Sinclair ZX81 (Timex 1000) Grandaddy of Computers | Nostalgia Nerd

Now, I’m not one to go on about Clive Sinclair
and his associated products….. alright, so maybe I am. But even given that, the ZX80
and it’s better selling successor, the ZX81 are tremendously important pieces of the home
micro jigsaw puzzle. Without them, we’d probably all be still stuck in the 80s, driving around
with permed hair in Audio Quatro’s, Renault 9’s and trying to work out what these fangled
Commodore things from across the pond were. Essentially, without Sinclair we’d be behind
the times as Bulgaria. So we all owe a huge debt of gratitude to
our lord commander and his fine creations… and to honour this, let’s all take a minute’s
silence. *cue loading screams* God! Every bloody time. Ironically, the ZX81 didn’t feature the iconic
loading sound when feeding bauded data from your WHSmith tape deck into the tiny door
wedge moulded computers, and the banded lines were actually a interference quirk as the
video signal was hooked up to the same ULA pin as the tape output. Still it’s a nice
effect. But back in 1980, these machines actually didn’t feature a lot of things we’d come to
associate as standard parts of the 80s micro, and other than their earliness on the scene,
the main reason for that was PRICE. These were machines designed to come under the golden
price point of 100 English Pounds. Back when Sinclair Research was a glint in
Clive’s eye whilst managing his previous company, Sinclair Electronics, Clive had dreamt of
an affordable home micro that everyone could buy into. It wasn’t until that company failed
and Clive had started up his new enterprise that this vision was made a reality. Following
on from a home computer kit, called the MK14, Clive released the ZX80. The first home computer
available in the UK for under £100, ready built (and only £79 in kit form). The machine
was based around the Zilog Z80 CPU and utilised readily available TTL chips. To keep costs
down the case was vacuum moulded and a dead feeling membrane keyboard was utilised – although
many replacement cases and even stick on keyboards sought to remedy this. The ROM lacked floating
point arithmetic and the machine’s video output was half based in software and therefore driven
by the CPU; this meant the screen would literally cut out to register key presses. Never the
less, the system sold 100,000 units and kick started the UK’s home micro scene during it’s
1980 launch. Only a year later, Sinclair, or more accurately,
chief engineer, Jim Westwood and his team had developed the technology enough to squeeze
the ZX80’s TTL chips into a semi-custom ULA package. They had also incorporated a NMI
generator which allowed the hardware to operate in slow mode and therefore stop the screen
flicker on key presses. The ROM was also expanded from 4 to 8KB by a company called Nine Tiles,
allowing floating point arithmetic, new commands and additional devices to be plugged in. Although
the new ROM, allowing decimal points did create an error in the form of the square root of
0.25 being returned as 1.3591409 rather than .5, as it should be. To top it off, Sinclair also splashed out
on a black injection moulded case, although retained the membrane keyboard. The result
of this was the Sinclair ZX81, sold at an even lower price than the ZX80 at just £49.95
in kit form and £69.95 fully assembled (this equates to about £250 in today’s money).
The dimensions of this tiny little package are just 6.6 inches by 1.6 inches high, and
it weighs just 350 grams (note I’ve mixed up both measurement systems there to keep
everyone happy). Sinclair was always very keen on design and this particular one brought
it’s designer, Rick Dickinson a design council award. The ZX81 had 1KB of base memory (the same
as the ZX80), but was expandable to 64KB using plug in RAM packs on the back – which notoriously
needed sticking on with blu-tac to prevent them falling out with the slightest jiggle
and – at worst – frying the motherboard. Graphics were provided at 24 lines x 32 characters,
or 64×48 pixels in graphics mode. These modes were output using a standard RF plug which
you could tune into your television. The output is monochrome only. The machine included Sinclair BASIC as it’s
standard language and operating system. The BASIC commands were accessible using short
cut key functions, which could be accessed using a variety of shift and function key
pressings. This saved memory as an entire basic command could be held in one ROM referenced
character rather than several if typed words were utilised. Programs are loaded into and
saved at 50 baud using the EAR and MIC sockets hooked up to a standard cassette recorder. Power is provided by a 9V DC adaptor, some
of which were recalled due to overheating on early releases. Launching on 5th March 1981, initially (as
with most Sinclair products) there were manufacture issues with the company tasked with it’s production;
Timex Corporation from it’s Dundee factory. This meant that it sometimes took up to 9
weeks to meet the mail order demand, although ZX80 owners could simply upgrade their machine
through installation of a £20 ROM chip. Even with the initial supply issues, the ZX81
was the first mass market home machine that could be bought from high street stores, with
the previous ZX80 only available through mail order. This increased access, and lower price,
coupled with the success of the ZX80 meant the ZX81 would sell over 1.5 million units
before it was discontinued in 1984. Now, back in 1981, this was a massive number and it
lined Sinclair’s pockets enough to go on and produce the Sinclair Spectrum in 1983, but
if you want to know more about that you can watch my 3 part review and then forget about
this shameless plug. With such high numbers however, came reliability issues, and stores
such as WH Smith were known for ordering a third more machines than it sold, simply so
