All Questions

32
votes
3answers
3k views

Reconditioning and cleaning old Nintendo (and other) game cartridges

I used to blow the dust out of the cartridges but I heard that can actually damage the cartridge or the system itself. I am looking for the proper way to clean old Nintendo game cartridges (such as ...
18
votes
4answers
3k views

Z8410 DMA chip as GPU?

There are basically two ways to design a 2D graphics system: Provide lots of hardware support in the form of tiles, hardware scrolling and sprites, to put together each frame on the fly from a small ...
14
votes
4answers
797 views

Retrocomputing Software Development Process/Methodologies

This is a test question based on this meta post. If the question can be reworded to be more on-topic, please feel free to suggest improvements. This is an open ended question about software ...
32
votes
3answers
4k views

What modification is required from a PC floppy for use in Amiga?

Around the end of the time of Amiga popularity, obtaining a replacement Amiga floppy drive was a nuisance, while PC drives were ubiquitous and cheap. One could install a PC drive in Amiga after ...
68
votes
8answers
8k views

What key factor led to the sudden commercial success of MS Windows with v3.0?

Microsoft Windows was originally introduced in 1985, ostensibly to compete with the Apple Macintosh, and other computers shipping with graphical shells by that time. However, early versions of Windows ...
8
votes
5answers
840 views

How to patch binaries in DOS?

In the late MS-DOS era, what were the state of the art software tools for reverse engineering and patching binaries, i.e. .exe and .com files? A simple list of the tools that were "state of the art", ...
61
votes
8answers
15k views

Why do C to Z80 compilers produce poor code?

When reading some other questions about compiling C for the Z80, How much benefit should be expected on a more advanced compiler for z80/r800 based computers? Native C compiler for Sinclair ZX ...
50
votes
3answers
5k views

How does the LOADALL instruction on the 80286 work?

This undocumented instruction existed in the 80286 and, I believe, the 80386. I think it was added while debugging the chip, so the engineers could quickly put the processor into any state and test it ...
54
votes
6answers
14k views

How were the first ZX Spectrum games written?

Being a child of the 80s I loved my ZX Spectrum, did my best to learn BASIC but I felt like the games I was playing (Jetpac, Dizzy, Renegade etc) were perhaps not written using BASIC. I wondered: how ...
46
votes
5answers
9k views

Which Linux or BSD distributions do still support i386, i486 or i586 CPUs?

Unfortunately Debian kicked out Pentium 1 (i586) CPU support from its 32-bit PC port (named i386 for historic circumstances) for its next stable release Debian 9 Stretch. (Then again they complain ...
78
votes
4answers
7k views

Were there 8086 coprocessors other than the 8087?

The 8087 math coprocessor for the 8086 (and descendants) nominally added floating point and transcendental (trigonometric and logarithmic) instructions to the 8086. Contrary to naive expectations, the ...
36
votes
1answer
2k views

What precautions to take when powering on old computer for the first time in years

I have a Commodore 128D that hasn't been powered in about 15 years. I want to begin using it again. It has been stored in cool dry places like attached garages, in a cardboard box. I hope this ...
19
votes
2answers
3k views

Wiring a Zilog Z80

I've recently got hold of an old Zilog Z80 microprocessor and I know how to clock and test it. I do not however know how to connect RAM, I/O ports, control switches (for programming instructions into ...
27
votes
5answers
2k 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 ...
42
votes
8answers
9k views

How long will floppy disks maintain data integrity?

This was on CNN today: The U.S. is still using floppy disks to run its nuclear program Which led me to read through this article: Think the floppy disk is dead? Think again! Here’s why it still ...
22
votes
4answers
6k views

What exactly is a cycle-accurate emulator?

Emulators such as Higan are cycle-accurate and thus have full compatibility with all existing software. In a 2011 Ars Technica article, much was said about cycle accuracy and how it preserves games by ...
16
votes
2answers
2k views

The start of x86: Intel 8080 vs Intel 8086?

Why is it said that all modern Intel processors of the x86 family are said to descent from the Intel 8086 and not the Intel 8080? From the Wikipedia article on the Intel 8086, The 8086 gave rise to ...
10
votes
2answers
866 views

How does the 6502 implement its branch instructions?

