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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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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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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 ...
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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-...
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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?
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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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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,...
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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 ...
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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 ...
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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 ...
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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 ...
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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, ...
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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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Can the Gotek floppy emulator be made to work with classic Macs?
The Gotek floppy emulators are really popular in the retro scene. I have one modified (firmware update) to work with my Amiga 500.
Can one be made to work with any of the classic line of Macintosh ...
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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 ...
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Did the IBM Game Control Adapter have I/O port aliases?
I was taking a look at the logic diagram in the manual for the original IBM game port adapter card:
In the upper-left corner of the schematic, there is the circuitry responsible for decoding the I/O ...
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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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Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?
In short, 3 µm looks like it was the "standard" process size at the time, and it was available to Commodore before the chips were designed. Therefore it looks like using the larger 5 to 7 µm process ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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DIY Project using 1970s 8-bit CPU, is it possible?
I've recently really wanted to try and design a computer system around a retro 8-bit CPU such as the Zilog Z80 or the Intel 8080, and I would appreciate some sanity checks! I was inspired by Ben Eater'...
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When did 5.25″ floppies exceed the capacity of 8″?
When 5.25″ floppies were introduced, in the mid-to-late seventies, they would have had less capacity than the older 8″ because, well, less area on which to store data.
On the other hand, being cheaper ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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? ...
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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 ...
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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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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?
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