it could provide replacements for disgruntled customers. Many of these problems were later
attributed to the problematic power supplies. Sinclair’s strategy for wooing potential buyer,
was a clever one. What we may perceive as the machine’s weaknesses today, were flaunted
as huge selling points at the time. Before even the high street availability,
Sinclair would often take out huge advertisements in popular magazines to appeal to the casual
buyer and hobbyists alike with features such as the memory saving keyboard commands marketed
as “eliminating a great deal of tiresome typing”. The machines limited ability was advertised
as being the ideal machine to ease your way into computing, with the ability to add expansions
as your knowledge grew. This was even aided by supplying the “Complete course in BASIC
programming” manual written by Steve Vickers to poise the unit as something you could just
order and then learn. The public saw these machines as a great way to understand this
emerging technology whilst jumping on the gaming bandwagon for the youngsters in the
house, and that’s exactly what Sinclair intended. Sinclair himself became a focal point, adding
a human face to the business, with Sinclair Research portrayed as a small British company
taking on the Japanese and American giants. This image was played on with “Uncle Clive”
taking interviews and featuring in adverts throughout the 80s. The main attraction however, was that low
price. The ZX81 had been designed to meet a £70 price point, as the ZX80 had been designed
to meet £100. This price was touted against machines such as the Commodore Pet and Apple
II Plus which was £630… 9 times the price of Sinclair’s Micro. The price which was based
on the experience curve technique – that a product will be more profitable selling at
twice it’s cost than three times – was the main reason the UK population was ahead of
the Micro curve compared to the rest of the world. The technical shortcomings of the micro were
obvious, but this didn’t deter people, nor did it prove to be a problem for those who
bought the technology. Remember, this was at the start of the micro scene, so many people
didn’t know what to expect anyway, and by the time they’d worked out what to do, either
it was time to upgrade, or they’d just packed the machine away in a cupboard. The 1KB base RAM was pretty limited, and offered
a challenge for would be programmers, with a full screen already consuming up to 793
bytes, system variables consuming 125 bytes, leaving only a few bytes for the actual program
and any stacks needed on top of that. This didn’t stop games like the remarkable 1K ZX
Chess being released however, which packed a working game of chess into just 672 bytes,
AI opponent included. For other games, the 16KB expansion pack came in handy and was
a very popular add on. Either way, many people cut their teeth on
Sinclair’s BASIC, and it was from this resource that we end up with so many of the ZX81’s
game pool. Let’s dive into some of my favourites; 3D Monster Maze
1K ZX Chess 3D Defender Flight Simulation Volcanic Dungeon
Cetipede Crazy Kong
The Gauntlet Amazingly Dragon’s Lair was recently converted
for the ZX81 by ex-Ocean coder Jim Bagley, squeezed in 32KB of memory and feeding from
an ZXPand SD Card adapter. It might be using new technology to feed the data, but it’s
still a humble ZX81 going the work here. AmaZZXXing. There was a sound expansion for the ZX81,
however, most software was noise free, as the base hardware even lacked an on-board
speaker. However through it’s life clever tricks came to pass including clever use of
switching between FAST and SLOW modes which which could induce tones in the video signal
and thereby creating some crude sound synthesis. It was even possible to trick the system to
display high-resolutions of up to 256×192 through mode switching. Thousands of ZX81 programs were published,
either as printed listings in magazines such as Sinclair Programs or on published cassettes
from a number of upcoming software houses and bedroom coders, and this is the exact
place we get amazing concepts like 3D Monster Maze. Psion, who would continue working with
Sinclair produced the aforementioned Flight Simulator and ICL created over 100,00 cassettes
in less than three months The machine was also marketed in the States
for just under $100, and although some were sold, it failed to perform in the same way
that it was received in the UK. However it did well enough for Timex to licence the design
as the Timex 1000 and try and sell re-branded versions..
these versions initially received huge interest, selling over 500,000 machines in five months
and gaining Sinclair over $1 million in royalties, however despite the Timex versions increased
2KB of memory, late delivery on RAM pack upgrades, left many consumers disillusioned with the
lack of software the machine had to offer. It also became evident that the US market
was more interested in pre-packaged software and games rather than education and learning
BASIC programming, and the upcoming VIC-20 solved both these concerns. Other unofficial ZX81 clones would appear
in Brazil, China and Argentina, and some even improved on the hardware. Throughout it’s life, a vast line of expansions
and printers (such as the crude but cheap “Spark” printer which used black aluminium
paper to zap text onto) came out for the ZX81, and ultimately the machine paved the way for
the incredible Sinclair Spectrum launched in 1983. The machine had a massive impact
on the UK market and it’s legacy lasts in the UK development scene which is still thriving
to this day. As for Sinclair, the companies profits rose
from £818,000 to almost £9 million after the ZX81 launch and Clive became one of the
highest profile businessmen in the UK earning him a knighthood and Young businessman of
the year in 1983. Arise Sir Clive. You deserve it.

