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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 ...
38
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
214 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 (...
8
votes
6answers
724 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
110 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 ...
7
votes
1answer
429 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
331 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 ...
16
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 ...
12
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
220 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, ...
3
votes
2answers
158 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 ...
37
votes
3answers
5k views

How did C64 games handle music during gameplay?

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 ...
4
votes
3answers
195 views

How does states, bus cycles and clock cycles differ in the M68000?

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 ...
4
votes
2answers
322 views

Is the Game Boy Sharp LR35902 object-compatible with the 8080/Z-80?

(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 ...
3
votes
2answers
217 views

How does Game Boy / Sharp LR35902 HRAM work?

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 ...
2
votes
1answer
267 views

Long variable names in MS BASIC

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 ...
44
votes
7answers
9k views

What was the rationale behind 36 bit computer architectures?

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?
3
votes
4answers
300 views

What determined the type of error dialog being shown in Windows 3.1?

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 ...
2
votes
1answer
194 views

Connecting Computer to GameCube Controller Port

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 ...
8
votes
1answer
193 views

String libraries for BASIC

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 ...
2
votes
2answers
155 views

Non-obvious compatibility of M1297 monitor

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 ...
35
votes
7answers
12k views

Why did computer video outputs go from digital to analog, then back to digital?

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....
74
votes
9answers
17k views

Why did modems have speakers?

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 ...
13
votes
5answers
5k views

Does switching on an old games console without a cartridge damage it?

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 ...
9
votes
2answers
2k views

On a Gameboy, what happens when attempting to read/write external RAM while RAM is disabled?

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 ...
1
vote
1answer
140 views

How does the Gameboy address external hardware?

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?
26
votes
3answers
9k views

What does a Nintendo Game Boy do when turned on without a game cartridge inserted?

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 ...
14
votes
4answers
1k views

Why is the unchangable Nintendo Game Boy logo in the cartridge?

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 ...
24
votes
2answers
2k views

What does Windows' “Tuning up Application Start” do?

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 ...
18
votes
3answers
3k views

How does the Gameboy's memory bank switching work?

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 ...
4
votes
1answer
126 views

ACA1221 cooling

I have an ACA1221 accelerator (not EC). The card is clocked at 28MHz and get's VERY hot. Even when running on default 17MHz the temperature can go as high as 65'C. Is there any way to use any of the ...
2
votes
1answer
181 views

Old SCSI controller won't boot on certain PC

I have an old Adaptec PCI SCSI controller from around 1995 (bios date, will get full model if needed). It's lived its life in an old pentium 133mhz pc from around 1995 as well. The controller is 50 ...
19
votes
3answers
3k views

What makes MOVEQ quicker than a normal MOVE in 68000 assembly?

I'm "re-learning" 68000 assembly language and came across the "MOVEQ" command that is labeled "MOVE QUICK". According to the NXP Programmers Reference Manual (reference below), the command MOVEQ (...
42
votes
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 ...
10
votes
5answers
2k views

What was the difference between a Games Console and a Home Computer?

In the world of home entertainment and video games, two terms that were commonly used to describe machines from the 1970s onward are "games console" and "home computer". Some devices appear to ...
19
votes
3answers
3k views

Term “console” in game consoles

Not sure if this exactly fits here, but I’m interested in the history of word “console” in game consoles and in computing in general. I can see at least two usages for the term, which at least ...
21
votes
7answers
7k views

Why is the Intel 8086 CPU called a 16-bit CPU?

Based on my understanding, the bitness of a CPU specifies how much memory it can address (which is determined by the size of the CPU's address bus I guess). For example: a 32-bit CPU can address 232 ...
1
vote
1answer
283 views

Why doesn't the Intel 8086 CPU use real memory addresses? [duplicate]

The address bus of the Intel 8086 CPU is 20-bits, and when you want to specify a memory address to read from or write to, you would form the memory address using a segment register and an offset ...
17
votes
8answers
4k views

Intel 8080-based home computers

I'd like to build an FPGA replica of a home computer based on the Intel 8080. I am not looking to design my own computer, since I would like to tap into an existing software base. Were there any ...
13
votes
7answers
4k views

Does the Intel 8085 CPU use real memory addresses?

The Intel 8086 CPU uses memory segmentation, which means that when, for example, you write the value 123 to the memory address 1001, the memory address 1001 will actually get converted first into ...
9
votes
1answer
188 views

SYNC and the 65CE02 instruction timing

From the Wikipedia's 65CE02 page: Internally, the pipeline of the 65CE02 was redesigned to reduce the number of cycles required to execute an instruction. The 65CE02 can recover faster from ...
5
votes
2answers
187 views

Dimensioned drawing of 64-pin SIMM?

I am looking for a dimensioned drawing of a 64-pin SIMM PCB like the ones used in the Macintosh II series for the ROM SIMM. I looked in Guide to the Macintosh Family Hardware and Designing Cards and ...
69
votes
3answers
13k views

What made Windows ME so crash-prone?

Many people remember this operating system as not exactly a walk in the park, namely that it could crash as early as during the installation phase or at unexpected times when the user wasn't doing ...
8
votes
3answers
925 views

Behavior of the zero and negative/sign flags on classic instruction sets

It seems to me that there's effectively two ways that the zero bit could work. Z is set iff the result of a computation is mathematically equal to 0. Z is set iff a bit pattern consisting entirely of ...
1
vote
0answers
115 views

Why is the order of the special characters on the keyboard like !@#$%^&*()? [duplicate]

The order wasn't easy for me to memorize. I would like to know if there is a historical story.
16
votes
1answer
3k views

How did the Game Boy Advance stretch Game Boy games to widescreen?

The original gameboy, GBP and GBC all had screen resolutions of 160x144[1] while the Game Boy Advanced had a resolution of 240x160[2] So how does the actual stretching occur? It seems pretty uniform, ...
-3
votes
1answer
141 views

Building a Sega Genesis Classic Portable - What kind of display? [closed]

I am trying to make a portable version of a Sega Genesis Classic. (See this example on Youtube.) I'm wondering what kind of display module I would need to solder to the board for this project.
2
votes
1answer
231 views

Connecting SCM Swapbox PCMCIA reader (ISA) to modern PC

Further to my previous question, I am wondering how best to connect an SCM Swapbox "SBI-D2P" (Classic X2) PCMCIA card reader to a modern PC (PCI/PCI Express/SATA/USB). I am aware there are USB PCMCIA ...
7
votes
1answer
215 views

WEGA operating system origins

I just recently stumbled across information about DDR minicomputer P8000 and its unixoid operating system WEGA. The website above as well as Wikipedia seem to claim some compatibility or even ...

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