticed is pin 27, called "M1", ...
Stormcloud's user avatar
0 votes
0 answers
119 views

Physical server with LED display on case, possibly programmable

Sometime in the 2000s I was in the server room of a customer site. This was still in the days of largely on-premise, not necessarily rack-mounted server boxes. A guy from their hardware vendor was ...
Alan B's user avatar
  • 4,790
4 votes
0 answers
205 views

Why does the boot-up screen for Cruis'n USA (arcade version) display this strange text?

(I originally asked this in the "gaming"/Arqade section. However, it was suggested by a commenter that I should instead migrate it here. Since I don't know how one "migrates" a ...
user296681's user avatar
2 votes
1 answer
106 views

Commodore 128 bottom row of keys work with different shift keys

I have been playing with a Commodore 128 that I picked up but I have noticed one, what I would call, weird keyboard problem(?). If I an on the bottom row of the keyboard every other key works with a ...
GaryFDes's user avatar
0 votes
2 answers
228 views

DEC's "decimal ASCII"?

I'm reading some older FOCAL documents and see references to things like... SETS X TO THE DECIMAL ASCII CODE OF THE INPUT CHARACTER A bit later there is a table of these codes, and unless I am not ...
Maury Markowitz's user avatar
14 votes
3 answers
2k views

Were there 3D accelerators built on discrete logic?

I wonder if there were 3D accelerators (that is, a device that calculates rotations, scaling, texturing, etc. for 3D points) built on discrete logic (7400 series, most likely its fastest variants, ...
Alex's user avatar
  • 611
2 votes
1 answer
138 views

Connecting the PHI2 pins on W65C22 [closed]

A year ago, I started designing my own 8-bit CPU with discrete transistors (I know this is a crazy goal, but I'm mostly doing it to learn). Now before I order everything for my CPU, I created a PCB ...
MathijssY Klaver's user avatar
4 votes
0 answers
202 views

Is the source code of Alan Dain Sample's m5 macro processor lost?

I've recently come across the User's Guide to the M5 Macro Language by Alan Dain Samples. The guide says that the source code is available at thor.ece.uc.edu:pub/dain/m5. However, this seems not be ...
René Nyffenegger's user avatar
4 votes
0 answers
214 views

Looking for early examples of extended precision by interpretation

The other day I came across a clever way of implementing variable-length extended precision, dated 1967 (on the BESM-6, apparently as part of the system software available at the time of introduction ...
Leo B.'s user avatar
  • 19.4k
0 votes
0 answers
100 views

Where can I get 16K x 1 DRAM in ZIP package? [closed]

Where can I get 16K x 1 DRAM in ZIP package which I need for fixing an old device?
Paul Cohen's user avatar
5 votes
1 answer
889 views

Why did the UNIVAC 1100-series Exec-8 O/S call the @ character "master space?"

It was used as a sentinel character in card images. It distinguished job control commands from data. But why the strange name?
Jess Fuckett's user avatar
-3 votes
0 answers
131 views

Was there a CGA video projector? [closed]

Was there an EGA projector? I wrote 3D software for both, but the customer demo was on a teeny monitor in a big conference room.
Jess Fuckett's user avatar
3 votes
1 answer
255 views

Why didn't Commodore run the 6502 at 2 MHz? [closed]

The Atari 800, in 1979, ran the 6502 at 1.79 MHz. That rounds to 2, and was presumably a 6502A rated for 2 MHz, underclocked. Why did Commodore keep running their 6502 computers at 1 MHz, even the 64 ...
rwallace's user avatar
  • 62.8k
6 votes
1 answer
984 views

BIOS support for 286 Protected Mode

Did BIOS on 286 systems provide support for the Protected Mode? On a 386, the BIOS can be fairly easily accessed from protected mode using the Virtual 86 mode, but since 286 did not officially support ...
TrayMan's user avatar
  • 163
7 votes
1 answer
663 views

Which computer first used stored characters (shape selector) and character bit patterns in the same memory

On the Commodore VIC-20, the VIC chip alternates between cycles where it fetches a byte from screen memory that identifies a character (and also a nybble from color memory), and cycles where it ...
supercat's user avatar
  • 37.3k
8 votes
1 answer
2k views

Why was the SNES color gamut RGB?

The SNES color gamut is 15-bit RGB. On the face of it, that makes sense for a 16-bit machine. But. The color generators on some earlier machines like the Atari 2600, Commodore 64, NES, were not ...
rwallace's user avatar
  • 62.8k
16 votes
2 answers
4k views

Did the NES CPU save die area by omitting BCD?

The NES CPU was a copy of the 6502 with the BCD circuitry removed. As I understand it, this modification was motivated by a theory that BCD was the only part of the 6502 that was actually patented, so ...
rwallace's user avatar
  • 62.8k
18 votes
6 answers
5k views

How did the `long` and `short` integer types originate in C?

