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I'm writing a Z80 emulator in Swift for Mac OS and I have got as far as implementing the 16 bit pop instruction. The documentation I have found (i.e. The Z80 CPU User manual UM008011-0816 and also ...
JeremyP's user avatar
  • 11.7k
25 votes
4 answers
5k views

Why does MP3 audio decoding overwhelm retro CPU's?

Many retrocomputers from the late 80s and early 90s had audio DAC hardware support. This includes the Amiga, Classic Macintosh, and PC's with SoundBlaster add-on cards. Despite the fact that the MP3 ...
Brian H's user avatar
  • 60.8k
20 votes
5 answers
2k views

What other computers used this floating-point format?

I have discovered that the DEC PDP-10 used a floating-point format that differed from IEEE-754 in an interesting way. IEEE-754 is like sign-magnitude representation. The only difference between a ...
robert bristow-johnson's user avatar
11 votes
3 answers
1k views

Was the PDP-11 coroutine instruction actually used?

In a typical description of the coroutine mechanism it usually mentioned that the PDP-11 instruction set provided a way to effect the coroutine switch by a single instruction, namely JSR PC,@(SP)+. ...
Leo B.'s user avatar
  • 19.2k
50 votes
3 answers
8k views

Why did the PDP-11 include a JMP instruction?

The PDP-11's program counter was addressable in two ways: as a general purpose register or as a memory location. Still, the PDP-11's instruction set included separate instructions for moving a new ...
Omar and Lorraine's user avatar
17 votes
3 answers
2k views

When was network byte order decided?

TCP/IP has some binary header fields which are affected by byte order, so defines 'network byte order' to settle the issue, specifically defines it as big-endian. When was this decided? The earliest ...
rwallace's user avatar
  • 61.3k
14 votes
1 answer
1k views

How did Apple's 'CYA' chip function to "Control Your Apple"?

Unlike the original Apple ][, the Apple IIGS was built from highly-integrated custom chips. Among these were the Mega II and the CYA (which, apparently stands for "Control Your Apple"). From what I ...
Brian H's user avatar
  • 60.8k
5 votes
1 answer
494 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?
Neb's user avatar
  • 51
8 votes
3 answers
724 views

Connectors for green screen versus color monitors

Consider a pair of early 14" CRT monitors, one green screen 80x25 text, one color 640x480 graphics. It seems reasonable to conjecture that both could have the same resolution; at least if you suppose ...
rwallace's user avatar
  • 61.3k
16 votes
4 answers
2k views

Computers with integrated monitor (all-in-one form factor)

The Commodore PET had an all-in-one form factor where the monitor was fused into the rest of the computer, making a single unit, not dissimilar to some early terminals like the VT100. This is ...
rwallace's user avatar
  • 61.3k
11 votes
1 answer
907 views

On the Z80, how can we use LD instead of JR?

The Galaksija ROM disassembly has a link to "A tutorial on how to use "ld" instructions instead of "jr" and save a few bytes in the process." My question is how does this work! It can see at l038ch ...
Omar and Lorraine's user avatar
17 votes
2 answers
2k views

How did the Trap65 work?

The Wikipedia page on the MOS 6502 mentions a hardware device called the Trap65 which apparently sat between the 6502 and its socket to trap any undocumented opcodes. The wiki page has the usual ...
Omar and Lorraine's user avatar
18 votes
4 answers
4k views

What was the first CPU with exposed pipeline?

Quoting from Programming for Performance exercise: early versions of the MIPS processor had an "exposed pipeline" (that is, the assembly language programmer needed to know the latencies of ...
Leo B.'s user avatar
  • 19.2k
15 votes
2 answers
1k views

What were the 9 VAC pins used for on the Commodore 64 User Port?

I read that pins 10 and 11 are the 9V AC +/- pins on the Commodore 64 User Port. Pin 10 is the + phase while pin 11 is the - phase. I realize the User Port wasn't as versatile as the Expansion Port (...
cbmeeks's user avatar
  • 8,531
8 votes
0 answers
252 views

Gamepad triggers main menu in Fuse SDL [closed]

I'm trying to set up a gamepad to work with Fuse on Ubuntu. No matter which type of joystick I try to emulate (including None), pressing button #2 (or B in the Sega naming) opens the main SDL menu. ...
Sergei Morozov's user avatar
10 votes
2 answers
4k views

Were any unlicensed games released for the Nintendo 64?

There haven't been many unlicensed games released for Nintendo consoles, partly due to the fact that Nintendo has locked down their development hardware and software. The most famous of Nintendo's ...
JAL's user avatar
  • 9,520
11 votes
2 answers
564 views

What happens when a floppy track contains multiple sync words?

This question is specifically aimed to the Amiga hardware. Let's assume a floppy track is read via DMA using sync word to trigger the start. Let's also assume the track contains the sync word ...
Valentino Miazzo's user avatar
18 votes
4 answers
3k views

What graphical effects can be created by changing the VIC-II settings?

