89
votes
Back in the late 1980s, how was commercial software for 8-bit home computers developed?
It varied. There was no single method. Some people used assemblers on the target machine, others used cross-development tools.
As an example of a large product for an 8-bit machine, I worked on the ...
- 13.8k
56
votes
Accepted
Zilog Z80 freezes while binary counting up to 65 536 (2^16)
There are many issues here.
As it is already said in comments, decoupling capacitor is a must!
555 (non-CMOS) timer output is very much like the output of TTL ICs, however Z80 requires a firm logic ...
- 10.9k
56
votes
Accepted
Did John Carmack really invent "Adaptive Tile Refresh"?
John Carmack almost certainly was the first to use the hardware scrolling capabilities of the EGA specifically, together with efficient tile and sprite drawing and erasing algorithms to create a slick,...
- 12.7k
55
votes
Why did 8-bit computers choose BASIC dialects as "de facto" command-line interface, instead of contemporary Shell/Lisp dialects?
People nowadays think of BASIC as something lesser and generally tied to puny microcomputers, but BASIC was the language of choice for many scientific, engineering and business computers in the 1970s. ...
- 231k
53
votes
Accepted
How was the first assembler for a new home computer platform written?
Gates and Allen used remote terminal access to a minicomputer (Harvard's DEC PDP-10) to cross-assemble, and simulate, their implementation of BASIC for the Altair 8800. Commodore Basic (for the 6502) ...
- 8,317
49
votes
Accepted
Fastest 8-bit microprocessor for multiply-accumulate?
And sorry to nerd-snipe this, but of course the ideal candidate for a fast multiply-add is a Digital Signal Processor CPU, and nothing in your requirements says that DSPs are excluded. It will be also ...
- 29k
47
votes
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Why did 8-bit Basic use 40-bit floating point?
The floating-point routines for Microsoft BASIC were written by Monte Davidoff in 1975, originally for the Altair, which used an Intel 8080 CPU. The source code had been lost for years, until Bill ...
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45
votes
How was the first assembler for a new home computer platform written?
As someone who did it....
We wrote an assembler for an 8080, as there was nothing affordable from Intel.
We wrote it in ALGOL 60, if I recall, and ran it on a mainframe.
the first thing we ran ...
- 551
36
votes
Accepted
How common was programming in C targeting 8-bit processors in 1983?
How often was C used to program firmware for 8-bit processors in the early 80s?
It would have been a rather unusual choice in 1983. True, C was slowly creeping in, but only on 'big' machines and 16 ...
- 231k
34
votes
Back in the late 1980s, how was commercial software for 8-bit home computers developed?
This had a lot of drawbacks, like the limited screen size, the slow Disk I/O, the limited RAM needed for the tools and your own code, etc.
Those are just drawbacks of having a slower or less capable ...
- 39.5k
34
votes
Which 8 bit computer could display the most colors?
Considering only 8-bit CPUs, I think the answer is the Fujitsu FM-77 AV40, which can display any 64,000 colours from a palette of 262,144 with a 320×200 resolution (the 64,000-colour limit is tied to ...
- 127k
33
votes
What made some 8-bit BASIC interpreters especially slow?
"Atari BASIC: The Good, the Bad, and the Ugly" is an excellent summary Atari BASIC's advantages and weaknesses. To answer the Atari half of your question:
How did it get so slow? Basically ...
- 3,772
32
votes
Accepted
Unlicensed home computer ports of arcade games
To understand what was going on with licensed and unlicensed ports of popular arcade games in the 1980s, you have to understand two critical factors.
The video gaming culture of the time, and the ...
- 61.2k
31
votes
8-bit home computers without BASIC
One example of popular 8-bit computers without BASIC in ROM is the first three Atari 8-bit computers, the 400, 800, and 1200XL, which didn’t have BASIC built-in but on a separate cartridge.
Their ...
- 127k
30
votes
Accepted
Wiring a Zilog Z80
The MK 3880 Mostek CPU Technical manual (it's the Z80 implementation from Mostek) has a section called "Hardware implementation examples" which may help you.
Besides, the Thomas Scherrer Z80-Family ...