The 6502's decode ROM takes an input which tells it when to start the next instruction. In the case of something like an INX or LDA #7F, it is obvious that once the output from the ALU has been ...
20
votes
1answer
653 views

When does the VIC-II read the sprite data?

This question is about the Commodore 64 and its graphics chip, the VIC-II. Imagine that on a particular scanline, the VIC-II needs to fetch 40 bytes (the background tiles) and since it's a badline ...
10
votes
2answers
825 views

How did the IBM PC handle multiple physical devices serving memory at the same physical address?

I'm trying to figure out how the IBM 5150 PC handled the case where multiple physical devices (memory chips) were mapped to the same address within the 8088's physical address space. The closest I've ...
37
votes
2answers
6k views

How did the Z80 instruction set differ from the 8080?

The Zilog Z80 microprocessor, known for its use in the ZX Spectrum, was designed to be a backwards-compatible extension to the Intel 8080 processor. It introduced several new instructions to the 8080'...
60
votes
2answers
7k views

Why did Unix use slash as the directory separator?

The Unix designers came from the GE/MIT Multics project, and Multics inspired some Unix features. In particular, Multics has a hierarchical filesystem, and so does Unix. On Multics, pathnames were of ...
39
votes
2answers
5k views

What is between the sectors of floppy disks?

I've found this page which has an informative description of how sectors were encoded on floppy disks: http://nerdlypleasures.blogspot.com.au/2015/11/ibm-pc-floppy-disks-deeper-look-at-disk.html Do ...
75
votes
18answers
15k views

Why was BASIC built into so many operating systems?

There are a lot of retro-computers with BASIC as an integral part of the operating system. The IBM 5100 was one of the first computers with a separate memory space for BASIC, followed by the Commodore ...
58
votes
5answers
13k views

Is it safe to turn on a 40-year old TRS-80?

My father is a retired programmer. When I was in high school in the late 1970s, he purchased a TRS-80 model 1 (on which I learned to program in BASIC). At some point in the early 1980s it, together ...
21
votes
2answers
5k views

Which original retrocomputer OS's are still maintained and updated today, for original hardware?

I would like to know which original Operating Systems that run on retrocomputers are still being actively maintained and updated. This only applies to retrocomputer OS's that may still be used on ...
51
votes
12answers
11k views

What early home computers have more than one CPU, where both could be used by the programmer? [closed]

I am interested to know if any computers that are on-topic for this site had more than one CPU, where this plurality could be leveraged by a programmer. Some cases I don't so much care about: The ...
37
votes
11answers
5k views

What is the oldest computer capable of running a modern version of Linux?

A bit of a trivia question: What is the oldest hardware capable of running a modern Linux-based operating system ? By this I mean being capable of running a fairly recent Linux kernel, in some form. ...
39
votes
5answers
15k views

Why did CPU designers in the 70s prioritize reducing pin count?

A lot of 70s era microprocessors were packaged in DIP packages with 40 pins. This was a reasonably good fit for 8-bit processors: 16 address lines, 8 data lines, 2 power and clock are all absolutely ...
37
votes
4answers
17k views

Commodore 64 to modern TV

I've been thinking about getting a Commodore 64 machine. However, I realise there's obviously no video cables I have that will work. But when I looked online there are many people using S-Video to VGA ...
33
votes
4answers
7k views

What determines the color of every 8th pixel on the Apple II?

On the Apple II there's an interesting way to add a little color to the bitmap, since the high bit select the palette used for the three-and-a-half pixels represented by the byte. Like this: 0: Black,...
53
votes
3answers
10k views

Why did DOS use dollar-terminated strings?

According to a few tutorials I am seeing, DOS used dollar-terminated strings to write to the terminal. This seems to also be documented here on INT 21H. AH = 09h - WRITE STRING TO STANDARD OUTPUT ...
32
votes
8answers
9k views

Why were floppy disks invented after hard disks?

