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9
votes
1answer
565 views

What was the difference between “Video Low” and “Video High” on the VIC-20?

I was reading about the Audio/Video port pinouts of the VIC-20 and I noticed that pin 4 is VID L and pin 5 is VID H meaning Video Low and Video High, respectively. I'm familiar with luma, chroma, etc....
8
votes
1answer
295 views

How many bits are stored in a memory location in a PDP-11?

PDP-11 is said to be word addressable, which means every data access returns 16-bit data. Suppose I give a read request for address 100 in memory. Will it return 8 bits (LSB) from address 100 and ...
19
votes
2answers
2k views

Is there a better way to the 6 disks install of Windows 3.1

I want to install Windows 3.1 on my MS-DOS 6.22 Machine. I have the 6 disk images. But I only have 1 or 2 spare Floppy disk that I can write the disk images onto. One way I can think of is to write ...
10
votes
2answers
750 views

Did the VIC-20 support raster scanline tricks like the Commodore 64?

I've been programming the C64 on/off for over 30 years (wow). However, I have a few VIC-20's I want to program. I never had a VIC-20 as a kid so I haven't had much exposure to them. Am I correct in ...
6
votes
1answer
399 views

Can you get the file descriptors of a process in UNIX V7?

In Linux, if I want to get the file descriptors of a process, I would go to the following directory: /proc/<pid>/fd But in UNIX V7, the /proc directory does not exist.
10
votes
2answers
296 views

Where to find thermal paper for Aquarius or Commodore printer?

The thermal printer that was sold for use with the Mattel Aquarius or VIC-20 / Commodore 64 is an Alphacom VP42. This uses thermal paper, 4 3/8" wide. Original paper for these printers is very ...
13
votes
3answers
2k 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: ...
5
votes
1answer
210 views

Was job control supported in UNIX V7 or earlier?

Linux supports job control, i.e. you can start a process in the background, or make a foreground process run in the background, or make a background process run in the foreground, etc. Did any V7 or ...
10
votes
1answer
1k views

Why do many JiffyDOS users install a toggle switch to disable it?

For those that don't know, JiffyDOS is a ROM replacement for a Commodore 64 (and 128, I believe) and its 1541 disk drive. This ROM replacement provides OS shortcuts, faster load times, etc. I've ...
6
votes
2answers
457 views

First flat-panel display technology capable of 640x480

What was the first display technology capable of creating a flat-panel display with 640x480 resolution? (And reasonable size, say 12" to 14".) As far as I can see, three flat-panel display ...
14
votes
4answers
1k views

Did the Intel 8086/8088 not guarantee the value of SS:SP immediately after RESET?

I'm poking at the Intel 8086/8088 (iAPX 86/88) User's Manual, which states on page 2-29 (PDF page 48), table 2-4, CPU State Following RESET, that the state of the CPU after the RESET pin rising ...
8
votes
1answer
257 views

Grid Compass - why such a small display?

The Grid Compass, released in 1982, was arguably the world's first full-fledged laptop, whose only glaring deficiency to modern eyes is the small display, 320x240 with physical size to match, ...
7
votes
2answers
842 views

How early could plasma screens be used in laptops?

Back in the eighties, batteries weren't yet at the point where they could run a laptop with similar computing power to a desktop. If you wanted that much computing power, you just accepted that your ...
23
votes
2answers
2k views

How did MS-DOS assign drive letters in the case of more than two floppy disk drives?

The IBM PC BIOS had provisions for up to four floppy disk drives, by virtue of returning the number of floppy disk drives in a two-bit field plus a none/some flag (allowing for reporting values of 0, ...
18
votes
1answer
934 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) ...
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 ...
8
votes
1answer
357 views

Price of early color monitor versus TV

Some computers in the seventies and eighties had the option of output to either a TV or a dedicated monitor. Suppose repurposing an existing TV isn't an option and you are going to be buying a screen ...
8
votes
2answers
383 views

First computers to support Japanese script?