100 thoughts on “Sinclair ZX81 (Timex 1000) Grandaddy of Computers | Nostalgia Nerd

  1. Got one for Christmas in 82 when I was little. Still have it, still works last time I checked. Learned to program on it.

  2. my first computer, or rather, gaming device. Invasion Force was my favourite. I also remember having to type games in to play 🙂

  3. I cut my teeth as a programmer at age 6 on a 1k ZX-81…today, going down memory lane is easy, as we can get flawless emulators in quantity on the internet. Today, anyone with an internet capable PC has the equivalent of a supercomputer on their desktop. And in their pocket is they have a smartphone. Astonishing progress in a short lifetime.

  4. After graduating with an Associates Degree in Electronics in 1983, the local tech giants were laying people off. It was the confidence in writing code, gained from the ZX-81, that saved my career and started a path in software development.

  5. I remember that 3d monster maze was the first game that made my jaw drop. A seemingly impossible feat of programming on the 81. But how could you omit mazogs from your game list?!?

  6. MY FIRST COMPUTER! Yep, I have fond memories of the ZX81 and its many eccentricities. The games were quite good too: I didn't play any of the ones in this video, but I remember "Avenger" by Abacus Programs, and a few that came with the ZX81 I had. However, tape loading was a bit of a problem, and I had endless issues with the wobbly 16K RAM pack, as did many others. I do remember impressing my parents with an octopus animation I made on the ZX81, however. I think they encouraged me from then on.

  7. I remember seeing this in computer magazines as a kid. I imagined that the keyboard would be difficult to use compared to my Texas Instruments 99 4A.

  8. I ordered the kit and waited… and waited… and waited. Finally it arrived, and they had sent an assembled one.I added the 16K RAM pack, printer, and modified it so I could use a real keyboard. Even in those days I could type faster than that little machine could take it.

  9. Im incredibly surprised about how clever they were in programming those games…. specially the maze and chess ones…. in a such tiny computer manage to create that is amazing…

  10. It was my first computer (35 years ago…)
    I now sell them on Ebay USA with new video composite that works with HDTV, a switching voltage regulator (no more heat) and other upgrades.
    We ship worldwide.
    I loved monster maze but it's hard to find now.

  11. Well, back then it wasn't bad at all… And it was incredible challenge for a programmer – make usefull game and… you have only fonts and 1k! 🙂

  12. Bulgaria and Hungary are AWESOME hotbeds of hacking. I wanted the kit as advertised in "Radio and Electronics" but dad made me wait for the complete machine as he had so little faith in my soldering skills 😦

  13. I had the official 16K expansion, which I kept in place with a rubber band that went all the way around the computer. It was $100 US assembled and $50 for the 16K. I bought it before the TI version was released.

    I learned assembly language on it by converting the assembly language into numbers by hand, then putting them into a string with a basic program.

    While the mnemonics are different, Z80 assembly language is pretty much the same as 6502, so it the move to the Atari 8 bit wasn't difficult.

