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Questions tagged [8-bit-microcomputers]

For generic questions about 8-bit microcomputers. For specific computers please use the appropriate specific tag.

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12 votes
11 answers
3k views

Were there any 8080 computers that used a bitmapped display?

Does anyone know of any bitmap-based 8080/8085 (or, failing that, Z80) computers? Background: In the late 70s and early 80s, there were a few hobby computers with bitmapped displays. For example, the ...
7 votes
1 answer
2k views

The proper way to shift a byte using a Z80

In a nutshell, why can I not shift a byte using this way? LD A, 11110000b ; I want this to be 00001111b LD C, 4 SRA C OUT (0), A ; doesn't give correct number What is the proper way of shifting a ...
8 votes
2 answers
909 views

What were MECC's specifications for a school computer in 1978?

It is well-known that one key moment for Apple was selling 500 Apple IIs to the Minnesota school system in 1978. I came across this video which discusses the background to that, including a reminder ...
3 votes
2 answers
385 views

Can anyone tell me more about flippy games?

I remember having a number of Mastertronic tape games for the Amstrad CPC 464 that could be used on a Spectrum too by using the other side of the tape. These were called flippys I believe. Was this ...
16 votes
6 answers
3k views

Which 8 bit computer could display the most colors?

Which 8-bit computer could / can display the most colours on screen? Please take into account undocumented/newly discovered video modes and other hacks. For example, static sprites supposedly allow ...
1 vote
0 answers
230 views

Why is my crystal oscillator (4 pin DIP 4 MHz unbranded from ebay) producing unusable clock signal waves? [closed]

I was trying to make a Z80 computer (I tried with Intel 8088 and failed because I am dumb) so I bought a 4-pin 4 MHz crystal(from here:ebay listing) and I tried to check the crystal by connecting it ...
7 votes
6 answers
1k views

Would some BASIC interpreters for microcomputers be considered operating systems?

As software for micros developed, you could use the BASIC interpreter just to CLOAD and RUN assembly language programs. Those might call BASIC ROM routines (say, for converting ASCII input to binary ...
14 votes
1 answer
2k views

How did Altair 8800 interrupts work?

I'm playing around with building an Altair 8800 emulator in my free time in C#. I've read through the Operator's Manual many times in the past, and I'm refreshing my memory of late. I'm struggling to ...
23 votes
21 answers
6k views

8-bit home computers without BASIC

All the 8 bit home computers I'm aware of, had BASIC in their ROMs. A notable exception was Jupiter Ace, a British home computer which used Forth. Were there any other 8-bit home computers that came ...
80 votes
14 answers
19k views

Back in the late 1980s, how was commercial software for 8-bit home computers developed?

When hobbyists wanted to write software for e.g. the Commodore 64, they either used the built-in BASIC interpreter (with all its limitations) or some native tools, like compilers for other languages ...
14 votes
8 answers
3k views

Copying tapes "back in the day"

Back when I had a ZX Spectrum 48K, I had a friend that had a 128K and we would swap games for the weekend from time to time. We did try and make duplicates of the tapes (yes, I know, but we were ten ...
34 votes
8 answers
4k views

What made some 8-bit BASIC interpreters especially slow?

Most 8-bit systems had a BASIC interpreter that ran at a rate roughly commensurate with the CPU type, speed, memory bandwidth and interrupt status. Some systems, however, had interpreters that ran at ...
7 votes
1 answer
321 views

Is there really any implementation of a Ada compiler/cross-compiler/interpreter for 6502?

I found some Ada compilers for CP/M machines but no luck for 6502-based C64/Apple II/BBC Micro. I'm not sure if Abacus Ada on C64 exists or how much a subset it implements for Ada. There is, though, ...
9 votes
4 answers
1k views

Testing "8-bit readiness" with an emulator or pre-packaged kit

I'm working on a project that intends to implement a dynamically typed language on 8-bit systems. (That is, a CPU with 16-bit pointers and a maximum of 64 kB of RAM. Some language tricks are involved, ...
9 votes
3 answers
780 views

BASIC : POKE and PEEK prohibited on the same line?

Having been raised on an 8-bit Commodore, I was never afraid of PEEKs and POKEs. I remember trying to accomplish something on a computer, in BASIC, using PEEKs and POKEs, and discovering that this ...
8 votes
1 answer
423 views

Looking for an 8-bit microcomputer with a hardware-accelerated database

In some old video on YouTube a few years ago, I noticed a curious computer from the end of the 70s - early 80s. In the rack (half height), typical of minicomputers of those years, there was a 14" ...
24 votes
4 answers
2k views

Which (micro) computers were dominant in Australia and New Zealand in the 1980s?