I read in this answer that one could create graphics effects outside the usual specifications of the hardware by changing the settings of the machine's VIC-II at specific cycles during the video ...
wizzwizz4's user avatar
  • 18.6k
32 votes
5 answers
5k views

Does every retrocomputer and console with NTSC composite output have 'artifact color' ability?

Artifact color is heavily associated with the Apple ][, since that is the only method the machine had to produce a color display. I was looking at the fantastic demo for IBM PC + CGA, 8088MPH, and I ...
Brian H's user avatar
  • 60.8k
14 votes
1 answer
4k views

What is the relationship between the Ricoh 2A03 and the MOS 6502?

The Ricoh 2A03 (and the 2A07) is the CPU in the well-known Nintendo Entertainment System. Apparently, the die is very similar indeed, as the slides in this video suggest https://www.youtube.com/watch?...
Omar and Lorraine's user avatar
20 votes
1 answer
989 views

When was the relocatable object module invented?

During the time when programming was done in machine codes, there was no need for object modules; it just wouldn't make sense. People would write the whole program they needed to run in "zeroes and ...
Leo B.'s user avatar
  • 19.2k
8 votes
0 answers
400 views

Who and how worked on games in 80's? [closed]

As a developer in a team, I am used to some techniques and workflow, like using git, issue trackers, linters, common ways to discuss the structure of the code, the ways to debug and refactor code. I ...
Sergei Basharov's user avatar
31 votes
9 answers
13k views

NES cartridge ROM emulation with Arduino or Pi?

I'm looking to buy or make an NES cartridge that can be controlled by a microcontroller or small computer like the Raspberry Pi. I don't want to gut an NES cart and put an NES emulator inside it (as ...
Lucas Walter's user avatar
39 votes
5 answers
6k views

Why do programmable sound generators like SID include a noise generator?

In layman's terms, please explain the reason that all the popular PSG's used in 1980s computers and game consoles provided an additional channel to generate programmable "noise". How was this "noise" ...
Brian H's user avatar
  • 60.8k
19 votes
2 answers
2k views

First computer emulator in Windows

I released my ZX Spectrum emulation Wspecem, and GPL sources first time publicly in the Internet at large, the 15th May 1996, for Windows 95. I am quite sure it was the first ZX Spectrum emulation ...
Rui F Ribeiro's user avatar
13 votes
2 answers
1k views

NES repair - blue screen

I have an NES that was giving me a blinking red light when powering up. I had chalked this up to the 72-pin connector and set about cleaning it. After cleaning the connector and all games, the problem ...
DanBig's user avatar
  • 231
23 votes
6 answers
4k views

What was the first computer to support Arabic writing?

Looking at early microcomputers, all of them have support for something resembling ASCII, occasionally a few letters with accents and things were included also. And occasionally another alphabet such ...
Omar and Lorraine's user avatar
17 votes
5 answers
3k views

What was the first mass-market, 16-bit microcomputer system?

To qualify what I mean by "16-bit microcomputer system", I am talking about a system that has not only a 16-bit (or 32-bit) microprocessor CPU, but also a 16-bit wide external data bus connected to ...
Brian H's user avatar
  • 60.8k
13 votes
3 answers
2k views

Acorn Electron to VGA/HDMI?

I am aware that there are answers regarding this but they do not seem to answer it for me. A few years back I got a Acorn Electron and it works using the arial for video fine, but I would like to ...
Antony's user avatar
  • 131
18 votes
3 answers
7k views

Adjusting focus for old CRT monitors

I have an old Atari SC1224 CRT which has badly lost focus over the years. After taking the cover off, I can see various focus controls that can be adjusted by screwdriver. Question: is there a ...
jamesfmackenzie's user avatar
8 votes
1 answer
2k views

z80 CPU User Manual AND P/V Flag

I'm writing an emulator for the z80 CPU using the "z80 CPU User Manual" from zilog.com as reference. When I got into the AND operator I got confused. In the Condition Bits Affected is declared "P/V ...
h0m3's user avatar
  • 155
4 votes
1 answer
256 views

Include c files using z88dk

I want to split a program developed in c using z88dk in several .c files and I do not know how. I have these files: test.c: The main file with the "main" method. test2.c: An auxiliar file with the "...
Duefectu's user avatar
  • 231
7 votes
1 answer
358 views

How do I use IBM Filing Assistant on DOSBox?

I would like to get specific step by step instructions on how to use an old word processor called IBM Filing Assistant on DOSBox to be able to access old 1980s documents. How to use DOSBox other than ...
Ron 's user avatar
  • 103
10 votes
1 answer
439 views

RS232 Tape Recorder Emulator?