  14. I still have mine and the tapes/ memory pack.Me and my brother used to spend hours typing programs in,then my mum would move the power cable and all the data gone in a flash, Happy days, loved the 80s

  15. Sinclair stuff was the Austin Maestro of the tech world – shockingly bad. I have one of his early calculators and compared to my brothers Casio, had awful keys, a rubbish display and ate batteries. The build quality was junk as well. Not that it particularly mattered but the scientific version someone had at school was a lot, lot slower as well.
    I suppose his products were cheap but then so is a bag of dog shite.

  16. Sinclair stuff was the Austin Maestro of the tech world – shockingly bad. I have one of his early calculators and compared to my brothers Casio, had awful keys, a rubbish display and ate batteries. The build quality was junk as well. Not that it particularly mattered but the scientific version someone had at school was a lot, lot slower as well.
    I suppose his products were cheap but then so is a bag of dog shite.

  17. My uncle gave me his ZX81 back in 82 (I was 11), it's in the garage and still works, though the keyboard membrane has several chewing gum foil wrappers acting as contacts.

    I remember being more interested in seeing how the basic code worked than I was in actualy playing games. As with the ZX-Spectrum later on, that keyboard and it's multi-keyword/key meant one could type code blisteringly fast once memorized and memorize it I did. Those were the days of taking days off of school as my dad read line after line of code out of countless magazines and books. The golden age of computing for sure, when computers still had soul 🙂

  18. Storing commands as single-byte tokens was/is business as usual for all BASIC interpreters, Sinclair computers just did the least to hide it. Single-key commands may just have been as much about saving the user from typing repeating keywords (on a pretty horrible keyboard) as it was a cost-saving method.

  19. – Just had a bell ring in my head – please could someone tell me what that is on the screen? many thanks in advance.

  20. ZX Spectrum released in 1983? I think you're out by a year there!

    And it's Mic pronounced Mike, not Mick. Since it's short for Microphone.

  21. I used to own the ZX81with the memory extension. It was okay – but the membrane keyboard did not last long. Storing programs & retrieving programmes off cassette audio tapes was cool – but slow and pain in da butt. LoL

  22. Ahhhh. The ZX81. My first computer. I fondly remember playing the game Mazogs on it. I also remember spending about 3 hours typing out a program, to only find that it won't run and it wouldn't tell me why. Unfortunately, any further programming or gaming on it was quickly halted, after using it during a thunderstorm, right royally screwed it up 🙁

  23. 1k chess is great but there's a better chess game for the ZX81 nowadays called super micro chess. It has all the rules among other improvements and still runs under 1k.

  24. This was my first computer. I was so clueless that I thought when you "read in" a program from tape, that meant the program moved from the tape into the computer, then you would have to write it back out when you were done or it would be gone. I've learned a thing or two since then.

  25. I dunno. It's cool there's a video about ZX81. This computer rulez big time. Thx for including it to the show. But… Really? Really this Bulgaria was necessary? I mean – so many great progs for Sinclair came from the East (and still comin', for that matter). It doesn't seem right.
    Sorry if I'm too serious.

  26. I got one of these, seems like about 81. I remember it was a big deal because it was only $100. Back then there were computer magazines with code articles that you could type in if you wanted to experience what the author was talking about. There was one that said if you would type in this page of code on the sinclair you would see the skyline of Richmond Virginia. Since I lived there, I did it and lo and behold it was just like the area of town I was in… I remember being blown away by this. It was of course terrible resolution in 2D grey scale but very impressive.

    As been mentioned by other people it was really just for playing games and viewing graphics as far as I was concerned. My screen collapsed completely upon each key stroke. It would only be for a .5 second but that got old. When the Commodore 64 came out mine was history. About 10 years later I was at a Dr. office in Boston and I noticed the doc has one in his examining rooms. I asked him what he was doing with these old Sinclairs and he said the printer (can't remember if the printer was a Sinclair product or something else, small thing about 1/2 the size of the zx81) He said he was using Sinclairs zx81's with the attached printer to write out scripts for the patients??? Something about the printer paper was the same size the druggist used. Anyone else remember this? a little fuzzy.

  27. Someone might have mentioned it in an earlier post, but I'm not going to read through all 219. The ZX Spectrum came out in 1982. I know this for a fact as I had one then (for about 12 days before it died).

