All Questions

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 ...

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 / ...

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 ...

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 ...

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

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 '...

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 ...

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 ...

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?

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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?

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 (...

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-...

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 ...

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 ...

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 ...

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 ...

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 ...

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, ...

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 ...

On the C64 there was no threading, so how did games handle treating at the same time music and game code? Music requires exact timings, and the SID had to be instructed to change the note at the right ...

I'm trying to understand the difference in bus cycles, clock cycles and states within a 68000 processor. According to the user manual, A bus cycle consists of eight states... Lets assume the 68K ...

(Note: by "object-compatible" I mean that the opcodes and their following operands are the same—the assembler produces the same output for equivalant assembler mnemonics. This of course excludes ...

The Nintendo Game Boy has RAM called "HRAM" (meaning "high ram") decoded at locations $ff80 through $fffe. (All other decoded locations in the $ffxx page appear to be I/O device and system control ...

From the Wiki: The final major release of BASIC-80 was version 5.x, which appeared in 1981 and added support for 40-character variable names, WHILE...WEND loops, dynamic string allocation, and ...

Was there some particular design theory or constraint that made a 36 bit word size attractive for early computers? As opposed to the various power-of-2 word sizes which seem to have won out?

In Windows 3.X we had multiple type of error dialogs that could be displayed: Application crash: Application error that could be recovered: What did the Ignore button do in Windows 3.1 when an ...

I want to have my computer listen to messages between my Nintendo GameCube and a controller. (This is just for fun, not for streaming or anything.) I've spliced into the cable as described here in ...

Looking over old BASICs I find two general approaches to handling string variables. HP/Wang/Atari/et al used C-like array-of-char whose memory size is specified with a DIM statement, with the upside ...

I bought an Apple IIgs recently. I didn't do my research well enough and wound up with an M1297 monitor, which of course appears to only be compatible with Macintosh IIs and such, rather than the ...

While early microcomputers used analog video outputs (often to use a television as a display), higher end machines such as the BBC Micro or Commodore 128 supported a digital RGB (or RGBI) video output....

Everyone who used early telecommunications services, not to mention the early dial-up Internet services, is familiar with the tones and hissing sounds of a modem establishing a connection. I recall ...

This is inspired by the question "What does a Nintendo Game Boy do when turned on without a game cartridge inserted?": Growing up in the 80s and 90s in the UK, it was "common knowledge" amongst my ...

According to the GBdevwiki: 0000-1FFF - RAM Enable (Write Only) Before external RAM can be read or written, it must be enabled by writing to this address space. It is recommended to disable ...

Where in the memory map ($0000-$ffff) does the Gameboy address the memory of these accessories? (for example, the battery or the Gameboy Printer). Is this something I should implement in an emulator?

When a Nintendo Game Boy is turned on, it displays a logo read from the cartridge (looking like this) before starting the game. What does it display if there's no cartridge inserted from which to read ...

According to Gameboy [sic] Development Wiki page The Cartridge Header, locations 0x104 through 0x133 in the cartridge contain a bitmap of the Nintendo logo that's displayed when the Game Boy is turned ...

When installing an old version of Windows, there is a step about application start tuning: This is not about the PREFETCH folder, since this feature appeared in Windows XP. Question: Does anyone ...

I'm writing a Game Boy emulator, but I don't completely understand how its memory mapping works. Here is what I (think) I know (and don't know). The CPU can address up to 0x10000 memory locations ...