Questions tagged [hardware]

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

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4
votes
3answers
604 views

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

I'm attempting to retrieve text documents from a floppy disk that is a 2.0 MB DS HD floppy similar to: The only thing he knows is that the documents were created on a Mac around 1996. What are some ...
12
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4answers
1k views

Did Apple bundle a specific monitor with the Apple II+ for schools?

Sometime in 1980 (or maybe 1981) my school district purchased its first batch of Apple II+ computers. I remember vividly they had absolutely no idea what to do with them, and so the machines were ...
2
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2answers
257 views

What was the DRAM refresh interval on early microcomputers?

Dynamic RAM is denser than static RAM, but needs to be refreshed every few milliseconds to avoid losing data. How many milliseconds, exactly? If the answer has changed over time, then I'm interested ...
8
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2answers
703 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 ...
26
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3answers
5k views

Why does DOS ask for the current date and time upon booting?

In most versions of DOS, when they are started from a medium that lacks an AUTOEXEC.BAT file, the very first thing COMMAND.COM does is ask the user to confirm the current date and time: Starting PC ...
16
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5answers
799 views

What is known about the Wang VS series CPUs?

I'm trying to do research about the Wang VS series, and there's very little on these computers on the internet (as the company was effectively dead before the internet era, this is hardly shocking). ...
26
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23answers
3k views

Which computers had redefinable character sets?

My first computer was an Exidy Sorcerer, bought in the late '70s. It featured a full keyboard including lower case, on screen text of 64 B&W characters by 30 rows, 2 MHz z-80 processor, up to 48 ...
9
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9answers
3k views

Were any external disk drives stacked vertically?

There was a time when floppy disk drives were big, expensive devices that in many cases, instead of being components of a computer, would be separate machines connected by a cable, in some cases with ...
4
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3answers
686 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 ...
3
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1answer
250 views

Did the Nintendo S-SMP really contain 3 million transistors?

According to http://www.vgmpf.com/Wiki/index.php?title=S-SMP The S-SMP (perhaps: Sony - Sound & Music Processor?) is the audio CPU used by the Super Nintendo Entertainment System. It consists of ...
7
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1answer
218 views

Player 1 / Player 2 input for Space Invaders

According to the Computer Archeology page on Space Invaders, port 1 presents "player 1's shoot/left/right" input to the CPU, whereas port 2 presents player 2. Playing around the code in an ...
6
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3answers
372 views

What is the difference between the 6522 VIA and a UART?

The 6522 VIA is an I/O chip used in the Vic-20. I was under the impression that UART (Universal Asynchronous Receiver/Transmitter) is the general term for such chips, so was surprised to see this: ...
20
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11answers
5k views

Did any European computers use 10-line fonts?

Most 8-bit computers implemented hardware text mode, and most of those used 8x8 fonts. This was logical for American computers; the title safe area on NTSC is about 200 scan lines; font height 8 gets ...
3
votes
1answer
601 views

Why does the Vic-20 have two VIA chips?

The Vic-20 uses the 6522 VIA for peripheral I/O. However, it has two of them. I find this surprising, particularly considering minimizing cost was an important design goal. Is there a reason why it ...
11
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6answers
1k views

When did the tower form factor appear and when did it become popular?

Essentially, my question is there in the title. Tower cases are commonplace these days, and probably are the "default" form factor for personal computers (or at least were, before they were surpassed ...
2
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1answer
223 views

Why did the Vic-20 need special chips for I/O?

The Vic-20 used two 6522 VIA chips for I/O. I asked why it had two of them but thanks to a comment from Bruce Abbott, I now think that wasn't quite the question I needed to ask. What I really need to ...
6
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4answers
2k views

Could any computers use 16k or 64k RAM chips?

An interesting feature of the Apple II was that it had three rows of sockets for RAM chips, each of which could take either 4k or 16k chips. That meant the minimum configuration was 4K (cheap) but it ...
8
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1answer
437 views

Was sector size under software control on the original IBM PC floppy drive controller?

The original IBM PC used a 5.25" floppy disk format of two sides, 40 tracks, 9 sectors per track, 512 bytes per sector, for 360K per disk. As I understand it, a significant amount of disk space ...
48
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4answers
5k 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 ...
18
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2answers
4k views

Is it possible to adapt a standard PC floppy drive to work in an IBM PS/2?

I have three different IBM PS/2 machines and all of them are in perfect working order—except for the floppy drives. None of the floppy drives will read disks, which means all I can do is key in BASIC ...
6
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2answers
362 views

Why did the CDC 6600 expand the word size to 60 bits?

According to http://www.quadibloc.com/comp/cp0201.htm The CDC 1604 used 48-bit floating point with 11 bits exponent and 36 bits mantissa. There was also a double precision format (which I believe was ...
2
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1answer
96 views

Macintosh IIci not booting

I have an old Macintosh IIci that worked until a few weeks ago but now doesn't turn on anymore. When I press the power button on the keyboard all the lights on the keyboard and the one on the main ...
15
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2answers
2k views

Why did the 8087 need a special socket?

The IBM PC included a coprocessor socket for the 8087 floating-point unit. Logical enough; some customers wanted to use the 8087 to make numeric calculations run faster. But why was the 8087 designed ...
20
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5answers
5k views

Why did mainframes have big conspicuous power-off buttons?

