Questions tagged [hardware]

Retro hardware generally: boards, extension cards, power supplies, peripherals. Use more specific tags as appropriate; use [case] instead for enclosures.

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48
votes
6answers
17k 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 ...
131
votes
4answers
40k 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 on old computers: I don't know if this was a Windows 95/98/2000/ME only thing but I wonder why ...
62
votes
5answers
14k 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 ...
49
votes
4answers
6k views

Why did the IBM 650 use bi-quinary?

The IBM 650, announced in 1953, was the world's first mass-produced computer. It represented numbers in decimal, which is understandable, both because it needed to work with exact money amounts, and ...
21
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3answers
6k 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 ...
0
votes
3answers
353 views

The earliest a home-computer or home-robot could be interfaced with a commercially available camera?

What was the earliest date a home-computer or home-robot could be interfaced with a commercially available tv-camera or digital-camera . Although I'm asking this question for the purpose of computer-...
97
votes
17answers
24k views

How was early randomness generated?

Many programs make use of randomness, from BASIC guess-the-number games to encryption key generators. This randomness could have been generated in many, many different ways: hardware, software, ...
40
votes
4answers
8k 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,...
56
votes
6answers
17k views

What did the 'turbo' button actually do?

I remember the computer I played Commander Keen on as a child had a turbo button that I was forbidden to touch, what did this button actually do?
26
votes
10answers
7k 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 ...
24
votes
2answers
3k 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....
13
votes
1answer
641 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, ...
4
votes
7answers
1k 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 ...
23
votes
4answers
4k views

What accounted for the cost of ENIAC?

I'm used to the fact that first-generation computers were very expensive, which I had always assumed was because they contained large numbers of vacuum tubes, each of which is a rather complex, high ...
18
votes
5answers
3k views

Can a retro-computer be a useful way to learn computer-architecture fundamentals?

I've been reading about the fundamentals of computer architecture, but I think I could get a better grasp of the basics if I could could have an actual device to play with. I had considered building ...
13
votes
7answers
4k views

Were there any "off the shelf" graphics chips that supported 2D sprites in the 70's and 80's?

I'm looking for "off the shelf" graphic IC's that supported hardware sprites. By "off the shelf" I mean chips that were designed to be used in various machines and not designed specifically for one ...
29
votes
9answers
11k views

Should 486s have a heatsink?

I'm building a 486 computer. I plan on using a 100 MHz 486-DX4 that I have which I believe is about as fast as 486's went. The motherboard I will use (Socket 3) appears to support putting a heatsink ...
28
votes
7answers
12k 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. ...
6
votes
5answers
5k views

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 ...
23
votes
8answers
5k views

Why not constant linear velocity floppies?

The outer tracks of a disk are longer than the inner tracks, and could therefore potentially hold more data. Constant angular velocity puts the same number of bits on every track, which wastes much of ...
16
votes
5answers
2k 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 ...
26
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4answers
4k views

What register size did early computers use?

Prompted by this question querying the prevalence of byte-addressable memory on machines with 32 bit registers: Why is every address in a micro-controller only 8 bits in size? I'm familiar with the ...
23
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7answers
4k views

Was it possible programmatically to manipulate the volume as well as the pitch on computers with no sound chip?

On early versions of many 8-bit computers like the Apple II, Spectrum, and even the IBM PC, there was no sound hardware other than the simple "beeper". Programmers made sound by hitting a hardware ...
17
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6answers
5k views

Can removing a cartridge from an NES (or any other cartridge-based game system) damage the hardware or software?

On some cartridge-based video game systems (NES, Game Boy Color, etc.) it is possible to remove the cartridge while the game system is still powered on. What kind of damage can this behavior do to ...
17
votes
2answers
1k views

Power cycling old hardware

For those of us that use an old computer daily, is it safer for the hardware if the machines are turned off every night, or should they be left on? I assume that powering up is more stressful for the ...
14
votes
3answers
3k 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 ...
13
votes
5answers
3k views

Mapping more than 64kb of address space

I'm planning out a 6502 homebrew build but seem to be stuck in the issue of buying parts. My plan is to extend the addressing capabilities of the 6502 by giving myself 64kb of RAM, and another 64kb of ...
13
votes
1answer
2k 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 ...
29
votes
1answer
2k views

How do Amiga 600 CPU accelerators work?

The Amiga 1200 has a trapdoor expansion for CPU accelerators. The Amiga 500 has a side expansion port and its CPU is socketed. But Amiga 600's expansion port is only useful for memory expansion ...
28
votes
3answers
3k views

What are the differences between a PAL and NTSC C64?