I was wondering why C has the long and short integer type in addition to the plain int, and came across the following quote in the C99 Rationale (thanks to this answer here): [...] In the 1970s, 16-...
user51462's user avatar
  • 511
5 votes
1 answer
518 views

Where can one find "the Puzzle benchmark" from Hennessy’s MIPS paper?

I'm reading Hennessy's original MIPS paper. At the end, it includes estimated performance using "The Puzzle benchmark". The reference for this reads: Baskett, F., "Puzzle: an informal ...
Maury Markowitz's user avatar
10 votes
1 answer
1k views

Did any Famicom game use microphone for random seed?

So I know most common way to generate pseudo-random numbers on Famicom or NES is linear feedback shift-register. However... It came to my mind - Famicom controller has a microphone. Did any game ever ...
shinobody's user avatar
  • 201
0 votes
0 answers
111 views

SATA to ATX 1.0&1.2 6-pin CPU AUX adapter (old AT power connector, AUXPWR, EAUXPWR) [closed]

I was thinking to create an adapter for this old connector using a SATA power cable and extension. I've harvested the 6 pin connector from an old Pentium 4 PSU, so I just want to splice it on the SATA ...
Wes's user avatar
  • 109
16 votes
5 answers
4k views

Why was the 1540 a computer in its own right?

The Commodore 1540 disk drive, along with its better-known successor the 1541, is a computer in its own right, with its own 6502 CPU. Why was it designed like that? It adds significant cost to the ...
rwallace's user avatar
  • 62.8k
7 votes
1 answer
562 views

What was "Mac SLM" or "ASLM"?

While looking through a very old codebase, I found some preprocessor defines and comments referring to something called "Mac SLM" or "ASLM". From the context, it appears to have ...
Mark's user avatar
  • 8,677
7 votes
0 answers
217 views

The works of Frontier Manufacturing

Having spent the last however many decades believing Commodore Semiconductor Group was a simple rename of MOS Technology, I just watched a video – quite interesting in its own right – which casually ...
rwallace's user avatar
  • 62.8k
3 votes
0 answers
261 views

What process node enabled the 6502 to reach 2 MHz? [duplicate]

The original version of the 6502 was rated for 1 MHz, but before the end of the decade, the CPU was available in a 2 MHz version. Presumably what changed was Dennard scaling: make the transistors ...
rwallace's user avatar
  • 62.8k
37 votes
4 answers
6k views

I buy retrocomputing devices, but they set my allergies off. Any advice on sanitizing new acquisitions?

I have had allergies in the past, mold, grass, and other causes of hay fever, also dust and cigarette smoke. I like getting old 8 bit systems, untested, and getting them to work. So far mostly for my ...
scm's user avatar
  • 1,059
3 votes
3 answers
357 views

Were jailbars inevitable from VIC-II analog output?

I just watched an interesting video on the imperfections of video output on the Commodore 64. Among other things, he seems to be saying the commonly observed 'jail bars' effect is a result of other ...
rwallace's user avatar
  • 62.8k
4 votes
1 answer
258 views

My Amiga 500 "Enter" and "Return" keys wont work... possible causes?

I recently bought an almost working Amiga 500. When I got the unit in, I found that it mostly worked, the floppy drive spindle needed greasing, and the ram expansion just needed re-seating... but ...
scm's user avatar
  • 1,059
2 votes
0 answers
243 views

What is this PSU connector? Compaq Portable motherboard

I've lost the PSU wiring harness to my Compaq Portable motherboard in a move and I'm trying to figure out what connector this is. Here's a picture with some AT-era Molex connectors for perspective. ...
Katastic Voyage's user avatar
9 votes
2 answers
530 views

How did the PL/I designers not understand environments?

In Charles Lindsey's “A browse through some early bulletins”, he mentions (regarding Knuth's Man Or Boy test): As a postcript to this whole episode, it may be noted that a couple of years later Bekic ...
texdr.aft's user avatar
  • 3,627
11 votes
1 answer
395 views

What was the 6-bit length instruction(s) in the Intel iAPX 432?

The iAPX 432 was arguably the most complex processor architecture ever and a commercial failure for Intel. It was a stack machine with no visible general-purpose registers. It had hardware support ...
DrSheldon's user avatar
  • 16.3k
19 votes
3 answers
3k views

What terminal did David connect to his IMSAI 8080?

Since it seems that we are now accepting questions to identify-this-peripheral from a movie, we might as well address the quintessential Retrocomputing movie... What terminal is David using at home in ...
DrSheldon's user avatar
  • 16.3k
2 votes
1 answer
173 views

When were the late 70s FCC regulations introduced?

According to https://en.wikipedia.org/wiki/TI-99/4A Through the development period, several companies attempting to enter the home computer market were faced with significant pushback from the ...
rwallace's user avatar
  • 62.8k
3 votes
0 answers
148 views

Did Commodore have an alternative chip company acquisition target?