Australia and New Zealand are somewhat unique among large, developed, economies because they bridge the culture of (mostly) the West with the geography of the East. I am curious how this may have ...
1 vote
2 answers
176 views

Dump Mask ROM on MAB8421

I am trying to find a way to dump the rom contents of several MAB8421 microcontrollers. I know that on many 8048 MCUs, you can use the external access pin to dump the rom, but the 8421 doesn't have ...
27 votes
8 answers
6k views

Why did 8-bit Basic use 40-bit floating point?

Nowadays floating point is usually either 32 or 64 bits, sometimes 16, occasionally 128. But of course, the Basic interpreters on the 8-bit machines, having to implement floating point in software ...
33 votes
1 answer
2k views

When and where did the $ convention for hexadecimal literals originate?

I found this question asking about the origin of 0x to denote hexadecimal to be interesting. However, when I cut my teeth programming on 8-bit 65xx systems in the early 80's everything I saw used a $ ...
28 votes
9 answers
6k views

Fastest 8-bit microprocessor for multiply-accumulate?

I'm wanting to identify which 8-bit microprocessor would have the best performance for a multiply-accumulate operation. By "operation", I mean the minimal implementation for 16-bit operands ...
7 votes
1 answer
322 views

Anyone have the 1975 edition of "An Introduction to Microcomputers, Vol 2"?

I'm looking for references to the EA9002, an ill-fated design if there ever was. Practically the only place I can find it detailed is Osborne's Introduction to Microcomputers, where it was chapter 11 ...
3 votes
1 answer
376 views

What was the first personal computer store in Australia?

In the US, the personal computer revolution was kickstarted by mail order, which is the channel through which the Altair was sold. However, it did not take long for the new industry to be augmented ...
8 votes
1 answer
417 views

What was a MicroAce?

I am familiar with the original ZX80 and its "cousin", the Jupiter Ace, a similarly specc'ed machine but running Forth rather than BASIC. However, a colleague at work stated that there had ...
13 votes
14 answers
3k views

Emulators running on 8-bit personal computers

Were there emulators running on 8-bit computers (preferably "mainstream" personal ones), available to general public (as opposed to in-house developers only)? I am mostly after emulators ...
22 votes
5 answers
4k views

How did old computers address far more than 64K of memory despite only having a 16 bit address bus?

I have an old Sharp PC-G830 pocket computer from the '80s that has 32K of RAM and 256K of ROM. I also have a simple single board computer I built with 128K of RAM and a few megabytes of ROM from a ...
10 votes
3 answers
2k views

Was there ever a microcomputer with a full-size keyboard and a hex numpad?

I'm aware of some early/super hobbyist microcomputers that came with ONLY a hex numpad (that is, no letters beyond F/no punctuation). I'm also aware of home microcomputers that had the usual decimal ...
2 votes
4 answers
486 views

Cheapest way to store and load small dataset in the 80s?

An extra, costly floppy drive would overkill when transferring a page of letter, storing game level data, or distributing a piece of BASIC program, and non built-in ones have to be paid. A tape ...
0 votes
1 answer
174 views

How the technology keeps improving [closed]

How does the technology keep improving despite having everything discovered already? I mean the same sized chips and electronics are used from year to year but with every new version of the main board ...
33 votes
1 answer
8k views

Did John Carmack really invent "Adaptive Tile Refresh"?

John Carmack is credited with making fast-paced arcade games like Commander Keen possible on an IBM-PC that had no specialized graphics controllers suited for those, thanks to the "Adaptive Tile ...
19 votes
7 answers
1k views

Did any microcomputers back in the day accelerate standard-cassette performance

Many commonplace cassette recorders in the 1970s and 1980s were capable of reading or writing two tracks at once (stereo). While that wasn't universal (portable cassette recorders were often monaural,...
9 votes
0 answers
243 views

Systems that used the Rockwell R65C00/21 or R65C29

The Rockwell R65C00/21 and R65C29 are described in an October 1984 datasheet ("R65C00/21 dual CMOS microcomputer and R65C29 dual CMOS microprocessor," Document no. 29651N64, rev. 2) which is ...
26 votes
9 answers
5k views

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? I'm reverse engineering a firmware binary for a device built around a Hitachi 6303 processor, manufactured in 1983. Even ...
4 votes
2 answers
338 views

Looking for NEC RA87 “Relocatable Assembler Package”

I admit, I am pushing my personal envelope (punching above my weight, beyond my pay-grade etc. etc.) on the trailing edge of technology. So please be kind! I would like to write new firmware for a NEC ...
28 votes
10 answers
7k views

Why did 8-bit computers choose BASIC dialects as "de facto" command-line interface, instead of contemporary Shell/Lisp dialects?

