1
vote
1answer
46 views

Labor input for manufacture of early personal computers

In the early days of personal computers, manufacturing was not as automated as it later became, and a factory would often consist of people sitting at tables placing components by hand. I'm ...
9
votes
1answer
481 views

What was the reason for the ZX Spectrum's display bitmap layout?

I had a ZX Spectrum 48KB, whose display was a 256*192 monochrome bitmap (plus separate per-block color attributes). I remember the display bitmaps scan lines were laid out in memory in a weird way - ...
6
votes
1answer
194 views

Why did MS-DOS choose percent symbol to designate variable?

I couldn't find anything but is there any reason for choosing % over $ like in *nix shells?
8
votes
2answers
136 views

What was “whole-value computation” in early real-time systems?

I've been reading Achieving Accuracy: A Legacy of Computers and Missiles by M. W. McMurran, who helped develop the Autonetics D-17 guidance computer for the Minuteman ICBM in the early 1960s. For all ...
17
votes
3answers
5k views

History of Ctrl-S and Ctrl-Q for flow control

Which OS was the first to use Ctrl-S and Ctrl-Q on the console for pause and continue? I first discovered Ctrl-S in IBM PC DOS 1.1.
12
votes
0answers
175 views

Identify this front panel

It was in the movies "Star Trek II: The Wrath of Khan" (1982) and "Serenity" (2005). It resembles the Honeywell 6000 series but I can't find a photo of it that matches exactly. Could it be a custom ...
3
votes
0answers
67 views

Which DOS for a TRS-80 Model 4P?

Looking at the TRS-80 Disk Software Page, there's a rather extensive selection of DOS options that seem to work with the 4P and also claim high compatibility with the Tandy "TRSDOS" option. ...
8
votes
1answer
142 views

What are the differences between the various 36-bit computers from DEC?

I want to ask about the PDP-6 PDP-10 various implementations KA-10, KI-10, KL-10 DECSYSTEM-20 What are the differences between these? I'm not that interested in architectural differences, cache ...
5
votes
2answers
173 views

How to protect a ZX Spectrum mainboard from “ageing”?

I have some ZX Spectrums, and in some of them I observe a kind of "disintegration" process of the main board. The connectors break away etc. During the tests one of the boards burned out :(. How can ...
2
votes
2answers
152 views

Cost of a chiclet keyboard

Early personal computer keyboards could be membrane (Atari 400, ZX80, ZX81), chiclet (PET 2001, ZX Spectrum, Oric, IBM PC Jr) or mechanical/full-travel (later PET, Apple II, TRS-80, Vic-20, and most ...
5
votes
2answers
344 views

Membrane keyboard robustness

Some early computers used a membrane keyboard (ZX80, ZX81, Atari 400), or semi-membrane with minimal keys (ZX Spectrum). This is because it was cheaper than a mechanical keyboard. Intuitively I would ...
12
votes
2answers
1k views

Why does the ZX80 not produce a steady display signal?

As Tommy pointed out in my question about BASIC tokens on the ZX Spectrum, the ZX80 is a computer which does not produce a signal which is displayed steadily on the TV. It looks to me as if the CRT is ...
6
votes
8answers
3k views

Can one isolate processes on a 8086?

I've read that modern OSes rely on hardware-powered process isolation to prevent processes (and/or users) from clobbering each others' RAM. But on Intel processors, this hardware was first included in ...
26
votes
5answers
7k views

How did Apple fail to tap the business and scientific markets?

Currently reading an excellent book called Blue Magic: The People, Power and Politics Behind the IBM Personal Computer, which is just what it says on the tin; highly recommended to anyone who wants to ...
4
votes
1answer
125 views

IBM AS/400 connection via SNASW on Cisco Router

TL; DR: How can I connect two old AS/400 machines via SNA when the only transport mechanism between the physical locations is IP? AnyNet isn't an option, see below. A friend of mine and I have two IP ...
3
votes
2answers
182 views

First (3rd Party) Application-Agnostic Home Computer or OS for such

What was the first home computer and file system that allowed users to choose freely between 3rd party applications? I was under the impression that early PC (manufacturer) bundled their own ...
58
votes
10answers
13k views

How was C ported to architectures that had no hardware stack?