Some fascinating stories in this discussion thread. It starts with discussion about computers overheating, but about halfway through the thread, it switches to discussion of mainframe installations in ...
3
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0answers
134 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 ...
18
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8answers
3k views

Why user-assembled kits?

Many early computers were sold as self-assembly kits (you get a box of parts and an instruction leaflet and have to solder them together yourself). For example, the Altair was priced at $439 kit, $621 ...
3
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2answers
379 views

How did wave soldering work? [closed]

While it is not used as much nowadays, wave soldering was a big advance in the productivity of manufacturing electronics, compared to soldering all the components by hand. It consists of placing all ...
9
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2answers
672 views

Did any 8-bit CPUs use dynamic memory for registers?

According to https://jamiestarling.com/project-8088-the-8088-cpu-pinout/ One thing to note – the 8088 registers are made from dynamic memory cells – they have to be refreshed. The minimum clock speed ...
12
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4answers
851 views

Did the Commodore datasette interface provide greater reliability?

Cassette, being cheaper than a floppy disk drive, was a popular storage medium in the 8-bit era. Some computers such as the Sinclair Spectrum, just provided a port to plug in an existing cassette deck....
13
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4answers
1k views

How did 2-chip CPUs work?

The 1970s saw a big transition from CPUs built from thousands of discrete components, to CPUs implemented on a single chip, with the occasional use of bit-slice components along the way. There were, ...
3
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2answers
225 views

Could the 6502 have worked with an Altair-style front panel?

I have fond memories of programming the 6502, though I never did any hardware hacking with it. I notice that the Altair, with its iconic front panel, was based on the Intel 8080, and from then on, ...
18
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1answer
3k views

What is the function of this strange IBM apparatus?

Does anyone know what kind of device this is? I found it in my late dad's stuff, probably from the 1970s. It has no number, type, model, serial number or anything else on it that could be used for ...
12
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4answers
4k 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 ...
10
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2answers
479 views

S-100 bus and device drivers

It is said that the S-100 bus provided a standard hardware format for expansion cards across many models of computers, including ones using different system software and even different CPUs. Having ...
2
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1answer
109 views

Intel vs Motorola device communication protocols

On this page about "An S-100 68000 CPU Board" it is said: From a hardware perspective there are some very significant differences how Intel and Motorola CPU's talk to the world. Somewhat ...
20
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7answers
4k 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 ...
36
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2answers
3k views

Was AGP only ever used for graphics cards?

Reading on the AGP spec, the little bits I've found on sites like https://old.pinouts.ru/Slots/agp_pinout.shtml, say: The Accelerated Graphics Port (also called Advanced Graphics Port) is a high-...
1
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1answer
112 views

Why was the SWTPC 6800 Computer System cheaper than the Altair?

In 1974, Intel released the 8080, which basically was the first microprocessor good enough to build a serious computer around. That led to the Altair 8800 the following year, which was the beginning ...
11
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2answers
1k views

Was natural convection ever a consideration in orienting expansion cards?

Many computers have followed the design pattern of a backplane with expansion cards, including arguably the three most influential microcomputers ever built: the Altair 8800, the Apple II and the IBM ...
10
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3answers
597 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? See this video. Note the strange sounds that Ann says is when the cash register is printing. Also ...
6
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2answers
338 views

VAX 11/780 16MB memory board - what was the physical size?

I'm trying to get a feel for what it looked like when you designed a computer to have a lot of memory chips stuffed into it. To that end, I found this: https://commons.wikimedia.org/wiki/File:...
5
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1answer
322 views

How much did the RM 380Z weigh?

The Research Machines 380Z was an early British microcomputer, released in 1977. Unlike many other early microcomputers, the design was industrial style, a hefty metal box, sometimes described as '...
13
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5answers
385 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 ...
18
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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 ...
2
votes
2answers
133 views

How to limit RAM available to Workbench

Is there a way to limit Fast RAM used by Amiga OS 3.1, i.e. if A500 with 030 MMU detects full 64MB in address ranges 0x40000000 to 0x44000000. Instead, can I choose to map only 8MB in lower ranges at ...
4
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2answers
764 views

Bakelite as data storage

Was bakelite used for computer data storage like it was used for grammophone records? My brother says he remembers this but I cannot find it on Google.
5
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2answers
342 views

Vintage computer composite graphics

I am working on designing a vintage computer and I have been using the TMS9918ANL. After working with it for a month or two and not making much progress, I really want to switch to another chip. I am ...
1
vote
2answers
297 views

Performing 16-bit port I/O on the RTC

Why can’t the RTC (0x70, 0x71) read and write 16 bits at a time? For example: mov ax, 0xa8f out 0x70, ax I have found in a 286 BIOS that did this (BIOS ID string: S286-6181-...
11
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1answer
798 views

How did the Zip Chip and RocketChip accelerators work for the Apple II?

Though there is already a similar question on the site, this one is more specific to these chips and their technical implementation. There were two accelerators for the Apple II series that were drop-...
6
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4answers
224 views

Does anyone remember analog computers in the early 70s? [closed]

In 1972, when I was 16, I was sent on a one-week computing course at the local technical college in Worcester (UK). I was one of a group of girls who were intending to take Maths A-level the following ...

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