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Forum Index : Microcontroller and PC projects : 1K was more than enough back in the day...
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Nimue Guru  Joined: 06/08/2020 Location: United KingdomPosts: 367 |
Off topic a little: Away from discussion over EduMites, I am digitizing and up scaling the artwork from Sinclair User. This article in the 4th edition (1982) caught my eye about a teacher writing educational material on the 1k ZX81. SinclairUser_67.pdf Some much, yet so little has changed. For what its worth -- this is what I am digitizing/upscaling -- the work of the brilliant graphic artist William "Bill" Scolding --- the plan is to digitize all his artwork and bring it together in some manner.  Happy memories of Sinclair User. N Entropy is not what it used to be |
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| circuit Senior Member  Joined: 10/01/2016 Location: United KingdomPosts: 245 |
I do hope and trust that you have sorted out the copyright permissions necessary for such a project... |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6814 |
1K? You were lucky! We 'ad a foot of paper tape each and we 'ad to make holes in it wi' us teeth while sittin' in a basement wi' 4 inches of water in it from a leaking pipe! (No Yorkshire men were harmed during the making of this post.) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 4047 |
Paper! Basement! Pipes! Thee were reet posh Mick. Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Back in the 80's, I had both an Atari 800XL and a Sinclair ZX81. The 1K in the ZX81 was practically useless, and IMHO crippled the ZX81 from doing pretty much ANYTHING useful at all. It was a toy, not a home computer.  It does not take much BASIC code, to fill up 1K of RAM.  Having said that, I know it had it's fans, but to me, my nickname for it was "The wedge", and was most useful when paired up with a door to hold it open. I also had the 16K RAM cartridge thing, but it used a horribly unreliable edge-connector, and if you simply BREATHED near it when it was running, the connections to the RAM would be interrupted and the entire computer would crash.  BUT - it was the cheapest home-computer you could buy new at the time, and they sold like hot-cakes, despite not REALLY being of much use at all. ....and don't get me started on the SAVE/LOAD via domestic audio cassette tape idea. But then - everyone's a critic.  The movie MICROMEN is very well done, and documents this whole period back in the 80's rather well, and anyone into MCU's or computers should watch that movie. Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
somewhere i have a ZX81 that has had the 1k RAM chip removed, to be replaced with a pair of 2k 6116 RAMs mounted on a bit of veroboard. this (4k) made the ZX81 far more 'roomy' (or should that be 'raamy'?). today, the same can be done with an 8k or bigger RAM chip. as i recall, 3.75k was the point at which the screen buffer became permanently allocated at full size. i think that in the context of the time the ZX81 was a major step up for school kids who might have had a single computer at school with a card reader. for a moderate sum of cash one could 'tinker' with programs that were a few dozen lines long. pitiful by today's standards, but a pretty major thing back then. you could learn about algorithms, process flow, variables - all the building blocks of an industry that was about to open up to the masses. cheers, rob :-) Edited 2023-03-23 10:38 by robert.rozee |
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| gadgetjack Senior Member Joined: 15/07/2016 Location: United StatesPosts: 146 |
The ZX81 was the first machine I owned that worked with out a terminal/keyboard connected to it. I was in heaven (for a short while). More power , more ram , better video , color , yes , I was hooked. Still have fond memories of that computer , but there's no going back. |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6102 |
I had a 16k plug-in ram module. Eye watering price! The connector was not it's best feature and regularly caused grief. Jim VK7JH MMedit MMBasic Help |
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Hawk Senior Member Joined: 15/07/2021 Location: AustraliaPosts: 141 |
I have also been digitising some old artwork. Recognise this? .png) On the topic of ZX81...I ended up buying a second hand one to drive my final year uni project, as I needed a Centronics parallel port, and my Atari 400 didn't have one. I can also attest to the flakiness of the 16K expension. Hawk |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
It's a shame that they did not sell the ZX81 with even 2k of RAM(a ZX82?) - would have been better then the extremely lean 1K. But then, back then, RAM was relatively expensive, and we know Clive... But yeah, I was and still am not really any fan of that thing, but I will give it it's due - it was cheaper then any of the alternatives, and still hooked up to a TV in the same way as home computers costing three times as much cash at the time, and still managed to squeeze in a BASIC interpreter - pretty clever, really, and brilliant marketing making it so affordable, it was just let down by so little RAM left to play with, the unreliability of the 16K RAM-pack, and the horrible audio recorder idea for saving/loading programs. But then, costs had to be kept to a minimum - I understand and appreciate that as a small business owner myself.  The audio cassette recorder concept would have been brilliant, if it had worked, but so often it did not. Perhaps it worked much better with a proper HiFi cassette deck that would have had much better performance over a cheaper portable cassette recorder. If someone reading this ever did that with the ZX81, I would be interested to know if that made saving/loading programs more reliable.One thing I DO remember liking about ZX BASIC, was the keyword shortcuts on the membrane keypad thing, where one keypress would "Type" the whole keyword for you - that was clever, cute and very much unique to the ZX81.  Smoke makes things work. When the smoke gets out, it stops! |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2141 |