One pf the pivotal historical events of the 8-bit computer industry was the acquisition by Commodore of MOS Technology in 1976. This gave Jack Tramiel the vertical integration he wanted, and led ...
rwallace's user avatar
  • 62.8k
2 votes
1 answer
217 views

Printztronic on modern TV

I have been provided with a Printztronic Videosport 800 to try and get working. New batteries and plugged in via COAX triggers a TV response, but I only have a couple of smart TVs which are not easy ...
Reuben Mallaby's user avatar
17 votes
1 answer
3k views

Which program is used in this shot of the movie "The Wrong Woman"

There is a software screen shown at minute 4 in the 1995 movie The Wrong Woman. What Software was used?
elbarna's user avatar
  • 2,341
5 votes
0 answers
140 views

Has any information survived about OS BAMOS for BESM-6, written in DDR?

Recently I learned that there was an operating system for the BESM-6 mainframe developed in DDR: a bibliographical list includes and quite a few more German-language publications (up to item 105), ...
Leo B.'s user avatar
  • 19.4k
6 votes
1 answer
191 views

Repairing an Old CRT Monitor (IBM 5153)

I acquired a used IBM 5153 monitor. The model number is 5153002. It was manufactured in Taiwan and supports AC100-250V. When I first powered it on, the monitor turned on, but nothing appeared on the ...
Sung's user avatar
  • 509
4 votes
2 answers
3k views

How did wolfenstein do 3D graphics when 3D graphics couldn't exist? [closed]

Did they use trigonometric functions to place every pixel on the screen independently? It seems like you could rotate the camera 90 degrees, and the scene would refresh much faster than all those ...
Jess Fuckett's user avatar
5 votes
5 answers
1k views

How much extra did a color RF modulator cost?

I've been doing more reading about the early 8-bit home computers, a fascinating era, in which the cost of the hardware was of course a constant, dominating constraint, and trying to understand ...
rwallace's user avatar
  • 62.8k
3 votes
2 answers
332 views

NES vs SMS ROM speed

The NES used a 6502-derived CPU at 1.79 MHz. The Sega Master System used a Z80 at 3.58 MHz. How did they differ in terms of what speed grade ROM they required in their respective cartridges? I know it'...
rwallace's user avatar
  • 62.8k
33 votes
2 answers
7k views

How did ALT + F4 become the shortcut for closing?

This is another in a long line of computer history trivia questions. It is very much related to this question. How did Alt + F4 become the close keyboard shortcut? I always used that close command on ...
Neil Meyer's user avatar
  • 6,869
12 votes
7 answers
5k views

Why didn't CPUs multiplex address pins like DRAM?

An important innovation for dynamic RAM was multiplexing address lines, so a 2^N-bit chip only needs N/2 address pins, which helps keep cost down. Why didn't CPUs match this? Setting aside e.g. the ...
rwallace's user avatar
  • 62.8k
5 votes
2 answers
845 views

Arcade game similar to Commando, but better music

I'm trying to find the ROMs for an arcade game I played circa 1987. It was very similar to Commando in general concept - vertical scroller, very simple isometrics, guns and grenades. Although it was ...
Maury Markowitz's user avatar
16 votes
2 answers
3k views

How reliable is the floppy content listing information on a C64?

According to this answer, directory listings are generated by the C64 disk drive on the fly: The disk drive creates a pseudo-BASIC-program when the C64 reads from a file named "$". This ...
Mecki's user avatar
  • 263
-1 votes
1 answer
223 views

Installing MS DOS 6.22 under VMWARE

I want to install MS DOS 6.22 as a guest os under VMWARE. I have a bootable msdos.iso file. When I try to create a new guest using this image file VMWARE successfully boots from this file and gives an ...
hptsb's user avatar
  • 115
8 votes
1 answer
381 views

Was the single-level store (SLS) really a breakthrough?

I am reading Pugh's book on IBM, specifically the section on Future Systems (FS). There were two key concepts in FS: high-level language support (HLS), and a single-level store (SLS). Both were ...
Maury Markowitz's user avatar
15 votes
2 answers
665 views

Why did Acorn use the 6502?

It is an interesting quirk of the British microcomputer industry, that the main vendor of cheap microcomputers, Sinclair, used the better, more expensive CPU (Z80), whereas the main vendor of better, ...
rwallace's user avatar
  • 62.8k
-5 votes
4 answers
487 views

Why were floppy disks and hard disks chosen as the boot device for most PCs? [closed]

Why were floppy disks and hard disks chosen as the boot device for most PCs (only recently replaced by NAND flash)?
Yuhong Bao's user avatar
11 votes
1 answer
376 views

What's the earliest source for the legend of Gary Kildall's airplane snub?

A commonly repeated (and commonly debunked) legend describes how Gary Kildall blew his chance at writing the operating system for the IBM PC. Examples include the following: …legend has it that ...
Psychonaut's user avatar
  • 7,681

15 30 50 per page
1
2 3 4 5
122