Thinking about machines such as the PDP-7, PDP-10, CDC-160 and so on1, these are machines which do not have a stack pointer which can quickly and easily change to point to a new stack frame, like the ...
6
votes
4answers
366 views

Early Basic memory management

Can anyone verify or correct my memory here? Long ago, I had access to a Commodore PET which I think had 8kB of memory. Also slightly less long ago, I had a Commodore 64 with its "elephatine" 64kB. ...
21
votes
7answers
3k views

What were the early PC applications requiring a hard disk?

I had to wait about 5 years before hard drives (HDs) became affordable enough to begin moving off of floppies. During this time, I remember my desire for an HD being based on convenience. All the ...
12
votes
6answers
2k views

MITS to Dell: the mail order gap?

In 1975, MITS advertised the new Altair (not actually the first personal computer, but close enough that many historical accounts proclaim it as such) by mail order, and it sold very well by the ...
4
votes
0answers
101 views

How to use IIgs enhanced graphics modes in AppleSoft BASIC with System 6?

There are many packages that let you use the enhanced graphics modes of the IIgs in AppleSoft BASIC. However most packages like Iconix do not like System 6 so they have to run off disks and not the ...
6
votes
0answers
163 views

How was the Intel 80486 debugged? [closed]

How was the Intel 80486 (from 1989) debugged? I'm assuming it was written in some HDL language, like Verilog. However, how was testing and debugging of the CPU carried out? Were there several steps ...
2
votes
1answer
221 views

How does the SNES (Super Nintendo) calculate the address of a character?

The SNES has a PPU (Picture Processing Unit) which comprises VRAM, OAM (Object Attribute Memory), and CGRAM (Color Graphics/Palette RAM). These are used to represent tiles, tile maps; attributes for ...
8
votes
3answers
245 views

How specific was the Apple II floppy disk controller?

One of Wozniak's greatest inventions was the Apple II floppy disk controller, which allowed Apple to avoid going the Atari/Commodore route of making each disk drive a computer in its own right; ...
2
votes
2answers
248 views

FCC RF limits and wire transmission speeds

As I understand it, in the early days of personal computers, strict FCC limits on RF emissions, were a factor limiting the speed at which data could be transmitted over wires, but I'm trying to ...
1
vote
3answers
188 views

A fatal exception 0E has occurred at 0028:FF02847B Installing Windows 98 SE

I get A fatal exception 0E has occurred at 0028:FF02847B after trying to install windows 98 se on an hp pavilion zt3000. It does this right after is says searching for plug and play hardware.
2
votes
0answers
66 views

PET game, enemies attempt to break through several concentric sets of walls

I'm looking for another PET game, which I cannot find on various sites. It was one of the earlier ones - it was available when I first got access to the PETs circa 1981/82. The user starts in the ...
3
votes
0answers
114 views

Where did /usr/mdec come from?

On UNIX, the boot code is traditionally found in the directory /usr/mdec. Some modern UNIX variants keep this tradition up (e.g. OpenBSD) while others have changed the directory layout (e.g. FreeBSD)....
10
votes
1answer
370 views

The almost-was Atari IBM PC

One of the more remarkable events in the history of personal computers was IBM contemplating basing their PC on Atari technology. That this was seriously considered, everyone agrees, but it's hard to ...
7
votes
2answers
555 views

How compatible is the Leningrad clone with the “original” ZX Spectrum?

In Leningrad they developed a clone of the ZX Spectrum, replacing the ULA by some TTL logic. Some of my speculations: In the USSR, the analog TV sets used SECAM, not PAL, so I imagine that the ...
8
votes
3answers
1k views

Visible resolution of C64 video output, including borders

The VIC-II in the C64 outputs 320x200 pixels inside the borders. What is the full visible resolution including the borders? To clarify, I am interested in the full screen size in units of normal ...
5
votes
1answer
235 views

Who established the original F1 desktop BIOS key and why did laptops use a different key?

It seems early on IBM, MS, and DOS clones established a standard of holding the F1 key down during boot to access the BIOS setup. Yes there were a few much less common combinations that used the DEL (...
7
votes
1answer
404 views

How big was WordStar 1.0?

How big was the original CP/M version of WordStar? As in, the size of the program itself? Presumably it was in the low tens of kilobytes (I don't think it's possible to cram a practical word processor ...
8
votes
1answer
312 views

How did the Commodore PET 80 column display work?