" The audio cassette recorder concept would have been brilliant, if it had worked, but so often it did not. " Maybe the problem was the encoding method. You need one that can cope with speed fluctuations. The MicroBee worked fairly well with quite cheap cassette recorders. |
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IanRogers Senior Member Joined: 09/12/2022 Location: United KingdomPosts: 151 |
I used C30 tapes as C90's did stretch. But I remember that someone made a 'fast loader' cranking the baud up to.. well much faster than the 1200 Clive used.. It seemed to be 'as' reliable. Who knows. Unlike Grogster, I loved these units and I still have most models. I now use the pico with the zx emulator which is pretty damn good.. Edited 2023-03-23 17:57 by IanRogers I'd give my left arm to be ambidextrous |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6814 |
True, the ZX didn't have much RAM, but it was used very efficiently. The only ASCII stored was what the user entered or as REM statements. All keywords were tokenized and there was no full ASCII editor as such, it tokenized and de-tokenized on the fly. It was surprising how big the programs could be if properly written. Certainly big enough for most school kids to enter without losing patience entirely, and that was the target audience. Sinclair's idea was to make computing affordable for kids, especially for those without rich parents. Obviously that meant that the machines had to have a pretty low spec, but by using some clever design a lot was achieved using a low number of components. The concept of combining the ZX80's logic into a single ULA on the ZX81 was very neat and solved a lot of problems by taking the screen refresh load off the Z80. Even cleverer was preventing the Z80 from writing to the screen while it was being refreshed simply by stopping the clock on the Z80. :) The Sinclair BASIC was generally very good. It had its foibles, but the string slicing system was so brilliant that I honestly don't know why other BASICs haven't copied it. The cassette system worked very reliably with the right recorder and very unreliably with the wrong one! Tape systems have always been a bit like this as domestic tape itself is a poor medium (stretching, print-through etc.). Unfortunately there was simply no other option at the time. We went through all this in the 70's with the Nascom machines and, believe me, the ZX81 cassette system wasn't too bad in comparison. "Soundhog" cassettes? Just say "NEVER!". I won't knock the ZX80 and ZX81. They were responsible for gaining the initial interest of thousands of IT professionals. They were crude machines by today's standards but were built right down to the minimum price. Unfortunately that led to reliability issues with the ZX80 (which was also expensive to build). Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1115 |
well the 1 KB ZX 81 was my first Computer and The manual has introduced you step by step to the Basic programming language 'no comment |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6814 |
By the time the ZX81 came out I'd already been into home computing for a while, but I still bought one. :) It's difficult to get the perspective now, but in the early 80's we were only just starting to get anything that resembled a "home computer" in the UK. The US ha had it's boxes around for some time, but they were seriously expensive over here. I got a Tandy Model I Level II with expansion interface and two floppy drives, so I know! Up until that point the Nascom 1 didn't have BASIC at all. That only appeared on the more expensive Nascom 2. Both were for electronics fans and neither looked good in the living room. :) The ZX80 and 81 were the first UK machines to boot into BASIC so they were the most accessible. I'll be honest, I loved the Spectrum. I feel that it suffered because of the gaming element because it was actually a very good general purpose machine. To get colour, of any sort, at that price at that time was amazing, as anyone who has come across the Pluto colour graphic boards for the Nascom and Gemini computers will assure you. It made a remarkably good, cheap Videotex/Viewdata terminal. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
...perhaps I am being too hard on the old thing... Smoke makes things work. When the smoke gets out, it stops! |
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| Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1115 |
of course, I bought the 16K memory expansion after less than a month. The 1KB were sufficient to get to know the Computer, but quickly too little to "work" with it. The Spectrum was then just the logical consequence. 'no comment |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4256 |
The ZX81 was sold as the Timex1000 in USA featuring 2k of memory (and the box said: only 4 chips). The ZX81 board layout was prepared for either - 2x 2114 (1kx4) RAM chips -> 5 chips in total - 1x 6116 (2kx8) RAM chip -> 4 chips in total (ULA/Z80/6116/ROM) A pretty common change in netherlands was to remove the 2114 chips and put a 6116 in the ZX81. Volhout B.t.w. The code name for the spectrum was ZX82 as I recall Edited 2023-03-23 21:20 by Volhout PicomiteVGA PETSCII ROBOTS |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
now if we could just shoehorn a pico running MMbasic (VGA) into a ZX81 case... and the box could say "only 2 chips"! cheers, rob :-) Edited 2023-03-23 23:52 by robert.rozee |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6814 |
That should be easy enough. There's loads of space. :) Interfacing the keyboard is the difficult bit. Anyone got a Speccy to PS2 adapter? I'm not sure that I fancy typing out keywords in full on the ZX81 keyboard though! Don't give me ideas... I have two or three ZX81s in the shed. I bet at least one of them doesn't work... Edited 2023-03-24 00:03 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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