Questions tagged [hardware]

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

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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, ...
25
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5answers
5k 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, ...
5
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1answer
241 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 ...
3
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1answer
134 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 ...
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
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7answers
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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 ...
8
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2answers
247 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 ...
-1
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1answer
106 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 ...
2
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1answer
115 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 ...
8
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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 ...
5
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2answers
203 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 ...
6
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2answers
535 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
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1answer
303 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. ...
1
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1answer
64 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 ...
3
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2answers
176 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 ...
2
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4answers
975 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 ...
2
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1answer
121 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 ...
29
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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
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1answer
460 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 ...
2
votes
1answer
93 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 ...
8
votes
1answer
968 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 ...
10
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1answer
596 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 ...
11
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1answer
544 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 ...
1
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4answers
116 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, ...
5
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1answer
204 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 ...
8
votes
2answers
230 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 ...
-5
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1answer
195 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 ...
16
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4answers
5k views

Why are old computers so vulnerable to temperature changes and moisture?

Interesting discussion by someone thinking of procuring a PDP-11/34, though having difficulty finding suitable space for it: https://www.reddit.com/r/retrobattlestations/comments/dztvci/...
4
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3answers
442 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,...
10
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2answers
1k views

Did any 360-compatible machine implement registers in core?

In the early days of transistors, when they cost on the order of a dollar each, it was possible to implement CPU registers with magnetic cores (the technology used for main memory at the time) instead ...
6
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4answers
430 views

Were there any games/software that used a resolution or resolution-mode higher than what was advertised available on the machine?

Were there any games/software that used a resolution or resolution-mode higher than what was advertised available on the machine ? On home / personal computers between anytime - 1984 . Without ...
1
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3answers
305 views

Were there any games/software that used memory beyond what was advertised available to BASIC on the machine?

Were there any games/software that used memory beyond what was advertised as available to BASIC on the machine ? On home / personal computers any time before 1984 . Without needing to plug in any ...
12
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3answers
1k views

Getting data from Seagate ST-238R drive

Hello: I have an old Seagate ST-238R drive. I'm the original owner and it stopped working in the early-90s when I foolishly deleted system files to make room for a football game. (I was 12 at the time)...
8
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3answers
1k views

How to implement bus sharing / DMA on a 6502 system

Was it possible for NMOS based 6502 system operate in the following fashion: while 6502 is not touching the bus one custom chip sets up memory read op, then two chips read the data off the bus at the ...
3
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0answers
293 views

What is the cause of Trent's circuit board strategy? [closed]

For those of you who are unaware, professional speedrunner Trent Hall discovered a now banned strategy in Goldeneye 007. This strategy (called Trent's Circuit Board Strategy) consisted of plugging a ...
1
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1answer
294 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 ...
20
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3answers
2k views

What does it take to recreate microchips like 68000 and 6502 in their original process nodes nowadays?

I am trying to figure out what type of machines could be used to reconstruct these chips nowadays. It doesn't need to use exactly the same machines used to build them, it's just that the product ...
5
votes
0answers
87 views

IBM terminal schematics

I'm searching for the electronics schematics for IBM terminals 3477 and 3486. I've already googled for it without success. I've to mend this hw and the power side seems ok but doesn't function, so I ...
3
votes
1answer
142 views

Did the IBM Game Control Adapter have I/O port aliases?

I was taking a look at the logic diagram in the manual for the original IBM game port adapter card: In the upper-left corner of the schematic, there is the circuitry responsible for decoding the I/O ...
5
votes
1answer
172 views

How did this coordinate capture peripheral work? [duplicate]

From an 80s Royal Air Force recruitment video, a peripheral is shown and it is used to capture coordinates off a map, onto a computer, for the flight plan to be written on a casette, for loading on ...
12
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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 ...
39
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4answers
7k views

When did computers stop checking memory on boot?

I remember my old 8088 used to do this (640K OK) but can't remember seeing anything like this since. Does this still happen and it's just not visible? If not, when did it stop, and why? (Imagining ...
4
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4answers
327 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) ...
34
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3answers
3k views

Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?

In short, 3 µm looks like it was the "standard" process size at the time, and it was available to Commodore before the chips were designed. Therefore it looks like using the larger 5 to 7 µm process ...
10
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2answers
1k views

Small RAM 4 KB on the early Apple II?

Most of the reference material for the Apple II that I have seen refers to the 4116 RAM chip which held 16x1 kbit. This provided 16, 32 or 48 KB in banks of 8 chips. The Apple II motherboard layout ...
7
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1answer
238 views

Digital PCB Plans for Retro Computers

I use software like Fritzing or Autodesk EAGLE to draw my Raspberry Pi or Arduino projects and was wondering if there is a source for PCB plans of for example an Amiga 500 in a format readable for ...
11
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3answers
484 views

What are the Ultra-Highres registers in ECS and AGA for?

The Amiga custom chip set, in its ECS and AGA versions, seems to contain some registers for what is called an "Ultra-HighRes/DUAL" mode: DFF078 SPRHDAT W Ext. logic UHRES sprite pointer and ...
1
vote
3answers
257 views

When was Tantalum first used in computing?

I know that nowadays Tantalum is very common in computer components, specifically capacitors, due to its desirable electrical properties. I'm curious when it was first used specifically in the ...
4
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2answers
302 views

Reference material for building a DIY Stack Computer from Logic Gates

I've been following Ben Eater's series of videos about designing a small computer from discrete logic gates, I'm curious if there is a similar tutorial/book/reference for building a stack computer. I ...
12
votes
1answer
337 views

How did restarts resolve parity errors triggered by broken core-rope wires?

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 ...