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

5
votes
2answers
173 views

How to protect a ZX Spectrum mainboard from “ageing”?

I have some ZX Spectrums, and in some of them I observe a kind of "disintegration" process of the main board. The connectors break away etc. During the tests one of the boards burned out :(. How can ...
6
votes
0answers
163 views

How was the Intel 80486 debugged? [closed]

How was the Intel 80486 (from 1989) debugged? I'm assuming it was written in some HDL language, like Verilog. However, how was testing and debugging of the CPU carried out? Were there several steps ...
8
votes
1answer
312 views

How did the Commodore PET 80 column display work?

Some variants of the Commodore PET (e.g. the 8000 and 9000 series, as well as some other versions with an aftermarket add-on) produce an 80x25 character display. Their character set is fixed in ROM ...
23
votes
4answers
4k 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 ...
3
votes
2answers
217 views

When did the Macintosh start using four (or more) layer PCB's?

I'm assuming (but do not really know) that the original Macintosh used a two layer PCB. So my question is, when did the Macs start using more complicated boards with four (or more) layers? For ...
6
votes
2answers
2k views

Was the IBM 5100 ever used for codebreaking?

There's a rumor that there's something embedded in the IBM 5100 which makes it useful for codebreaking. What is the legitimacy of that claim?
3
votes
3answers
289 views

What was the first integrated PC compatible computer?

When IBM developed the PC, they famously chose a bunch of off-the-shelf components. Besides making the machine relatively easy to clone, another effect of this was it used a lot of chips and board ...
7
votes
4answers
659 views

Why the switch to “Mickey Mouse” (type C14) power cables?

Inspired by this question asking about "regular" power cables, I have been curious about (read: irritated by) the rise of "Mickey Mouse" power cables. Apparently they come from the same standards ...
1
vote
1answer
198 views

Physically emulate Gameboy cartridge using Raspberry Pi? [duplicate]

This is an extension to the question NES cartridge rom emulation with arduino or pi?, which asked whether it would be possible to physically emulate a NES cartridge using an Arduino/Raspberry Pi (RPi)....
25
votes
7answers
10k views

Why did computers use a power supply with a socket?

Most home electrical appliances use a fixed power cord and have a on/off switch near the front. I was in many government electronics labs and that cord and socket was not used i.e HP test equipment. ...
4
votes
0answers
151 views

Cost of Apple II switching power supply

Apple went to the trouble of designing a switching power supply at a time when they were still quite new and not widely used for consumer electronics, perhaps because Steve Jobs liked the aesthetics ...
1
vote
2answers
218 views

Conventional Hard Drive life-span [closed]

I have a bunch of hard drives. From 500 megabytes to a few gigabytes from years around 2000-2006. I was wondering if those are still readable or are dead. Should I hurry up finding an adapter and try ...
0
votes
2answers
175 views

Lead Free Solder in Pre-2006 Electronics

In 2006, the European Union passed the Restriction of Hazardous Substances Directive (RoHS) which pretty much restricted the use of traditional lead-tin solder. Is it the case that all consumer ...
8
votes
2answers
312 views

8086 pinout and address space limit

It is tempting to say - and I have said - that Intel made a mistake in the design of the 8086 and 8088, in going from 16 bit addresses to only 20 bits; if they had even shifted the segment registers ...
1
vote
1answer
78 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 ...
97
votes
4answers
18k views

It's now safe to turn off your computer

One thing I remember very well from my childhood is the screen you got at the end of a shutdown process ond old computers: I don't know if this was a Windows 95/98/2000/ME only thing but I wonder why ...
27
votes
5answers
5k views

Why do hard drives not use larger platter sizes anymore?

In reading a related question about floppy drive capacity, I thought to ask a question I've had for a long time. When I started programming, all PC hard drives used the 5¼" platter size. There were ...
6
votes
4answers
606 views

Why did common floppies never advance past 1.4 MB in size?

The chronology of some early floppy standards was: 80 kB, 160 kB, 360 kB, 720 kB, 1.2 MB, finally 1.44 MB. (There where less common sizes such as 250 kB, 800 kB,...
7
votes
1answer
200 views

VIC-II transistor count

I'm curious about the transistor count of the VIC-II, the video chip in the Commodore 64. According to http://visual6502.org/wiki/index.php?title=Chips_in_our_collection the Atari 2600 TIA chip has ...
0
votes
2answers
175 views

What was the first piece of hardware to utilise quantum effects? [closed]

Processors used to be mechanical, using macroscopic switches and gears. Then they began to use valve switches. Then they used microscopic circuitry that you could only see with a powerful magnifying ...
7
votes
3answers
4k views

Why plastic cases?

Early computers of the 'all in one' form factors, such as the Commodore PET, the early IBM microcomputers and later models of the TRS-80, as well as the 'box' form factors such as the Altair, used a ...
10
votes
4answers
518 views

Can the wrong sync frequency really destroy a CRT monitor?

I've read in various places that an incorrect signal of the wrong refresh rate can cause physical damage to a CRT monitor, but I've never found an adequate explanation of why this is so. Is this true? ...
6
votes
1answer
208 views

Testing RAM on a 386

I've got an old 386 laptop - specifically an OmniBook 300 - and I'm a little suspicious of the RAM. It's exhibited some very odd symptoms, such as memory-related crashes and boot failures, so I'd like ...
11
votes
3answers
1k views

What specific technical advance(s) allowed PCs to play “Full-screen full-motion” video?

In the early 1990s, the new buzzword for PCs was "Multimedia", and the gold standard for multimedia performance usually talked about was "full-screen full-motion" video playback. Many will remember ...
6
votes
1answer
152 views

Origin of the NZVC condition codes scheme?