What was the first computer to support Japanese script, not just as a toy demo, but at a level where you could actually use it to get a day's work done with Japanese documents? And how did it do it? I ...
24
votes
4answers
3k 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 ...
21
votes
3answers
2k views

What's the TUBE interface of the BBC micro all about?

I keep reading of the BBC micro's tube interface that was apparently designed as a co-processor interface to the 6502. I would be interested in what were actual applications of this interface and ...
17
votes
2answers
1k views

68000 and memory access speed

On the one hand, I get the impression that memory chips around 1980 could be accessed no faster than 2 MHz. On the other hand, the 68000, introduced in 1979, had a typical clock speed of 8 MHz. How ...
8
votes
1answer
492 views

Typical mid-scale business computer system of the late 70s

What was the most common business computer system of the late 70s, just before the Apple II and CP/M really started proliferating? For concreteness, let's say we are talking about a U.S. company on ...
14
votes
2answers
2k views

How does the Kickstart ROM load and start workbench?

As I understand, on the Commodore Amigas, the kickstart copies itself into a region of memory which is later made read-only. Does kickstart also copy workbench into this region? How does kickstart ...
7
votes
1answer
432 views

Which memory management is easiest to program - CoCo 3 or C128/Apple //e? [closed]

As the 8-bit systems hit their peak in the mid-1980s, breaking the 64K barrier was all the rage. Commodore, Apple, Atari, and Tandy all shipped new 8-bit machines that came standard with 128K. Of ...
12
votes
9answers
902 views

Do retro-microcontrollers exist?

I'm trying to learn the fundamentals of computer architecture (more here), and it occurred to me that a retro version of an Arduino or Raspberry Pi could be useful for that. Does such a thing exist, ...
17
votes
5answers
2k views

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 ...
11
votes
6answers
878 views

How can I convert Epson escape codes to a more usable format?

I have many GWBasic programs peppered with Epson-specific escape sequences (ESC/P). Unfortunately I no longer have any printers that support these escape sequences. Is there any way I can convert ...
12
votes
1answer
291 views

Xerox Parc and the three-button mouse

The original GUI invented at Xerox Parc, used a three-button mouse. What did each of the three buttons do?
3
votes
1answer
208 views

Trying to open IBM FILING ASSISTANT in DOSBOX, or other? [duplicate]

How does one get a program like a word doc onto MS DOS to begin with? I have a set of files that are backups, only one with .exe that is from an ancient word processor and would eventually like to ...
0
votes
3answers
733 views

Does anyone have the source code of an early program written in Assembly? [closed]

I am interested in looking at the source code of any program that was written in Assembly just about when the Assembly language was invented. If anyone have a source code for such a program, please ...
11
votes
1answer
1k views

What ended the Sony console partnerships with Sega and Nintendo?

Sega and Nintendo were the dominant players in the console market at the end of the 1980s and into the 90s. By early in the next decade, Sony shipped the PlayStation 2, leading Sega to exit the ...
8
votes
1answer
130 views

cbm prg studio for the Amstrad

CBM prg studio is brilliant. I have searched Google for a version (or something similar) for the Amstrad CPC 464, to no avail. Does anyone know of one?
5
votes
1answer
187 views

Amstrad CPC 464 tape deck loads, but makes grinding scratching noise

I'm concerned about an Amstrad CPC 464 tape deck, which loads, but makes grinding scratching noise while rewinding, fast-forwarding and play. Sometimes it does load silently, but after a subsequent ...
8
votes
1answer
306 views

How did WebTV (MSN TV) work

Wikipedia says: The WebTV product was an adapter that allowed a television set to be connected to the Internet, primarily for web browsing and e-mail. The setup included a web browser, a corded or ...
11
votes
1answer
605 views

What is the proper way to test the PSU output for a Commodore 128D?

