Questions tagged [hardware]

For questions about the components of retro devices (computers, etc.)

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9
votes
2answers
283 views

Were expansion slots fundamentally incompatible with FCC regulations?

The Apple II provided the ability to connect to your TV (as opposed to purchasing a dedicated monitor). However, at that time, the FCC criterion for applying stringent RF emission limits was 'device ...
3
votes
2answers
175 views

What's the Motorola microprocessor with two sets of registers to avoid costly context switch?

I remember reading somewhere (maybe on Hacker News or Lobsters) that Motorola made a microprocessor some decades ago with two sets of registers. This means when handling an interrupt, it does not need ...
22
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5answers
3k views

DIY Project using 1970s 8-bit CPU, is it possible?

I've recently really wanted to try and design a computer system around a retro 8-bit CPU such as the Zilog Z80 or the Intel 8080, and I would appreciate some sanity checks! I was inspired by Ben Eater'...
2
votes
2answers
284 views

Why did extracodes fall out of favour?

Once you have an operating system that provides services callable from programs, you need to provide a way for programs to request those services. These days the general approach only requires a ...
10
votes
2answers
1k views

How did most fifth-generation consoles avoid wobbly graphics?

According to Why do 3D models on the PlayStation 1 “wobble” so much? the PlayStation had a problem with wobbly graphics because Filling a triangle involves visiting every pixel within it and ...
3
votes
1answer
203 views

How to set up a payphone phone network central office

I would like to setup a network of payphones inside my college as part of a retro phone systems / artistic interactive exhibit. I would like to be able to use the payphones to make calls inside the ...
7
votes
1answer
283 views

In the 1970s, had there been a way that a home computer using a TV as monitor could get FCC approval for Apple II style slots without cheating?

I’m reading the book “Atari Inc.: Business is Fun” by Curt Vendel and Marty Goldberg. (By the way, it’s a fun read, highly recommended.) It states that when the Atari engineers had been developing the ...
2
votes
0answers
178 views

What was the cost of the PS2 chip in the last PS3 to have it?

The PlayStation 2 provided backward compatibility with the PS1 by essentially incorporating an entire PS1 on a separate chip. It kept this arrangement permanently. The PS3 started off providing ...
5
votes
1answer
337 views

How much memory did the PlayStation development kit have?

The PlayStation 1 had two megabytes of main memory, one megabyte of video memory and half a megabyte of audio memory. Squeezing everything to fit into these limits was one of the big challenges of ...
11
votes
3answers
2k views

6502 reset pin: always needed on power on?

The 6502 pinout has a reset pin, which presumably would be used if a reset button is pressed on the machine containing the CPU. But the 6507 contains the same pin. The 6507 was designed at the ...
38
votes
6answers
9k views

Why did early arcade games use vertical displays?

Surprisingly many early arcade games, such as Pac-Man, Galaxian and Galaga, mounted their displays vertically, in portrait rather than landscape orientation. (From the perspective of the electronics, ...
8
votes
5answers
3k views

Did any RISC CPU ever take more than one clock cycle per instruction?

Classic RISC CPUs like ARM and MIPS basically offer the trade-off: simple instruction set, but instructions execute in one cycle for good overall performance. (It gets more complicated in later times, ...
6
votes
1answer
414 views

How did the Donkey Kong arcade hardware provide 128 sprites?

According to https://en.wikipedia.org/wiki/Donkey_Kong_(video_game) The Donkey Kong hardware has the memory capacity for displaying 128 foreground sprites at 16x16 pixels each and 256 background ...
20
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3answers
2k views

Why was it not possible to cost-reduce the Amiga 500?

According to 'Commodore: The Final Years' (whole trilogy highly recommended, BTW), page 129, 'Jeff Porter realized it would not be possible to significantly cost reduce the Amiga 500 to get it into ...
18
votes
7answers
3k views

Cost of unrestricted sprites

All the game consoles of the second through fourth generations, and several early home computers, had sprites, which were valuable though costly, e.g. the VIC-II spent 2/3 to 3/4 of its area on ...
3
votes
1answer
137 views

ABEL HDL: What was the purpose of the 'flag' keyword?

