ATX-80 – ZX-80 computer clone with ATmega8 processor | Hacker News Reader

ATX-80 – ZX-80 computer clone with ATmega8 processor

breatharian.eu

95 pointsxkriva1124 comments

Nostalgia for the days of assembling your home computer.

My first home computer was a Sinclair ZX81. With the 16K RAM Pack which crashed the machine if it was wiggled even slightly - and now I have horrible flashbacks remembering a time when I spent a couple of hours typing in row upon row of hexadecimal (plus CRC check code for each line!) from the pages of a magazine to get a Space Invader type game on the ZX81. And then the RAM Pack crashed the machine before I could save to cassette tape - BOOM!

A high school friend of mine had a Compukit UK101 [0] which he assembled himself. Quite a quirky and bulky machine that was.

[0] http://www.computinghistory.org.uk/det/8099/Compukit-UK101/

I also started with ZX81. For a while, I didn't have a cable for tape recorder. A couple of magazines came with my ZX. Inside, there were some listings of games in BASIC. So, to play a game, a had to retype the code every time I restarted the computer. After a while, I started changing the code to see what will happen.

That's how I learnt to code.

Yep, it was a great time to be growing up as a kid wasn't it. All through those years of home computers. ZX81-->VIC-20-->C=64-->Amiga 500-->Amiga 1200 (I still have that one).

Progressing from BASIC to Z80 to 6502 to Motorola 68000 to C and so on. Learned Turbo Pascal and COBOL in college. Such nostalgia! :)

> Quite a quirky and bulky machine that was.

But apparently, unlike the ZX81, it actually had a proper keyboard, so there's that. ;)

Same! I saved up a long time to buy that ZX81 + RAM pack. And lost a lot of hours to the wiggle and crash! I used to put the machine on a book and hang the RAM pack off the back to maintain the connection. Good times...

> I have horrible flashbacks remembering a time when I spent a couple of hours typing in row upon row of hexadecimal (plus CRC check code for each line!) from the pages of a magazine to get a Space Invader type game on the ZX81. And then the RAM Pack crashed the machine before I could save to cassette tape - BOOM!

This. And the other horrible one. Typing in hundreds of lines of hex only to realize there was a digit you either typed wrong or was wrong in the listing, so when you ran the code it just froze.

I sense that more projects will come where similar microcontrollers will be simulating the machines from the 8-bit golden age. I wish I had the time to do it but I can’t wait for someone to do a tandy color computer/dragon32/zx spectrum/bbc/c64/etc. running on an off the shelf cheap adafruit/sparkfun/arduino board.

The super cool thing about this one is that it’s not a simulation. It’s a full reimplementation with similar functional bounds.

How about a VIC20 on an ESP32?

https://github.com/fdivitto/FabGL

There's a demo scene for the ZX80:

https://www.youtube.com/watch?v=4DFJnzSCtdg

And a pretty cool game:

https://www.youtube.com/watch?v=mw2N5k4kKxE

Here's how Kong was timed: http://www.fruitcake.plus.com/Sinclair/ZX80/FlickerFree/ZX80...

The popularity of the Raspberry Pi and Arduino makes me wonder why there wasn't more exploitation of the I/O capabilities of the simple PCs of the early days. I suppose there must have been some I/O breakout devices, but they were very niche. I guess it was a combination of cost (too expensive to dedicate a pc to a single task), and lack of cheap but useful electronics to connect to (though relays and switches could do many useful things).

There was a lot less cool sensors and peripherals. Everything was more expensive and more difficult, but people did build a lot of cool things, like hacking the Altair to play music on a radio with its RF interference.

You may want to downgrade your ideas of what the tech could do. No networking, no radio control of any kind, no real time clock, no battery backup, no WiFi, no app or web control, very limited graphics, no memory card boot, not fast enough for most applications that needed an ADC, nowhere near reliable enough to run for long periods unattended.

And expensive. The basic £49.95 kit would have cost the equivalent of £200 today. Add 16K RAM and some I/O and the price was more like £400 - which is well over what most people would spend on a box that might turn some lights on and off.

It's pretty easy to do something useful with a Pi. You'll probably end up with a mess of wires, sensors, and relays, but the core stack is fast enough to run a web server and to control useful peripherals.

Compared to a ZX81, the Pi is a supercomputer. Literally. It's equivalent to 80s era supermainframes. But super cheap. So of course you can do far, far more with it.

It was possible, just a geeky niche because folks had to do pretty much everything themselves. X10 ruled the day for remote control, and that was straight forward. Everything was costly, so there was that factor.

There was a great story in one of the computer mags of the day (Kilobaud, perhaps). Mid-80s, pre-PC. A fellow had a system (S-100 box I think) that had sensors, speech, and voice recognition. He could "Hey Siri, start a timer" type of commands.

Alas, the system was imperfect, as they all were. One day, the owner was doing something with solvents and changing clothes in the garage when the fumes set off the fire detector. Despite his pleas to cancel, the system proceeded to not just inform the fire department, but set off an alarm, and open the garage door (part of his fire escape plan) to reveal to his neighbors a shouting, half naked man, dancing in their garage.

Anyone who has seen "Electric Dreams" knows the downsides of home automation.

There were loads of addons and I/O projects. For just a taste, take a look at eg Usborne's "How to make Computer Model Controllers" from https://usborne.com/gb/books/computer-and-coding-books

(Direct link: https://drive.google.com/file/d/1FqhExLPJZHakw6RpNr_LKtmtk1h...)

Or the works of R.A.Penfold

Back in the day, the printer port was the way to interface experiments on the cheap. I had a spare printer card just in case I blew one up. There were expensive A/D boards and such used in labs, but it was too expensive for hobbyists. On the cheap, best to use a commodore 64.

It is kind of amazing that a fairly full-featured 1 GHz/512MB PC running a Unix-like OS is only $5, so you can afford to use it as an embedded microcontroller.

Microcontrollers are usually Harvard instead of Von Neumann architecture, and this one is no exception, which makes executing arbitrary code a little more difficult; the EEPROM is only rated at 100K cycles too.

Nostalgia. I built a sound card for my ZX-80 in middle school.

Very cool, thank you very much for this project. I've now ordered some PCBs as well as all needed components. Can't wait to build it!

The ZX80 screen flashed when you pressed a key. Yet they still managed to make games for it by doing cycle accurate delays to account for key processing.

indeed: http://www.fruitcake.plus.com/Sinclair/ZX80/FlickerFree/ZX80...

The ZX81 did the same in "Fast mode". "Slow mode" actually kept the screen refreshed when buttons were pushed - amazing.

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