All Questions

Filter by
Sorted by
Tagged with
6
votes
2answers
421 views

Where can I find the Applesoft line-drawing algorithm?

I’m trying to make some graphics in Processing that look just like what I’d get on an Apple //e. I think the info I seek is in the ROM disassembly but I can’t find anything by googling. I'm also ...
3
votes
1answer
126 views

How to write directly to the Commodore 64 (or similar) DAC [duplicate]

I read some related information in a SAM question but I want to know exactly how to write amplitudes directly to the DAC, sample by sample, like in a bytebeat formula. I understand it is possible on ...
63
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 ...
5
votes
2answers
412 views

Did any devices use the Commodore 64 joystick ports as outputs or two-way communications ports?

Looking at the schematic and explanation of how the C64 joystick ports work, it seems clear that the stick direction and button lines (JOYA0, through JOYA3 for port 1 and JOYB0, through JOYB3 for port ...
2
votes
1answer
155 views

Xerox 3700 Documentation?

Cannot find any documentation on this computer, need some help identifying it. I am pretty sure this is some kind of print server and the date on the parts is 1989.
1
vote
3answers
252 views

When was Tantalum first used in computing?

I know that nowadays Tantalum is very common in computer components, specifically capacitors, due to its desirable electrical properties. I'm curious when it was first used specifically in the ...
11
votes
3answers
614 views

0xF1 opcode-prefix on i80286

On intel IAPX 80286, as I recall from experience, the undocumented - officially unassigned - "opcode" position 0xF1 was actually decoded as an instruction-prefix, thus counting for maximum allowed ...
4
votes
0answers
225 views

First use of “destructuring” in computing?

Which programming system first introduced "destructuring" denoting accessing various parts of an object using some sort of pattern, and binding those parts to variables, like Common Lisp's ...
2
votes
2answers
284 views

How can I extract game data from Nitemare 3D files?

I am trying to reverse engineer an old Wolf3D style Dos game named "Nitemare 3D". I can get a raycasting engine with directional sprites running pretty easily using SDL2, but I have no experience with ...
11
votes
1answer
323 views

Unix utility “smiley” to decode emoticons: Where to get it?

I remember in the 90s, there existed a Unix command line utility named smiley that decoded emoticons. A sample use would be like this (the output is likely not the exact output the program gave): $ ...
4
votes
1answer
373 views

Why did MS BASIC use the line number for FOR loops?

I was always under the impression that MS BASIC implemented NEXT by pushing the address of the FOR on the stack. So convinced that when I read the source code I assumed CURLIN had to be referring to ...
13
votes
2answers
581 views

Atari ST DRAM timing puzzle

From the Atari SM124 Monochrome Monitor Service Manual, I get that the video signal timing for one line is 20µs. With the horizontal resolution of 640 pixels, this gives a 31.25ns pixel clock. Using ...
11
votes
1answer
1k views

Why was CPU32 core created, and how is it different from 680x0 CPU cores?

I am doing a design based on the Motorola 68332 MCU made for embedded applications, which is based on the CPU32 core. The CPU32 core is very similar to the 680x0 CPUs, but there are some subtle ...
1
vote
0answers
117 views

Identify Toshiba CRT

Didn't find anything with a search and need to replace the tube due to it being severely burnt in. [] []
14
votes
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. ...
3
votes
3answers
246 views

Steps to recover data from Conner CP341

Trying to recover data from Conner CP341 HDD i took from an old Compaq Portable III. The data is important enough to go through the effort of recovering it, and i would like to do this myself (rather ...
0
votes
2answers
350 views

What 486 motherboard is this, with American Megatrends BIOS identifying is DPAQ-6156-043090-KF?

I've got an early 486 motherboard that doesn't seem to have a manufacturer name or FCC number on it and I'm having trouble identifying it. I've placed some photos of the motherboard in this Imgur ...
4
votes
2answers
293 views

Reference material for building a DIY Stack Computer from Logic Gates

I've been following Ben Eater's series of videos about designing a small computer from discrete logic gates, I'm curious if there is a similar tutorial/book/reference for building a stack computer. I ...
26
votes
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 ...
17
votes
2answers
1k views

What was the role of Commodore-West Germany?

