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Questions tagged [hardware]

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

11
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2answers
1k views

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 ...
0
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0answers
80 views

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 ...
13
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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 -...
15
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1answer
316 views

Does anyone know the specific differences between the NES-001 (NTSC) motherboard revisions?

On each Motherboard of an NES-001 (NTSC) there is a code: NES-CPU-xx These range from 04 to 11 (I think) I would like to know if these are all of the revisions of the NES and what major differences ...
3
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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 ...
3
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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 ...
1
vote
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 ...
11
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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 ...
77
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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 ...
2
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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 ...
26
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9answers
8k 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 ...
4
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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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3answers
573 views

Can the CSG 65CE02 CPU be used to accelerate an Apple //e or //c?

The CSG 65CE02 is an improved 6502 microprocessor that was shipped in small quantities by Commodore around 1988. It is used in the Amiga A2232 multi-port serial controller card, and that would be the ...
4
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3answers
465 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 ...
-3
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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 ...
23
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9answers
5k 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 ...
2
votes
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 ...
12
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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 ...
11
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2answers
624 views

What was the A1200 Flash ROM support meant for?

Question inspired by this answer's last paragraph: https://retrocomputing.stackexchange.com/a/1307/2155 The Revision 1 A1200 schematics show that the system originally had support for a two internal ...
4
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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 ...
50
votes
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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0answers
124 views

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 ...
11
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8answers
2k 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, ...
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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 ...
6
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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 ...
4
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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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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 ...
48
votes
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, ...
6
votes
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, ...
23
votes
5answers
4k views

Why did Commodore sell CPUs to its competitors?

Many of the most popular personal computers and video game consoles of the 1970s and 1980s, including those made by Commodore, Apple, and Atari, used the 6502 CPU (or some close relative, such as the ...
24
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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, ...
1
vote
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 ...
9
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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 ...
4
votes
4answers
785 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 ...
2
votes
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 ...
2
votes
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 ...
9
votes
1answer
250 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 ...
3
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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 ...
2
votes
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 ...
12
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3answers
1k views

Is it possible to expand Amiga 500 rev 8 to 1.5 MB with a 1MB trapdoor expansion?

Is it possible to expand an Amiga 500 rev 8 (not an Amiga 500 plus) to 1.5 MB of Chip RAM using an A501+ expansion? It is plug and play or are modifications required? This is the board: Source: ...
8
votes
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
votes
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 ...
3
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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 ...
4
votes
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 ...
12
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4answers
591 views

Mind-Controller User Input from the late 90s

In the late 1990's, I recall that there was a piece of hardware being demonstrated in Best Buy that supposedly allowed you to control your computer via signals sent from your brain. How it worked is ...
4
votes
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 ...
3
votes
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 ...
41
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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 ...
87
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16answers
21k 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, ...