A lot of programs released for the Commodore 64 contained different software for the PAL or NTSC computer. Why did they have different versions of the hardware? Did the software have to be different ...
24
votes
5answers
3k 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 ...
20
votes
5answers
6k views

Was 10BASE5 a mistake?

https://en.wikipedia.org/wiki/10BASE5 gives a succint but vivid description of the physical layer of the first version of Ethernet and its subsequent replacement: 10BASE5 (also known as thick ...
20
votes
7answers
9k views

Did any computer use a 7-bit byte?

In an answer to Why did IBM System 360 have byte addressable RAM I wrote regarding the choice of byte size: 7 bits would be a perfect match for ASCII, but engineers would instinctively recoil from ...
13
votes
5answers
397 views

Preventing socketed chip corrosion?

I spent a couple hours repairing an Amiga A3000 that wouldn't boot yesterday. The fix was to remove Kickstart ROMs, clean the DIP leads and sockets with contact cleaner, and re-insert. Apparently a ...
12
votes
4answers
5k views

How can a ST-412 MFM hard drive be integrated with a modern PC?

I have a Seagate ST-225 20MB hard drive. It used a ST-412 MFM (Modified Frequency Modulation) controller which unfortunately went to the great bit bucket some time ago. Is it possible to get this ...
11
votes
1answer
1k views

How can I edit CMOS hard drive geometry settings on a 1991 PC?

First, I am NOT asking how to use the BIOS Setup utility. I'm asking how to OVERRIDE the built-in settings my BIOS Setup supports for the HD geometry. I have a 1991 NCR PC with a 386SX, on-board IDE, ...
4
votes
0answers
170 views

Why did Gran Trak 10 cost so much?

In 1974, Atari released a driving game called Gran Trak 10. The development prototypes had used real car steering wheels and pedals, but it was realized these were too expensive, so they were changed ...
24
votes
3answers
3k views

Why did the Atari 800 designers choose such a radical system design?

The physical system design of the Atari 800 was pretty radical, when compared to the 3 other canonical home computer designs of the late-1970s: TRS-80 Model 1, PET, and Apple ][. As the photo of the ...
24
votes
5answers
5k views

How do you open an SE/30? (a.k.a. what is a "pull-apart tool"?)

I have been trying to work out how to open a Mac SE/30, in order to have a better look at its internal condition. I have the repair manual, and in the "Take Apart" section it references a "pull-apart ...
22
votes
4answers
4k views

How did the Amiga 500 left-side expansion port work?

On the Amiga 500 there is an expansion port How did the expansion port work?
19
votes
1answer
3k views

Did 5.25" floppies undergo a change in magnetic coating?

3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant ...
18
votes
6answers
7k views

How much data could a home computer store on an audio cassette?

The use of audio cassettes for storing data for home computers was a great example of repurposing an existing invention. Cassettes were sold in a variety of capacities, and labelled with their audio ...
16
votes
1answer
622 views

Why was the audio output of the SID6581 so variable between chips?

Each of the SID6581s I have tested sound different, particularly when it comes to filter cutoffs and distortion. What are the causes of these variances?
16
votes
1answer
2k views

How do accelerators and CPU cards work on the Apple II?

An Amiga 1200 exposes the entire CPU bus on the expansion port, so that an accelerator only needs to assert BR which causes the onboard CPU to stop all computation and electrically disconnect from the ...
16
votes
5answers
4k 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? ...
15
votes
1answer
857 views

What is the Kelly chip?

The Amiga 3000+ DevCon 1991 notes says: On the A3000+, these resources include the Amiga "Pandora" chip set (Alice, Lisa, Kelly, and Paula), However, a Kelly chip is not part of the official ...
15
votes
3answers
2k views

Who decides what is the memory address that the CGA video buffer will be mapped to?

In DOS, the memory mapped IO base address for the CGA video buffer is 0xB8000. So when you write to 0xB8000, you are actually writing to a buffer in the CGA card itself and not to RAM. What I want to ...
14
votes
5answers
3k views

Can I run Windows 98 and games from the same era on an AMD Duron CPU?

I have acquired an old motherboard with a socket 462 and a AMD Duron (I think its a "Spitfire" model 3). The copyright on the CPU is from 1999 and it apparently doesn't require a dedicated CPU fan as ...
13
votes
8answers
4k 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 were less common sizes such as 250 kB, 800 kB, ...
13
votes
1answer
853 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 ...