Most of the history of Commodore in personal computers took place while East and West Germany were divided, and Commodore maintained a significant corporate presence in West Germany. While I believe ...
2
votes
0answers
124 views

What was the influence of the 'Legion of Doom' and the e-zine Phrack on early computer culture? [closed]

I was reading a bit about the 'Hacker Manifesto' written by Loyd 'The Mentor' Blakenship and was also reading about the hacker group 'Legion of Doom' and was wondering what influence these groups / ...
17
votes
3answers
2k views

How to switch an 80286 from protected to real mode?

It's pretty well documented how to get the 286 from real mode to its 16-bit protected mode. It's also widely stated that the 286 had no officially supported way of going back from protected mode into ...
25
votes
1answer
430 views

Why were pipes removed from the Lisa?

I was recently looking at some documentation for programming the Apple Lisa: https://lisa.sunder.net/LOS_Reference.pdf and I was surprised how advanced it was for the time. It had a lot of features ...
11
votes
1answer
2k views

3 beeps on a 486 computer with an American Megatrends bios?

So far I've figured out that means something about the ram bit I haven't been able to figure out what the problem is Edit: video link
2
votes
2answers
404 views

Anyone heard of 'something like' EDITLN or EDITLINE or LINEDIT statement in BASIC?

Anyone heard of 'something like' EDITLN or EDITLINE or LINEDIT statement in BASIC for editing lines of a program's own code while executing ? I seem to remember a statement that was spelled '...
12
votes
2answers
808 views

IBM mainframe classic executable file formats

Most modern platforms have pretty well-defined file formats; e.g. Windows uses PE, Linux and BSD - ELF (previously a.out), macOS - Mach-O, AIX - XCOFF and so on. What were (are?) common executable ...
12
votes
3answers
510 views

How was concurrent programming achieved on the PDP-10?

A useful way to do concurrent programming is, say, a Compare-And-Swap instruction, which really is two operations, executed one after the other, atomically. This was available on the IBM 370 and on ...
3
votes
0answers
251 views

How do Apple II BASIC compilers compare? [closed]

Programs like The Beagle Compiler allow AppleSoft BASIC or other Apple II BASIC variants to be compiled. How do the compilers compare in terms of speed, compatibility, and features?
13
votes
3answers
457 views

Did any micros use the 6502 BCD mode in their OS?

I know the Atari's FP package used BCD for rather dubious reasons, but does anyone know of other examples of basic "operating system" level code on common platforms that used BCD? I suspect BCD was ...
12
votes
1answer
330 views

How did restarts resolve parity errors triggered by broken core-rope wires?

In his account of the history of the Apollo Guidance Computer, Don Eyles describes the role of a parity bit as follows (p. 80): ... if one of those hair thin wires in our woven core-rope memory ...
7
votes
3answers
634 views

What were the first chips with hardware support for SPI?

The SPI four-wire serial bus is a very common interface between chips and other small devices these days, but was originally developed by Motorola in the mid-1980s. What were the first Motorola and ...
7
votes
3answers
398 views

How is PETSCII used by assembly-language programs?

First, a bit of context. I wrote an interactive disassembler for 6502 code that, among other things, attempts to identify ASCII strings automatically. Appropriate source code for different assemblers ...
5
votes
1answer
358 views

How was text handled on the Amstrad CPC 464?

The three official video modes described on the CPC wiki are all bitmap modes, and this page mentions that the "screen is bitmapped. You must draw/erase your own sprites and text." So what was the ...
14
votes
1answer
982 views

What's the timeline of Motorola 6800-family CPUs from 1974 to 1979?

According to Wikipedia, The Motorola 6800 was released in 1974. Between that and the release of the 6809 in 1979 (or 1978?) there was at least one other 6800-series CPU released, the 6802 ...
2
votes
1answer
206 views

What is a more featureful and/or better coded 6800 disassembler for modern machines than f9dasm?

