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Questions tagged [hardware]

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

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Material Specifications for custom CNC faceplate, style of Altair 8800

I'm working on a custom project, a computer/clock with LEDs and switches with the style of the original Altair 8800. I believe the original was aluminum, with silk screening, and with switches mounted ...
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1answer
2k views

What are Holorydmachines?

While going through the memoirs of a witness of the Holocaust in Germany, I stumbled upon the passage: there in Rudolfstadt we had a new holorydmachine from the Americans - in the barn of a farmer -...
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2answers
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Why did some CPUs use two Read/Write lines, and others just one?

Many 8-bit processors, such as Motorola's 6800 and MOS Technology's 6502 make use of a single pin to indicate to the rest of the system whether the CPU wishes to read from or write to a memory ...
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3answers
219 views

3 decimal digits per 10 bits

Early computers often had hardware support for decimal arithmetic. This was usually in the form of BCD, 1 decimal digit per 4 bits, e.g. the 6502 and Z80, tightly constrained by transistor count as ...
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1answer
89 views

Sam Coupé power supply heat

I have a Sam Coupé and the last time I turn it on, i noticed a smell of components overheating. After opening the power supply I came to the conclusion that is the resistance R1 (50ºc with IR ...
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5answers
442 views

Was it possible to send data over the phone-line without a modem?

Was it possible to send data over the phone-line without a modem? Clarification Was it possible to send data over the phone-line without a modem, either by connecting computers directly to the ...
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1answer
199 views

How to repair an old motherboard

I recently got some old motherboards. I was able to fix a damage caused by a leaked battery on a 486 board by soldering a bypass (to fix not working keyboard plug). Another board is in a good shape ...
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3answers
1k views

What was the first microprocessor to support full virtualization?

Virtual memory, which allows an operating system to run several machine code programs isolated from each other, came to the desktop during the eighties. But full virtualization, which lets the ...
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2answers
141 views

Single-stepping the Altair 8800

I've just been watching a rather interesting series of videos about the MITS Altair 8800. It has a button on the front panel to single-step the CPU one instruction at a time... Except that, on closer ...
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3answers
268 views

History of advanced hardware [closed]

Like most people, I grew up in the 1980s, and bore whitness to the great 8-bit home computer revolution. From where I'm sitting, "computers" started with slow 8-bit machines just powerful enough to ...
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0answers
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How To Save Magnavox Odyssey II Programs To Cassette?

Question - How could you have saved Magnavox Odyssey II ( more commonly written as "Magnavox Odyssey²" ) programs to cassette ? I am basing my question on saving programs written using using the ...
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12answers
10k views

How big is a mainframe?

If you read about the history of computing, you'll hear how the first computers were "huge". You will often come across assertions that in the early days of commercial computing, a single computer ...
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4answers
534 views

Amiga floppy disks and GCR vs MFM

According to https://en.wikipedia.org/wiki/Group_coded_recording the Commodore 1541 disk drive used a particularly efficient GCR encoding scheme to cram 170K onto the same 5.25" disks that in an Apple ...
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4answers
233 views

Operating systems which have non-x86 instruction set architecture [closed]

What are the most famous operating systems for non-x86 computers? I mean, most famous OS which have different instruction set architecture. Background (to better understand my task): I ask this ...
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7answers
3k 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 ...
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3answers
809 views

Parallel to serial conversion

Two very common connectors used in the eighties were the Centronics parallel port (particularly used for printers) and the RS-232 serial port (particularly used for mice and modems). Suppose you have ...
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18answers
17k views

Have programming languages driven hardware development?

Programming language development has been influenced by hardware design. One example from this answer mentions how C pointers were, at least in part, influenced by the design of the PDP-11. Has the ...
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2answers
217 views

When did game consoles acquire battery-backed clocks?

The importance of a desktop PC knowing the current time could be debated, but it is clear IBM felt it to be important, for the IBM PC typically prompts the user to supply it on boot. Given that, the ...
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11answers
13k views

Why did trackballs disappear?

For a desktop computer, a mouse is a great pointing device. For a laptop if you don't want an extra device to keep track of, you need an alternative. The options I'm aware of: NubLow-tech, cheap, ...
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3answers
4k views

386SX, NES and how much did data lines really cost anyway?

In 1988, Intel introduced the 80386SX, most often referred to as the 386SX, a cut-down version of the 80386 with a 16-bit data bus mainly intended for lower-cost PCs aimed at the home, educational, ...
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1answer
431 views

Wider tower cases

Desktop computers have been in tower cases for a long time; in some cases since the eighties, per When did the tower form factor appear and when did it become popular? The form of tower cases has ...
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3answers
729 views

IBM PC expansion card latency

In the IBM PC and early successors and compatibles, it was commonplace for most of the computer's memory to be on cards in general expansion slots. (e.g. the original IBM PC could take 64K on the ...
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1answer
226 views

What was the purpose of GROM (vs ROM) in the TI-99/4a?

The TI-99/4a had a cartridge slot on the front of the computer which accepted "solid state cartridges" (as TI called them). These cartridges would typically contain ROM (Read Only Memory) like many ...
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1answer
274 views

Did any Apple II games use a “timing resistor”?

A science-lab program for the Apple II (I forget the name) had a board that plugged into the joystick port and included a "timing resistor". While I don't know what the program actually did with the ...
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4answers
1k views

Did any machines alternate between two video memory banks?