Some variants of the Commodore PET (e.g. the 8000 and 9000 series, as well as some other versions with an aftermarket add-on) produce an 80x25 character display. Their character set is fixed in ROM ...
23
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 ...
7
votes
1answer
204 views

How were Microsoft GW-BASIC “protected” files encoded?

Microsoft GW-BASIC on IBM compatibles allowed flags to the SAVE command, to indicate the manner in which a file should be written out. As I recall, it allowed for no flag to write a standard ...
8
votes
3answers
2k views

Daisy-chained cassette drive?

Early microcomputers sometimes supported several peripherals in a 'daisy chained' arrangement, i.e. instead of the computer having several ports, one per peripheral, it had a single port, which each ...
21
votes
4answers
7k views

Why did ones' complement decline in popularity?

Many early computers use ones' complement to represent some kind of signed integer. Examples include the PDP-1, the CDC-6600, and many other popular computers. The C standard is obviously written ...
6
votes
1answer
179 views

Total weight of the CDC 7600?

I'm doing some research on the CDC 7600 supercomputer. I'm trying to find at least a general guess on the overall weight of the machine, preferably including the necessary cooling equipment. I know it ...
5
votes
6answers
293 views

What Video Chips/Video generation techniques are usable for the Z80?

I'm building a Z80 home computer and I need color graphics for it similar to other home computers such as the C64. I thought that, like Motorola or MOS, Zilog would have a peripheral chip dedicated ...
2
votes
2answers
291 views

What made channel bleed so bad over coaxial cable?

Using coaxial cable, there was a really bad channel bleed - as shown in this video, putting a NES on channel 3 caused distortion to the static on channels 2 and 4-7. This distortion was so bad, you ...
3
votes
2answers
217 views

When did the Macintosh start using four (or more) layer PCB's?

I'm assuming (but do not really know) that the original Macintosh used a two layer PCB. So my question is, when did the Macs start using more complicated boards with four (or more) layers? For ...
10
votes
4answers
2k views

What are the rules for Applesoft BASIC formatting for code?

What are the rules for Applesoft BASIC formatting for code? I've been doing some BASIC coding and noticed that: 10 input "some question?"; name$ Will be reformatted as: 10 INPUT "some question?";...
10
votes
2answers
304 views

What modern image editors support non-square pixels?

Almost all old home computers tend to offer non-square pixels, from wide-pixel graphics modes on the C64/CPC/BBC Micro to CGA's weird not-quite-square 320x200 mode with a pixel aspect ratio of 5:6. ...
1
vote
2answers
144 views

CRT contrast issue: light grey on dark grey

This is on an IBM 5154. Dark grey next to light grey produces a white line between the two. This is noticeable on a color bar test, but is even worse in SimCity (making the text impossible to read). ...
5
votes
1answer
254 views

1980's ROM used which exp(n) algorithm?

In 1980's ROM (Apple IIe, Commodore 64, VIC-20, ...) which algorithm is used to compute exp(x), and where do the coefficients below come from? (Chebyshev, Remez, Pade, ...) .byte $71,$34,$58,$3E,$...
21
votes
3answers
1k views

Why use repeated STZ instructions with the same operand on the 65C816 for the SNES (Super Nintendo)?

Please consider the code in Super NES Programming/Initialization Tutorial/Snes Init. Here is an excerpt: stz $2113 ; Plane 3 scroll x (first 8 bits) stz $2113 ; Plane 3 scroll x (last ...
3
votes
2answers
262 views

How were individual bit planes scrolled on the Amiga (OCS)?

Back in my early Amiga days (A500), I remember coding simple demos that would use the dual-playfield mode and scroll them around (at a sweet 60FPS). It was pretty trivial to do with languages like ...
10
votes
2answers
488 views

What is the history of the PDP-11 MARK instruction?

The PDP-11 MARK instruction was intended to be used as part of the standard PDP-11 subroutine return convention. MARK facilitated the stack clean up procedures involved in subroutine exit. To use it, ...
6
votes
1answer
149 views

DEX: How does a 2-Cycle instruction affect RCL outputs AFTER it completes?

I (as so many people before me) am developing a software simulation of the 6502, mostly based on the often cited block diagrams and several other sources of information. Basically all the components ...

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