I'm currently using [this version of f9dasm] on Linux to disassemble a moderately large Motorola 6800 program (Altair 680 Basic, about 8 KB in size). f9dasm isn't too bad, but I'd prefer to use ...
1
vote
0answers
215 views

What technologies were used to harden Windows against Bluescreens [closed]

Quoting a comment from this question: Why did Windows 95 crash the whole system but newer Windows only crashed programs? "A lot of effort has gone into automatically enforcing that drivers are more ...
7
votes
1answer
328 views

How did the Sinclair compare on price with the C64 in the UK?

As far as I know, the popular low-end home computers in the UK around the mid-1980s were the Sinclair ZX-Spectrum ("Speccy") and the Commodore C64. I know the BBC micro also had a following, but my ...
5
votes
2answers
227 views

Are there any CPUs or MCUs object-compatible with the 6800 that have additional index registers or addressing modes?

Having only a single index register and no addressing mode indexing against 16-bit addresses in memory seems to have been widely considered a primary reason that the Motorola 6800 fared poorly in ...
12
votes
7answers
2k views

8086 stack segment and avoiding overflow in interrupts

This is a followup to Could the Intel 8086 CPU have many segments in memory of the same type? In the event of a hardware interrupt or user interrupt through the INT instruction, was there a risk that ...
27
votes
5answers
14k views

Why did Windows 95 crash the whole system but newer Windows only crashed programs?

Example situation. You are using a program in Windows 95 and screen goes blue only for you to restart the whole computer You are using a program in Windows 7 and the program stops responding only to ...
39
votes
6answers
9k views

How did the SysRq key get onto modern keyboards if it's rarely used?

Was the SysRq key ever used on any common operating system? Google tells me it wasn't. But then how did it end up on so many keyboards?
3
votes
3answers
235 views

Interrupt pin type on the 6502

I have a really basic question. I have to design an 65C02-based personal computer for a school project. I have to draw my own footprint for the 65C02. My question is what type of pin is the IRQB (...
9
votes
7answers
924 views

Low-cost sound chip

I want to make a homebrew 8-bit computer and I want to include a sound chip in it. It needs to be as cheap as possible (under 5$) and I also want it to be possibly controlled by an Arduino or ATmega-...
4
votes
1answer
142 views

Was there any VIC-20 expansion to bring memory beyond the default maximum of 40 KiB?

The Commodore 64 was very flexible in terms of how RAM could be controlled. ROMs and I/O devices could easily be swapped out by setting bits in the first two addresses of memory. The VIC-20's ROMs and ...
8
votes
1answer
460 views

Will any serial mouse connect to Classic Macs?

The Macintosh 128k, 512k, and Plus use a DE-09 Serial port for the mouse. Is there some proprietary data-transfer method? Or is any DE-09 Serial mouse compatible? Furthermore: has anyone documented ...
5
votes
5answers
356 views

Could the Intel 8086 CPU have many segments in memory of the same type?

The Intel 8086 CPU could address up to 1 MB of memory using segmentation, and this CPU have 4 segment registers, which are CS and SS and DS and ES. Each segment in memory can have a maximum size of ...
17
votes
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 ...
13
votes
5answers
2k views

Does the Intel 8086 CPU have user mode and kernel mode?

Does the Intel 8086 CPU have user mode and kernel mode as modern CPUs do? and if it doesn't have user mode and kernel mode, does that mean that any user program written for the Intel 8086 CPU could do ...
4
votes
0answers
299 views

Why is the original Altair BASIC (for the 8080 CPU) source code not available on-line?

As described by The Register in 2001, around 1987 journalists and others started asking Bill Gates for a copy of the source code for the original version of Altair (eventually Micro-Soft) BASIC, ...
5
votes
3answers
285 views

In what way does the Straight-8 expand on the PDP-5?

A quote from the Wikipedia: The PDP-5's instruction set was later expanded in its successor, the PDP-8, to handle more bit rotations and to increase the maximum memory size from 4K words to 32K ...

15 30 50 per page