If a home computer or console has two banks of memory, A and B, then the following design is possible: The video chip only connects to bank A. The CPU connects to both. During active scan line, CPU ...
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1answer
261 views

Why does the SNES have a separate memory bank for sound?

According to https://snescentral.com/article.php?id=0088 the SNES has the following memory banks: Work RAM for CPU - 128 Kilobytes (CPU temp. storage) Video RAM for PPU - 64 Kilobytes (temp. storage ...
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1answer
290 views

When were other inexpensive computers able to recreate “The Amiga Juggler”? [closed]

The Amiga Juggler was the 2nd very popular demo to appear for the Amiga Computer early in its lifespan. The demo was created by Eric Graham (who went on to develop Sculpt3D) using raytracing to both ...
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1answer
322 views

How did Parallel ATA/IDE Independent Device Timing work electrically?

Back in the days of Parallel ATA (a.k.a. IDE) it was possible to connect two drives with a single cable. The ATA standard defines a number of modes with different speeds which the drives and the ...
8
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1answer
237 views

What's the purpose of HOLD command in 6502 stack pointer

In the Block Diagram the Stack Pointer Register (S) has a HOLD command in addition to the LOAD and BUS ENABLE commands. The HOLD command is linked to the S/S output of the Random Control Logic. What ...
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2answers
284 views

How significant/pioneering was the TV Typewriter?

How significant and pioneering was the TV Typewriter, in light of things like calculators with CRT's from 1964 and various other things? I recently read that the TV Typewriter established the standard ...
3
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1answer
144 views

Ways To Test iMac G3 Before Buying

I am going to buy an old iMac G3 Over the next couple of days/weeks, and I want to make sure that I am buying a system with no problems. I usually ask for the serial number and good pictures before ...
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3answers
782 views

what OS runs Zip drives? [duplicate]

I came across my old Zip drive and some Zip disks. I am curious what is on the disks, but my Windows system won't run them. Back in the day I thought that these would be the ultimate in archive ...
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4answers
2k views

Purpose of two disk drives on the Osborne 1

I recently discovered the Osborne 1 computer, and I noticed it had two floppy disc drives. What was the purpose of including two drives?
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4answers
499 views

What is the basic logic behind the setting or ordering of keys in a keyboard?

I am a computer science student. I mostly work with computers and I am really wondering about the layout of keys in a keyboard. It is comfortable and easy. My question is this: what is the basic ...
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2answers
437 views

What's with the empty space on this die?

Here is the Valvo 2650. (Also known by other names, in the UK as Signetics 2650). What struck me about this image is the amount of empty space! If you look at a modern-day chip, say a Skylake or ...
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1answer
187 views

Is there a comparative analysis of the evolution paths of chips inheriting from TMS9918?

This is primarily about VDP from the Sega Master System game console and video chip from the MSX 2 series computers. Specifically about Yamaha YM2602 (aka Sega 315‑5124) and Yamaha V9938 respectively. ...
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2answers
3k views

Reason for gold lines on old ICs?

A lot of older (ceramic) ICs have a gold-plated line extending from the die cover to the edge of the package. Did this serve a practical purpose or was it just bling? I suspect that it might be what'...
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5answers
6k views

Using DRAM as a camera sensor?

Back in the days when COMECON (RVHP) was cloning digital ICs usually the first wave of such ICs were in a ceramic package with a glass window (similar to EPROM) to check for bugs and stuff while used. ...
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3answers
165 views

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

What was the earliest date a home-computer or home-robot could be interfaced with a tv-camera or digital-camera . Robots were often based on home-computers . Although I'm asking this question for ...
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17answers
6k views

Simplest system to create an emulator for

Next year I'm going to teach a 2-semester microprocessors class to third-year undergraduate EE students. In order to sign up for the class, students need to have completed programming and digital ...
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2answers
244 views

Is it possible to upgrade original iMac (1998) memory (RAM) to above 256 MB?

I am looking into buying myself an original iMac, as I want to mess with the older system a little bit. Is it even remotely possible to change the RAM in the system to being over 256 MB? I am willing ...
6
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1answer
286 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, ...
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4answers
604 views

Is the N64 incapable of 2D graphics?

So as many fans are aware, the N64 era was a jump for many games into the third dimension. Games like Mario and Zelda were impacted in a positive way. Others... not so much. While it may seem odd that ...
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1answer
211 views

“Unexpected interrupt in protected mode” after installing 486 DX2

I've got a Packard Bell Legend 245 that's been running a 486 DX at 33 MHz. The board is Socket 2, and says Intel Overdrive Ready. I bought a 66 MHz DX2 under the assumption that it's just a drop-in ...
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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 ...
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2answers
278 views

Do TG16 games and software suffer from lag frame similar to NES Super Mario Bros?

As a speedrunning fan, I've watched hours of Super Mario Bros speedruns, and have heard the term "lag frame". I don't think it's similar to typical computer lag, but instead an extremely technical ...
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1answer
495 views

RAM for Socket 7 Motherboard - 64MB sticks appearing as 16MB

I hope this is the right place to ask this and that it is "retro" enough. I have a Socket 7 machine that I am working on. It's my 1st PC from childhood that I restored, and now I would like to ...
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2answers
193 views

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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2answers
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
3k 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 ...