For those of us who grew up with personal computers in the 1970's or 1980's, the experience was a very gradual migration from floppy disks to hard disks as the primary persistent storage. So, based on ...
28
votes
8answers
6k 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 ...
30
votes
7answers
4k views

Is it legal to download ROM images from shared or internet archives?

Is it generally legal to download older ROM images of commercial software and games for non-commercial use in a retro computing system (emulated or otherwise)? (Note that this question implies no ...
21
votes
2answers
565 views

How do I use shadowed memory to render Super Hi-Res quickly?

The Apple IIgs video memory is controlled by the 1MHz Mega II chip, so directly accessing the Super Hi-Res page in bank $E1 is slower than accessing other memory. How can I render in "fast" memory, ...
23
votes
9answers
5k views

Graphics chips in 1980

Suppose you were trying to build a computer with a color graphics display in 1980, you have limited engineering resources and time to market is critical, so you want to get as many of the parts off ...
21
votes
3answers
3k views

Why did Pokémon Red have so many overflow bugs?

(This question also applies to other Game Boy games, but Pokémon seems to be one of the best-documented.) Pokémon Red & Blue (Red & Green in Japan) is a pair of Game Boy games about capturing ...
15
votes
3answers
5k views

How can MS-DOS be installed on VirtualBox?

As part of the MSDN subscription I just got, I can download MS-DOS 6.22 (wow indeed). I want to install it to a VirtualBox VM so I can try old games and viruses (due to viruses, I can't install it to ...
15
votes
3answers
971 views

Why did the Sinclair ZX-Spectrum use a membrane keyboard?

As a kid, I always had problems with the keyboard. Membrane was hard to come by and expensive. I did not have Kempston/Protec. So I had to play on the keyboard. I was using QAOPMN combination, and ...
11
votes
6answers
1k views

Z80 and video chip contending for random access

Back in the 8-bit days, I used 6502 computers, where the story about memory access was easy to understand. RAM chips of the late seventies and early eighties could do 2 MHz (or a bit more e.g. 2.6 in ...
26
votes
10answers
2k views

What were the applications of 5/6-bit serial port formats?

Traditional PC serial ports, based on members of the 8250/16550 UART families (or their clones within SuperIO chips) support some unusual serial data formats, specifically 5- and 6-bit data, and 1.5 ...
25
votes
4answers
657 views

How to get rid of yellowing in plastics?

I have some old electronics with white plastic that's starting to turn yellow. I know it's caused by flame retardants, UV rays, and so on. How can I restore my electronics to their former color?
24
votes
2answers
2k views

How did MS-DOS assign drive letters in the case of more than two floppy disk drives?

The IBM PC BIOS had provisions for up to four floppy disk drives, by virtue of returning the number of floppy disk drives in a two-bit field plus a none/some flag (allowing for reporting values of 0, ...
20
votes
2answers
394 views

Why was segment register value scaled by such a small factor of 16 on i8086?

In 8086 architecture memory is addressed by segment:offset scheme, where the 20-bit linear address is formed as address=segment*16+offset. This looks needlessly complicated and doesn't allow to ...
18
votes
2answers
1k 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 ...
16
votes
4answers
3k views

Why did the TI-99/4 have two databuses?

Wikipedia says on Russian page: Однако к 16-разрядной шине были подключены только 256 байт статической памяти и системное ПЗУ. Остальная память (ОЗУ) и периферийные устройства были 8-разрядными и ...
16
votes
5answers
964 views

Limiting factor on sprite sizes

Early consoles and home computers that were optimized for games, tended to provide sprites. From a game programmer's viewpoint, these were good to have. Of course, one always wanted more and larger ...
16
votes
2answers
1k views

What makes slot 7 of the Apple ][ unique from 1-6 and how was this used?

In the Apple II, there are three unique slots (depending on model): Slot 0 (on the ][ / ][+) which is typically used for language cards. "Aux" slots in the //e and IIgs, typically used for memory ...
14
votes
1answer
437 views

What is the prototype of the Eastern Bloc videoterminal Videoton 340?

Several decades ago, the Hungarian company "Videoton" manufactured a videoterminal for which I couldn't find a Western prototype. It likely existed, as the device had been assigned a "ES" number, ...

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