This question is directly related to comments on the more general question and answer here. The Commodore 128D and 128D-CR have an internal PSU that can be readily and safely disconnected from the ...
39
votes
1answer
2k views

What precautions to take when powering on old computer for the first time in years

I have a Commodore 128D that hasn't been powered in about 15 years. I want to begin using it again. It has been stored in cool dry places like attached garages, in a cardboard box. I hope this ...
5
votes
0answers
180 views

Manual for DIAGNOSTICS II V1.2 - CPU TEST SUPERSOFT ASSOCIATES

I am building a 8080 emulator. I found some useful test suites here. The emulator passes the first test suite (8080/8085 CPU Diagnostic, version 1.0, by Microcosm Associates), but not the second ( ...
8
votes
1answer
795 views

128-bit floating point

IEEE 754 defines 128-bit floating point, though perhaps in a three-way chicken and egg problem, it's rarely supported by hardware, rarely supported by compilers, and rarely used. Have there been, ...
12
votes
2answers
483 views

Is this machine the EDVAC, MANIAC, or IAS?

See the image. Different sources claim that this machine is the EDVAC, MANIAC I, or IAS. For example, the Wikipedia page on John von Neumann has a picture of him and J. Robert Oppenheimer standing ...
12
votes
1answer
282 views

What is the difference between i8080 and i8080a?

There is some info over the net regarding 'some i8080 bugs were fixed in i8080a', but the exact bugs and differences are not usually disclosed. So, what is the exact difference between i8080 and ...
8
votes
1answer
189 views

How to disable existing, unknown, password from AppleTalk on MacOS 7/8?

My Grandparents computers are connected to each other via an ethernet cable, and communicate via AppleTalk. One of the computers is an iMac G3 with Mac OS 8 and the other is a "SuperMac" from the ...
6
votes
3answers
1k views

Atari 800XL, black screen on power on - how to diagnose the problem?

I've got an atari 800 XL that is broken - when I power on, there's no reaction. It seems there is at least something sent to display, as TV detects a signal, and turns full black. The chips are ...
17
votes
1answer
2k views

Was it possible to get more than 8 sprites per scanline on an Amiga with the copper list?

I've read in the past that it was possible to overcome the 8 sprites per scanline on the Amiga (OCS) using the copper list. However, I can't seem to find any actual references to what may have used ...
15
votes
3answers
3k views

6510 clock rate of C64: Why was it considerably slower than the 6502 of the Atari 800?

According to Wikipedia, the Atari 8 bit series had a 6502 running at ~1.8 MHz. Why was the clock speed of the 6510 for the C64, which was designed a couple of years later, considerable slower? Was the ...
12
votes
6answers
2k views

Memory-limited workloads

I'm trying to figure out whether computing workloads, particularly those related to science and engineering, have historically been limited by memory or CPU. (By the former, I mean not memory access ...
7
votes
2answers
552 views

Can I power a z180 with 3.3v [closed]

I'm planning to buy a Z8018006PSC. A z180 CPU (which I found is compatible with the z80 and has some advantages, for instance, able to address up to 1MB of RAM). I'm planning to use it together with ...
21
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 ...
4
votes
2answers
394 views

Cost of tape backup in 1980

How much did it cost in 1980 to buy a tape drive capable of backing up 5 megabytes of data? Both for the drive itself and per tape? (If that exact data is unavailable, I'd be interested in something ...
19
votes
1answer
776 views

Which computers had features added purely for tax reasons?

I was recently reading about the Amstrad CPC 472, which was a CPC 464 with an extra, unusable 8KB of RAM added to avoid Spanish import fees on computers with 64KB or less. Did any other computers have ...
3
votes
0answers
215 views

How many CP/M machines ever shipped? [closed]

How many machines for which CP/M was the primary operating system (so not counting the Commodore 128) ever shipped? I would also be interested in knowing how many S-100 machines ever shipped. I get ...

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