The NZVC condition codes scheme, and corresponding set of 14 conditions for branches, is the nearly only in current ISAs that utilizes condition codes at all. The first computer I know that used it is ...
3
votes
4answers
452 views

Why is the ColecoVision AC adapter so big?

Why is it ColecoVision AC adapter so big? I never had seen someting like this in any console of the era or even after it. What are the design choices made by the designers? Was it to turn the project ...
30
votes
4answers
6k 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,...
6
votes
2answers
194 views

Did any pre-microprocessor CPUs have a clock near the toggle speed of the logic ICs used?

This question is NOT about single chip CPUs, but such that were built from many SSI/MSI logic ICs or using a bitslice configuration. A 74F... or 74S... type TTL gate or flipflop, if you provide them ...
8
votes
1answer
192 views

Did Charles Babbage design three Difference Engines?

At the British Science Museum they have four different models of Charles Babbage’s difference engines (including his designs). The display implied that he had at least three different designs. This ...
6
votes
1answer
209 views

what is the model of the cash registers used in Walmart in the mid to late 90's and very early 2000's?

what is the type or model of cash registers used in Walmart in the mid to late 90's and early 2000's? One can be found here: https://www.youtube.com/watch?v=3uy-tsXdY9s Note the strange sounds that ...
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 ...
0
votes
3answers
266 views

Which home-retrocomputers had a 1 single-color( no shades ) monochrome mode, or were by default? [closed]

THE QUESTION Which home-retrocomputers had a 1 single-color( no shades ) monochrome mode, or were by default ? EXTRA DETAILS ( I'm referring to home-retrocomputers in a time range from say 1976 to ...
0
votes
2answers
246 views

Didn't people 'back in the day', ever try 'Object-Tracking'( combined with RC ), via their retrocomputers, as 'Home-Projects'

Didn't people 'back in the day', ever try 'Object-Tracking'( combined with RC ), via their retrocomputers, as 'Home-Projects' ( I'm referring to a time range from say 1975 to 1985 ) ( Also, if ...
4
votes
1answer
209 views

Can't get the AY-3-8913 sound chip to work with my z80 (added schematic)

I'm trying to get the ay-3-8913 sound chip to work with my z80 but so far I haven't gotten any sound output yet. I know the chip, my amp circuit and the clock circuit work because it works when I ...
6
votes
1answer
477 views

Z80 ctc gold ICs speed

Does anyone have any information on what is the maximum speed for the gold ceramic z80 CTC?
11
votes
1answer
447 views

Why does the C64 have the following palette?

The Commodore 64 has the following fixed palette of 16 colours: (Your palette may vary due to tuning of screen, etc.) What was the reason for this selection of colours? Are these colours ...
25
votes
4answers
2k 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 ...
10
votes
6answers
980 views

Why did tactile-feedback keyboards lose popularity?

IBM spoiled me for hardware quality. I've gone through many computers, including a TRS-80, Heathkit H-89, Commodore Vic-20 and C-64, and countless PC's but my first original IBM PC will always be my ...
4
votes
1answer
171 views

Is there a way to get code off an old Sharp Wizard?

I have one of these lying around somewhere... There was a really cool game on it called Dungeon which I'd love to get the code for. Is that possible? What would be the steps to try? I do have the ...
6
votes
3answers
419 views

How do you find information about your hard drive in MS-DOS?

Context: I'm running an original MS-DOS. I suspect the hard disk is failing, but don't want to shut it off for fear of not being able to get it started again if I can't swap the hard drive into ...
54
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 ...
7
votes
1answer
160 views

In what ways is DRAM likely to fail?

A ZX Spectrum is likely to lose the same bit of every memory address if a single DRAM chip fails completely. However, if a DRAM chip partially fails, this could cause... interesting issues, ...
9
votes
1answer
189 views

When did Great Valley Products, stop producing hardware?

I had a GVP 68040 card in my old Amiga 2000 (ah those were the days). 25Mhz 68040, 16MB of RAM, SCSI controller to my 750 MB SCSI drive (if that was even 3200rpm I was probably lucky) and it was SO ...
4
votes
2answers
156 views

With better character handling capability, why didn't PC-98 system succeed in rest of East Asia?

From my understanding, an important advantage PC-98 have over IBM compatible PC was that it is better at handling ideograph based characters which are common in East Asian countries. Why didn't other ...
4
votes
1answer
335 views

How does the SAM Coupé refresh its RAM?

The SAM Coupé was a ZX Spectrum compatible computer with a 6MHz Z80, 256K RAM minimum, enhanced graphics and sound and an improved BASIC amongst other features. My question is about its memory. The ...
13
votes
3answers
2k views

Replacing 80286 with 68000

Suppose you wanted to take a 286 PC and replace the CPU with a 68000, not at the initial design stage, but actually modifying the finished machine, on the theory that they both have 24 bits of address ...
4
votes
2answers
332 views

Manufacturing cost breakdown for a 16-bit computer

The dynamics of the market, of what platforms end up being used at what times in what contexts, depend not only on what is technically possible, but even more on what can be done for what price, so ...
19
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 ...
11
votes
3answers
525 views

z80 crashes after executing some instructions

I'm building my own Z80 computer but I'm having a very strange problem. Consider this code: ld a,0xaa out (00),a jp a That works as expected, outputting 0xaa on port 0x00. Now consider this code: ...
4
votes
3answers
287 views

Retrieving text documents from a 2.0Mb/2.0 HD floppy disk?

I'm attempting to retrieve text documents from a floppy disk that is a 2.0Mb/2.0 Mo DS HD floppy similar to: The only thing he knows is that the documents were created on a mc around 1996. What are ...