Some context first: ABEL (Advanced Boolean Equation Language) is an old hardware description language which has been mainly used in the 80/90s to program CPLDs. Unfortunately I have not found any ...
4
votes
2answers
196 views

Sam Coupé power supply heat

I have a Sam Coupé and the last time I turn it on, i noticed a smell of components overheating. After opening the power supply I came to the conclusion that is the resistance R1 (50ºc with IR ...
13
votes
4answers
1k views

Mind-Controller User Input from the late 90s

In the late 1990's, I recall that there was a piece of hardware being demonstrated in Best Buy that supposedly allowed you to control your computer via signals sent from your brain. How it worked is ...
11
votes
1answer
726 views

Can the BBC be programmed to a half-size mode 1 screen mode with 16 colours instead of 4?

Screen Mode 2 on the BBC micro is 160 x 256 with "16"* colours. This uses up 20Kb of memory. Horizontal-rectangular pixels ( 2 x squares each). 4 bits per pixel (0-15 values for 16 colours) Screen ...
26
votes
4answers
5k views

How did the BBC Micro stay cool?

The BBC Micro used the extended variant of the classic 'computer in keyboard' design; like the Apple II, the case went back far enough that you were encouraged to put the monitor on top of it. All ...
5
votes
2answers
210 views

Could monochrome systems produce better output for monitors than TV sets?

Many classic computers could optionally use a TV set as the display. At least in the early (pre-SCART) days, the TV would typically only have RF input, but if you were using a monitor, you could get a ...
-1
votes
1answer
110 views

Fan for old socket A Athlon cooler [closed]

I put together a retro gaming setup with a 2000ish spec (can post specs if required) and it's come together pretty nicely except the CPU fan is insanely shrill (it's a Coolermaster something). If I ...
4
votes
4answers
332 views

Are there standard DIN pinouts for cassette and video ports on early Japanese 8-bit computers?

I have several different Japanese 8-bit computers, and they use similar DIN connectors for video and cassette I/O: Composite video: 180° 5-pin DIN: Fujitsu FM-7, NEC PC-8001mkII Color TTL (digital) ...
8
votes
3answers
2k views

Did multiplexed address/data lines make memory access slower?

Looking at the pinout of e.g. the 8088, it multiplexes the data lines onto eight of the address lines; presumably the designers judged that being able to squeeze the chip into a 40-pin package, would ...
2
votes
1answer
118 views

Vic-20 tape I/O dependence on CPU speed?

As I understand it, the Vic-20 reads and writes the cassette deck by the low-tech expedient of just using the CPU to bit-bang a one-bit serial line. This presumably means that for a given code ...
2
votes
1answer
122 views

Did the ZX80 RAM pack pass the expansion bus through?

The ZX80 only came with 1K of RAM, which had to be shared between program and screen memory, so many customers bought the Sinclair 16K RAM pack, which plugged into the expansion bus (the edge ...
18
votes
1answer
687 views

Any difference between a VIC-1541 and a C64-1541?

I have both a beige VIC-20 styled VIC-1541 disk drive and the later brown C64 1541 drive. Is there a difference between them (besides how they look)?
6
votes
2answers
551 views

What was the title safe area on PAL TV sets?

Computers that used TV sets for display, needed to worry about the title safe area. By consensus, on NTSC sets, it was 200 scan lines, or 192 if you wanted to play it really safe. What was the ...
2
votes
1answer
333 views

How much did it cost to develop the Z80 CPU?

How much did it cost, in dollars at the time, to develop the Zilog Z80 CPU? According to Wikipedia, The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. ...
3
votes
2answers
185 views

What does the ZX81 ULA use A14 and A15 for?

As I understand it, the ZX81 video system, which resides in the ULA like all the rest of the machine-specific logic, works by using the CPU as an address generator: during active scan line, it lets ...
1
vote
1answer
67 views

How does the ZX81 ULA generate a full ROM read address?

On the ZX81, when the ULA that functions as the video chip is generating display output, it takes the character cell byte (that the CPU was tricked into fetching as an opcode) and combines it with an ...
2
votes
4answers
979 views

What is the analog component of sound output in an early home computer? [closed]

For a concrete example, take the Vic-20. It is well documented that the 6560/6561 Video Interface Chip was also responsible for sound generation, having three voices and one noise generator. The ...
29
votes
3answers
5k views

Why did the ZX80 CPU run at only 3.25 MHz?

The Sinclair ZX80 used a Z80A running at 3.25 MHz. But this chip was rated for 4 MHz. Why was it run below rated speed? Apparently the master clock in the machine ran at 6.5 MHz, so the CPU clock ran ...
6
votes
1answer
471 views

How did the ZX80 RAM pack use DRAM?