I need to interface between an older system that uses an RS232 port for reading/writing to a tape and a more modern computer that can manipulate the data and send it back. Is there a software+hardware ...
Zeda's user avatar
  • 203
6 votes
1 answer
2k views

What pins on the PS2 AV out port are the audio pins?

I'm trying to get some LEDs to be synced with sound. I'm trying to find the pins for the left and right audio on a fat PS2 motherboard. All I can seem to find is a pin with a solid 10v and 2 pins that ...
Justin's user avatar
  • 645
23 votes
2 answers
4k views

What are the "Screen Holes" in Apple II graphics?

I've read the term screen holes many times in the context of Apple II graphics. From what I understand, it has something to do with the interleaving storage of graphics (or was it text) and that some ...
cbmeeks's user avatar
  • 8,531
12 votes
3 answers
3k views

What is the name of the back arrow key on C64 keyboard?

What is the name of the back arrow key on top left corner of the C64 Keyboard? Is it escape or back? Also I don't recall using this key. What was the intended usage of it?
wizofwor's user avatar
  • 2,778
12 votes
4 answers
6k views

Amiga-looking keyboard for PC

I would like to use an Amiga-looking keyboard on my PC. (I prefer not to use my old original A2000 keyboard with an adapter, partly because it lacks many keys present on modern 105-key keyboards, and ...
dr_'s user avatar
  • 348
17 votes
3 answers
1k views

Apple II: DOS 3.3 Virus?

Does anyone know the source of this Apple II DOS 3.3 virus that infected my disks back in the 1990's? I got it from a public domain disk collection that was given to me by a friend, called the ...
Dale Mahalko's user avatar
  • 3,649
68 votes
12 answers
19k views

Did Apple not originally allow anyone to develop software for the Macintosh?

This probably nearly belongs on Skeptics.SE but here goes. Within the last few years I've become an Apple convert for the most part, which occasionally brings me into (usually) good natured conflict ...
Tom Kidd's user avatar
  • 863
12 votes
1 answer
888 views

Did the Apple ][ ever ship with the Autostart ROM

Did the Apple ][ ever ship with an autostart ROM from the factory or were they all the older ROM with Trace/Step? My guess would be that once the ][+ started shipping then new Apple ][ production (...
PeterI's user avatar
  • 5,307
5 votes
2 answers
986 views

What does the blinking of the cpu address bus actually means?

I'm currently running NOP on a Z80A cpu. All it does it flash some led, I expected it to flash 1 by 1. The led are place from address 16-0
user142208's user avatar
9 votes
2 answers
2k views

Was it Microsoft that started the war between Application and OS vendors?

I think there is a long history of application vendors going to great lengths to complain or litigate against Operating System vendors to compete fairly. Specifically, I am talking about "fairness" ...
Brian H's user avatar
  • 60.8k
5 votes
1 answer
148 views

Where are program datas stored on Windows Mobile 5.0?

I am probably a decade late with this question, but anyway. I digged out a PDA with Windows Mobile 5, and installed SpaceTime Mathematics on it. It is a 30-day trial (and you can't purchase the ...
Neinstein's user avatar
  • 151
12 votes
1 answer
4k views

Which C64 games support two buttons?

CIA 6526 chip used in Commodore 64 is capable of controlling two separate joystick buttons. But the second button should be connected through paddle pot input. This option was not popular till the ...
wizofwor's user avatar
  • 2,778
33 votes
6 answers
32k views

Windows 98 with 2GB of RAM

I have assembled a retro-gaming PC out of an old Shuttle SN45G with a Windows 98/Windows XP dual boot. The motherboard can handle 2GB of RAM, but apparently Windows 98 can only handle 1 GiB. Windows ...
Informancien's user avatar
  • 2,657
10 votes
2 answers
513 views

Order of powering down Atari ST and hard drive?

I am wondering if the order is important, which do I turn off first? The Atari ST computer or the external hard drive attached to it? It is on an SCSI adapter.
Douglas's user avatar
  • 103
10 votes
2 answers
594 views

What operating systems allowed arbitrarily-sized disk blocks?

According to my limited experience with IBM clone mainframes, and as far as I can remember, at least in one OS the permanent storage disk space was allocated to users (and the scratch space — to ...
Leo B.'s user avatar
  • 19.2k
12 votes
2 answers
3k views

Documentation on Windows Explorer Shell Command Files

Windows Explorer Shell Command Files are a feature added to Windows with Internet Explorer 4 (95 / NT 4). They were used in the now-defunct Quick Launch bar to show the desktop, open IE4's Channels ...
wizzwizz4's user avatar
  • 18.6k
2 votes
1 answer
2k views

What systems used hard sectored floppy disks?

Which computer systems used hard sector indexing of floppy disks? Background: On 5 1/4" and 8" disks there is a hole punched into the disk used for optical timing to locate the start of sectors. ...
Dale Mahalko's user avatar
  • 3,649

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