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Questions tagged [hardware]

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

103
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4answers
23k 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 ond old computers: I don't know if this was a Windows 95/98/2000/ME only thing but I wonder why ...
87
votes
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, ...
80
votes
20answers
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 ...
58
votes
5answers
13k 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 ...
54
votes
6answers
7k views

Reason for the Amiga clock speed

The Amiga used a CPU rated for 8 megahertz, but clocked at 7.14 megahertz. What was the reason for this number? I remember it was something to do with a multiple of the frequency of the video ...
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 ...
48
votes
11answers
14k 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, ...
43
votes
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 ...
42
votes
2answers
4k 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 ...
41
votes
17answers
7k 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 ...
39
votes
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 ...
37
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5answers
5k views

Why do programmable sound generators like SID include a noise generator?

In layman's terms, please explain the reason that all the popular PSG's used in 1980s computers and game consoles provided an additional channel to generate programmable "noise". How was this "noise" ...
33
votes
4answers
7k 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,...
31
votes
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. ...
30
votes
8answers
8k views

Why do articles use the term “UART” instead of “serial port”?

I am learning about old computers, and I have found the following image from this article: They use the terms "UART" instead of "serial port" and "UART driver" instead of "serial port driver", I have ...
29
votes
5answers
6k 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 ...
26
votes
7answers
11k 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. ...
26
votes
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 ...
26
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3answers
1k 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 ...
26
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 ...
26
votes
1answer
2k views

What are the Amiga 1200 timing fixes?

I have read that the Amiga 1200 may need certain "timing fixes" to be applied to the motherboard in order to use CPU accelerators. What are these timing fixes and why are they needed? Is there one ...
25
votes
3answers
5k 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, ...
25
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1answer
2k views

How can I take an image of a 50-pin SCSI hard-drive

I have two 50-pin SCSI hard-drives that I need to image. However, after spending quite a while searching across the Internet, I cannot find any adapters to convert the 50-pin connector to something ...
24
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16answers
2k views

What 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 ...
24
votes
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 ...
24
votes
2answers
3k views

How does the NES Light Gun work?

Modern motion detection video game systems (Wii/Wii U, Xbox Kinect, PS Move, etc.) need sensors to read for motion and user input. However, when you play Duck Hunt (and some other games) on the NES, ...
24
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4answers
2k views

Which ports are which on this Soviet ZX Spectrum clone?

Today I got my (first) Soviet ZX Spectrum clone. The person who sold it to me had inherited it and had no idea how it worked. It seems to be a home-made clone, rather than a factory-built one. See ...
24
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3answers
3k views

Adapting a “modern” keyboard to a ZX Spectrum

Is there a way, such a specific interface adapter, which would allow me to connect a PS/2 keyboard to an original ZX Spectrum? I expect the keyboard to work similarly to the ZX Spectrum itself -- in ...
23
votes
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 ...
23
votes
4answers
3k 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
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 ...
23
votes
2answers
2k views

Why did connecting the IBM PC 3.5" FDD backwards cause the problems it did?

When the 3.5" FDD was introduced for the IBM PC and compatibles (or possibly earlier), someone made a decision to make the data cable between the controller and drive unkeyed. This, of course, meant ...
23
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3answers
2k views

Main board of the original Game & Watch (Ball)

The Game and Watch was a series of single-title games consoles created by Nintendo from 1980 until 1991. Each machine contained a custom LCD screen (containing images related to the software), some ...
23
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3answers
2k views

Why did so many early microcomputers use the MOS 6502 and variants?

Quite a few successful early microcomputers used the MOS 6502 CPU. This included, but was not limited to, systems like the Apple I, Apple II, Commodore PET, and Ataris. A followup known as the MOS ...
22
votes
5answers
2k 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
3answers
2k 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 ...
22
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2answers
1k views

Why does waggling the joystick of a C64 cause errors loading from tape?

When loading a game from the tape drive on a C64, if you wiggle the joystick around too much the program will not load correctly. Is there an explanation for this? EDIT: Perhaps someone can try to ...
21
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3answers
3k views

Does an ISA card have a fixed memory address?

A PCI card does not have a fixed memory address, the PCI card specifies how much memory it wants, and the OS will assign whatever address it wants for this memory, and will set this address in the PCI ...
21
votes
3answers
3k views

When you type on a computer terminal, how are the characters displayed on the screen?

Assume that the following computer terminal is connected to a large computer: When I type something on the keyboard (for example: pwd), is it the computer terminal the one that receives the ...
20
votes
3answers
3k views

Did arcade monitors have same pixel aspect ratio as TV sets?

It is well known that when emulating classic games on modern displays, you need to be careful not to distort the aspect ratio. Generally speaking, CRT screens were 4:3, and specific pixel aspect ...
20
votes
4answers
2k views

Why does MP3 audio decoding overwhelm retro CPU's?

Many retrocomputers from the late 80s and early 90s had audio DAC hardware support. This includes the Amiga, Classic Macintosh, and PC's with SoundBlaster add-on cards. Despite the fact that the MP3 ...
20
votes
1answer
681 views

What is the difference between the “Return” an “Enter” key in the VT100 terminal?

What is the difference between the "Return" an "Enter" keys in the VT100 terminal:
19
votes
3answers
1k views

Documentation for the ZX Spectrum ULA

I am writing a Spectrum emulator, however I am finding it difficult to find official or reliable information about the ULA, its functioning and its pins. Are there official sources documenting its ...
19
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3answers
2k views

Adjusting focus for old CRT monitors

I have an old Atari SC1224 CRT which has badly lost focus over the years. After taking the cover off, I can see various focus controls that can be adjusted by screwdriver. Question: is there a ...
19
votes
5answers
2k 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 ...
19
votes
2answers
3k 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 ...
19
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4answers
3k 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
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1answer
771 views

Are the effects of “Retro-Brighting” permanent or temporary?

As many of you know, plastics used in our beloved computers from the 70's, 80's and 90's contained a fire retardant called Bromine. This chemical (along with exposure to the Sun's ultraviolet rays) ...
18
votes
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 ...
18
votes
5answers
2k views

Cloning circuit boards for antique computers?

Would it be feasible to create direct clones of obsolete and increasingly hard-to-find motherboards and controller boards for vintage computers? Most of the early 1980s technology was either single ...