While all three clans of languages predated 8-bit computers, they shares features like 1) imperative programming, 2) English-alike keywords, 3) Prompt-Command-Parameters pattern interface. Why was ...
18 votes
4 answers
2k views

How was the main mechanic of the game Qix implemented?

Qix was a quite unique Taito arcade video game that saw ports to nearly any home computing platform of its time. At first glance, the game mechanics seem to be targeted at low-performance hardware - ...
8 votes
3 answers
654 views

Uh, oh, I've woken up in 1973. Can I get a job in computing? [closed]

I've woken up in 1973. Until I can figure out how to monetize my knowledge of coming political, economic, and social trends, I need to support myself somehow. So... I walk into one of the major ...
15 votes
4 answers
3k views

Benchmark test that was used to characterize an 8-bit CPU?

I was curious if there was a benchmark test that was available to compare CPUs that are 8-bit. People always like meaningless analysis to justify some decision, and I was curious if there was a ...
3 votes
1 answer
332 views

What bug in first version of game Karateka for Apple 2e cause this game reset in Apple 2c?

If I try to start the first version of the game Karateka for Apple IIe on an Apple IIc, the Apple IIc will restart after reading the game from disk after a few seconds. Later versions of Karateka for ...
23 votes
11 answers
5k views

Did any European computers use 10-line fonts?

Most 8-bit computers implemented hardware text mode, and most of those used 8x8 fonts. This was logical for American computers; the title safe area on NTSC is about 200 scan lines; font height 8 gets ...
10 votes
2 answers
978 views

Did any 8-bit CPUs use dynamic memory for registers?

According to https://jamiestarling.com/project-8088-the-8088-cpu-pinout/ One thing to note – the 8088 registers are made from dynamic memory cells – they have to be refreshed. The minimum clock speed ...
-3 votes
2 answers
505 views

How can 8bits = 1byte but also = 255 bytes at the same time? [closed]

I don't understand why 8bits is defined as being equal to 1byte or 1octet but at the same time the maximum capacity of an 8bit bus or 8bit databus would be 255 bytes because 128 64 32 16 8 4 2 1 1 1 ...
9 votes
1 answer
1k views

What kind of 256 color palette did the Enterprise 64/128 have?

The Enterprise 64 or 128 Home Computer apparently had a palette of 256 colors. However, that is pretty unusual and doesn't fit evenly into the typical 3 channels for RGB. Wikipedia doesn't provide any ...
6 votes
2 answers
1k views

What was the first microcomputer capable of working with Japanese kanji?

Apparently the first microcomputer capable of working with the Chinese language in Chinese characters was the Microprofessor II (or MPF-II-C), a Taiwanese Apple II clone from 1982. Now I'm 99% sure ...
2 votes
1 answer
132 views

TMS9918ANL question

I am working on setting up a TMS9918ANL Video Display Processor. I was wondering if there is any way I can test to see if it is working without having the DRAM hooked up (I have a while before the ...
20 votes
4 answers
6k views

Were there any 8-bit CPUs with 24-bit addressing?

Or was that something that didn't appear until later CPUs (around the time of the 286 maybe)? Also, how would I go about researching this on my own? It's not exactly something I can look up on ...
3 votes
4 answers
959 views

"SAP" microcomputers vs real microcomputers

In Paul Malvino's "Digital Computer Electronics", he labeled 3 theoretical microcomputers which he called the SAPs or "Simple As Possible"s. The point of these 8-bit microcomputers was to teach ...
26 votes
6 answers
12k views

Can x86 processors run 8-bit applications?

I was wondering if it is possible to run 8-bit applications within QEMU. I know that the x86 architecture can run 16-bit applications, but can it also run 8-bit applications?
21 votes
9 answers
7k views

Intel 8080-based home computers

I'd like to build an FPGA replica of a home computer based on the Intel 8080. I am not looking to design my own computer, since I would like to tap into an existing software base. Were there any ...
30 votes
2 answers
5k views

Zilog Z80 freezes while binary counting up to 65 536 (2^16)

A few days ago, I got Z80A CPU from eBay. So I tried to run it with classic 555 timer as a clock signal generator. I connected the 8-bit data bus of the CPU to the ground to "simulate ROM" (00 for NOP)...