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Questions tagged [hardware]

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

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Method for adding firmware to a Commodore 64 expansion card?

The C64 expansion port can and does support multiple IO devices without conflicts. There is 0.5 KiB that is decoded for $DE00-$DFFF, using /IO1 and /IO2 on the expansion port. As long as the devices ...
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1answer
2k views

Why do old computers perform a long memory test on every boot?

Basically any computers from the mid 90s and earlier perform a slow memory check on every single boot. The more memory there is present, the slower that process becomes, for example: https://www....
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3answers
2k views

What happened to ZIP RAM?

I have several retro machines and add-on cards for the Amiga that use ZIP RAM. This vertically mounted chip design enjoyed a brief popularity in the early 1990s, in between the original DIP DRAM and ...
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1answer
152 views

Connecting Panasonic “Penwriter” RK-P400C to modern PC using USB to serial cable

I have a Panasonic "Penwriter" model RK-P400C electronic typewriter/plotter from circa 1985 I'd like to be able to connect to a modern PC. And hopefully even use to draw graphics! Bought in almost new ...
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2answers
310 views

Did DEC build their early computers out of the same parts?

Considering the PDP-8, PDP-7, PDP-9, PDP-1, even though they are completely different architectures (from a programmer's or compiler's point of view at least), they have some remarkable similarities ...
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1answer
314 views

On the bbc-micro, a half-size mode 1 screen mode with 16 colours instead of 4 can fit in memory but can the video chip be programmed for it?

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 ...
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3answers
178 views

TMS9918 with shared memory

The TMS9918 video display processor was designed in the 70s to have its own memory connected directly to it, and provides an interface that allows the CPU to read or write the memory during cycles in ...
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5answers
605 views

A different way to share the memory bus between the CPU and the Video

Considering the ZX Spectrum, part of the memory is accessible to both the ULA and the CPU, and the CPU is slowed down when it is using that area, so that the framebuffer can be read out. As I ...
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5answers
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Is my understanding right about the actual differences between 240p and 480i?

After reading around on the web, including the authoritative site Scanlines Demystified I still am having trouble understanding the difference in signal between 240p and 480i. After reading the wiki ...
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2answers
317 views

Strange “snow” artifacts when dragging a window in 256-color mode

I picked up a nice Packard Bell Legend 245 over the weekend, and it works great apart from one issue so far: when dragging windows around the screen (Win 3.1), the screen gets corrupted with weird ...
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0answers
157 views

When did green LEDs become as cheap as red LEDs? [closed]

Blue LEDs in the cheap, practical form we know them today, arrived in the 90s; before that, the choices were red and green. I want to say there was a time some years before that when green LEDs ...
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1answer
212 views

Recent article about using Apple II for security purposes

I'm looking for the article for a project. It is fairly recent, may have been a news article, or a blog. It in turn might have referenced a scholarly paper. Anyway, the gist of the article was that ...
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3answers
308 views

What is the optimal way to store retro computing paraphernalia (games, consoles, accessories, books) on display at home?

When collecting retro computing related items you'll undoubtedly end up with a variety of different items, made from different materials and in a range of conditions. Here is a recent snap of my ...
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8answers
11k views

Why were chips socketed in early computers?

In many early computers, many of the chips were in sockets rather than soldered directly to boards, e.g. this series of pictures of the Tandy CoCo 1 has a note to the effect that all the chips are ...
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2answers
139 views

Do all Econet devices need the same clock speed?

Econet was a network used by the BBC Micro, conceptually similar to Ethernet, two orders of magnitude slower and correspondingly cheaper. According to https://en.wikipedia.org/wiki/Econet it ...
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4answers
999 views

Largest practical motherboard for early computers

The power of a computer is often effectively determined by the size the RAM can be expanded to. In many cases, this was even more important than CPU speed: Memory-limited workloads In the early days, ...
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2answers
817 views

Smallest/Simplest, modern pure relay computer with at least 4-bits data words

There are a lot of designs out there of modern home made relay computers (not just ALUs but real computers -let's call them Turing complete, although Turing complete is not enough for having an ...
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4answers
5k views

What was computer “Fuzzy” logic?

In the mid 1980's computers began to be advertised as having or being capable of "Fuzzy" logic. How was "Fuzzy" logic added to a computer and what was it suppose to do better than a computer without ...
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5answers
325 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 ...
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0answers
203 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 ...
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1answer
339 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 ...
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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 ...
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2answers
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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 ...
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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?
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3answers
342 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 ...
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4answers
776 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 ...
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1answer
275 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)....
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7answers
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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. ...
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0answers
172 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 ...
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2answers
225 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 ...
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2answers
182 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 ...
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2answers
345 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 ...
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1answer
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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 ...
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4answers
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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 ...
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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 ...
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6answers
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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 were less common sizes such as 250 kB, 800 kB, ...
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1answer
222 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 ...
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2answers
187 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 ...
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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 ...
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5answers
667 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
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1answer
226 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 ...
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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 ...
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1answer
170 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 ...
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4answers
501 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 ...
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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,...
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2answers
203 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 ...
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1answer
200 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 ...
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1answer
215 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 ...
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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 ...
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3answers
275 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 ...