- 18.9k
30
votes
Accepted
How did old computers address far more than 64K of memory despite only having a 16 bit address bus?
I don't know details of the Sharp PC-G830 specifically but the technique used to address more than 64K with a 16-bit address bus is called "bank switching".
This involves setting up some ...
- 3,047
29
votes
Accepted
Why did 8-bit computers choose BASIC dialects as "de facto" command-line interface, instead of contemporary Shell/Lisp dialects?
If we're not talking about BASIC as a programming language, but the operational commands that surround it, then the answer is that they surely reimplemented the command structure of existing ...
- 36.9k
29
votes
Accepted
When and where did the $ convention for hexadecimal literals originate?
Short Answer:
Motorola used it for their 6800 and MOS (6500) inherited it from Motorola. After all, the 6500 team members came out of the 6800 project so they were already used to it.
Long Answer:
...
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29
votes
8-bit home computers without BASIC
(Please see as well other fine answers for more computers fitting the list)
I guess we can put them in four categories (in descending order of application):
Machines with Different Language in ROM
The ...
- 231k
27
votes
What made some 8-bit BASIC interpreters especially slow?
Commodore BASIC suffered from four major performance issues:
It stored numbers as text in the source, and had to parse numbers every time they were used.
Program lines are stored as singly-linked ...
- 371
26
votes
Accepted
What LISP compilers and interpreters were available for 8-bit machines?
To volunteer a few:
Acornsoft LISP. First released in 1982 on tape, disk and ROM chip for the BBC Micro and rereleased as a cartridge for the Acorn Electron in 1984; possibly related to the Apple II'...
26
votes
Why did 8-bit Basic use 40-bit floating point?
Using a 32 bit signed mantissa and 8 bit unsigned exponent has one major advantage: You can re-use 32 bit integer math functions for operating on the mantissa.
That re-use saves memory. It may even be ...
- 15.4k
25
votes
How was the first assembler for a new home computer platform written?
The same answer as everybody else, just with more detail:
What I mean: An assembler is not an application exactly trivial to write.
Oh, but it is. A "first" assembler on a platform simply reads ...
- 1,589
25
votes
Which microcomputer manufacturers developed their own Local Area Network systems?
One prime example is the Econet networking system designed by Acorn Computers.
Best known for their BBC Microcomputer and Archimedes systems, Acorn started with a range of modular rack-based ...
- 8,316
24
votes
Accepted
Were there any 8-bit CPUs with 24-bit addressing?
Were there any 8-bit CPUs with 24-bit addressing?
Not many. Most prominent and best fitting examples would be
WDC 65816 of 1983
Hitachi 64180 of 1985 / Zilog Z180 of 1985 (only 19/20 bit)
eZ80 of ...
- 231k
24
votes
Accepted
Benchmark test that was used to characterize an 8-bit CPU?
There are three primary benchmarks used during this period. They are not strictly "CPU" tests, but were often used for that purpose.
The almost unknown Rugg/Feldman suite from 1977. This ...
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23
votes
How was the first assembler for a new home computer platform written?
The 1974 Altair 8800 kick-started the industry but at the time offered no keyboard, no screen, just a bunch of switches and lights connected directly to the bus and a counter to help you input or ...
- 37.9k
23
votes
Back in the late 1980s, how was commercial software for 8-bit home computers developed?
So, nowadays, you'd have to be crazy not to use a PC and some nice cross-development tools when targeting these old machines.
To start with, I still like to use my IIgs (or IIc-plus) when coding for ...
- 231k
23
votes
Accepted
The proper way to shift a byte using a Z80
TL;DR:
Simply because SRA C doesn't shift A by the content of C, but shifts C right by one with keeping bit 7 (sign) static.
Z80 and shifting:
While the Z80 did add some nice new shifts and rotates, ...
- 231k
22
votes
Copying tapes "back in the day"
In theory, it is fairly simple duplicating a tape.
The problem with analog tape-to-tape copies is that sound quality lowers and spurious noises are also copied and more are generated into each new ...
- 2,777
Only top scored, non community-wiki answers of a minimum length are eligible