The Sinclair ZX80 was the most popular personal computer in Britain at the beginning of the 1980s, due to its low price which was enabled by extreme minimalism; it consisted of not much more than a ...
11
votes
1answer
561 views

What is the history of the Intel 8275 video controller?

The highly popular at the time build-it-yourself home computer Radio 86RK, designed in the Soviet Union, contained a rather mysterious video controller chip KR580VG75. It had a high end, feature rich ...
8
votes
1answer
979 views

Were single-sided floppy drives really more tolerant of rough handling?

The Osborne 1 was a luggable computer that contained a pair of 5.25-inch floppy drives. According to https://en.wikipedia.org/wiki/Osborne_1 Adam Osborne decided to use single-sided disk drives out ...
2
votes
1answer
95 views

How long would a 41256 take to do 4 accesses in fast page mode?

I have been surprised at how little use eighties computers made of fast page mode access to RAM. (A notable exception being the Sinclair Spectrum, which used it to get the necessary bandwidth to video ...
10
votes
1answer
603 views

How many cards could you put on an S-100 bus?

The S-100 bus was something of an industry standard in the 1970s, for 8080 and Z80 computers built on a backplane design. It was invented with the Altair 8800, which apparently provided 16 or 18 ...
1
vote
4answers
122 views

Will any modern EEPROM programmer work with the IP3604/КР556РТ5?

Just to say I'm completely new to the world of PROM and I'm a bit bewildered. My ultimate aim is to be able to program these Russian 4k bipolar PROM chips, which are the equivalent of Epson IP3604, ...
8
votes
2answers
234 views

When was the first 3 state IC produced?

This was prompted by a question on the electronics site (which was asking why only an open collector variant of a particularly old part existed and how it could be part of a data bus). This was a ...
23
votes
5answers
2k views

Were there any LSI-11 like home computers outside of Russia?

In my childhood I had one of these: https://en.wikipedia.org/wiki/Electronika_BK Note, that the CPU of this is based on LSI-11. This is rather surprising because PDP-11 took a room (I was lucky ...
31
votes
5answers
3k views

Which ports are which on this Soviet ZX Spectrum clone?

Today I got my (first) Soviet ZX Spectrum clone. The person who sold it to me had inherited it and had no idea how it worked. It seems to be a home-made clone, rather than a factory-built one. See ...
1
vote
1answer
297 views

Estimating contents of old printed circuit boards

I am sorry, if this is not a good place to ask, but is there any general rule of thumb about how much precious metals could you expect to get out from 197x(?) printed circuit boards, especially Soviet ...
5
votes
1answer
206 views

Finding replacement LEDs for Commodore gear?

Around 1984, Commodore transitioned from using round LED bulbs for power and drive indicators to rectangular ones. Some of these could be quite wide, like the ones pictured for a 1571 disk drive. They ...
29
votes
9answers
10k views

How did early x86 BIOS programmers manage to program full blown TUIs given very few bytes of ROM/EPROM?

I've always wondered how so much functionality and relative luxuries(CMOS Configuration Utilities. See: https://geekprank.com/bios/ for an example) included with most popular x86 BIOSes could be ...
3
votes
1answer
166 views

Osborne Turbomate IV Information?

Howdy Retro Computing Stack Exchange, I semi-recently came into possession of an Osborne Turbomate IV computer with an Ipex monitor and Brother dot matrix printer (along with original Osborne mouse ...
21
votes
3answers
4k 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 ...
4
votes
3answers
458 views

What was stored in memory that was “unavailable to BASIC”?

On home / personal computers (such as before 1984), a machine might be described as having 24k RAM, but only 18k of that available to BASIC. If the machine had BASIC and the OS (or BIOS) stored in ROM,...
12
votes
4answers
2k views

Amiga 500 OCS/ECS vs Mega Drive VDP

Superficially the Amiga 500 and Mega Drive are similar. Both run a Motorola 68000 CPU at similar clocks and both have dedicated hardware for sprite and other graphics operations. Comparing the arcade ...
-5
votes
1answer
201 views

Why did Western Digital name their drives “Caviar”? [closed]

I'm asking in Retrocomputing because the Caviar line of HDDs was released in the most recent era of retrocomputing. Does anyone know why they named the line "Caviar"? Why do they associate Sturgeons ...

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