  28. I'm late to the party, but just checked out ebay to see what the collectability value is on these, and they're still selling complete setups (printer, computer, etc) for an average of $100. Sure there isn't much one can do with one other than show the unit off to friends, but it isn't that expensive either.

  29. Memopak RAM packs came with a strip of velcro to stick between the ZX81 and the the RAM pack to help stop it wobbling. You didn't need to use blu-tak. My 16K Memopak was very reliable – much better than the official Sinclair RAM pack which had a tendency to cut out and lose the program. Memopaks also fitted the ZX81 case profile much better than the blocky Sinclair one.

  30. Sigh. I can still remember recieving a birthday invitation printed on a spark printer…way back in 1982…good memories

  31. This computer is why I became an engineer and left poverty. I wrote a program on this for my dad's finances and they made at most $10k a year in 1983. The program was to figure out his business losses for taxes.

  32. Don't you just love watching some random channel and suddenly the guy drops a purely hateful unrelated comment about a country? Someone get that loser a Snickers, he got issues. If you're a girl let him touch your boob before he strangles his cat cuz thats how tragedies happen with those incels.

  33. I has a Commodore Pet in 1978 so Commodore computers where everywhere before the 1980 release of the ZX series. I used a ZX 81 and put cold milk cartons on the memory expansion to keep it cool.

  34. The 4k Pet was never sold in the UK we got the 8K and in 1978 I paid £695 and I had to sell my car to pay for it. If I remember the TIMEX versions of Sinclair computers where not 100% compatible with the UK versions.

  35. Since a heck of a lot of ZX81's were sold as kits, it is a shame they did not include an option for AV-3-1910 sound chip and 16K Ram on the motherboard, or for assembled machines, a socket a sound chip and extra Ram. The sad part is there is enough room on the motherboard to add these and it would not have cost anymore.

  36. 6:05 I find it hilarious that the computer on the desk there, at the company manufacturing for SINCLAIR, is an AMSTRAD by the look of things.

  37. Someone I knew gave me his old American versions of the ZX81, the Timex Sinclair 1000 in the late 80s. It include the 16k ROM expansion pack and the Zx printer, a spark printer. Played around with it for a short while. I found the membrane keyboard to be pretty poor for extended use though like the ease of typing basic commands with key combos. The TS-1000 sold for about $100 in the U.S. back when it debuted. Interesting footnote in computing history, though like netbooks being displaced by iPads and other tablets, the ZX81/TS1000 where just not quit up to the task compared to the ZX Spectrum, Vic20, or even Atari. Sometimes it's better to spend a few bucks/quid more to get something more usable then to just go for the cheapest.

  38. when people talk about the ram packs they only mention the sinclair ones, but the 3rd party versions were twice the size for about the same money(datel electronics, romantic robot and kempston which had a joystick port on it, i had a sinclair one but also had a datel 96k one though never found anything software wise to use that much memory lol, another thing was they are stackable if you have the type with the pass through slot on the back, you can put another pack on the back and have 32k.

  39. Graphics? We didn't need no stinkin graphics! We had imagination back then. And patience. It was amazing what clever programmers were able to do with so little to work with. I eventually moved up, but I had a lot of fun with the TS1000 before that. (Timex 1000> Vic-20> C=64.)

  40. Just watched you pull out your ZX81 from its nice slide out box with a tear in my eye and remembering when I was robbed and the room trashed. My ZX81 survived having been thrown across the room but the box had been ripped up and the Styrofoam broken. Sad times but at least the micro lives on to this day.

  41. I had a Timex 1000 with 16k pack. Bought a couple of accessories mail order: a stick on keyboard (which was A HUGE improvement) and a bracket that stopped all memory pack crashes. I played the shit out of frogger and a couple other games I typed in from magazines.

    My dad who had been a COBOL programmer for over a decade when he bought it for me, wanted to make sure I wrote my own software as much as possible so he wouldn't buy too many tapes for me.

  42. The ZX81 manual was miles ahead of other manuals at the time (or even now). I've shown it to a number of modern school kids while talking about early computers and one thing that comes across is that it is clearly aimed at someone who has never even seen a computer before.

  43. The Sinclair ZX81 was my first ever computer and also gave me the skills I have today as a programmer, I started as one of the backroom programmers 😀 … now 36 years on I am a professional software developer and it all started with just 1K and a dangerous heat plate that burnt my leg and melted the bottom of the ZX81 case! !!

  44. I had one. I mainly recall severe anxiety due to the crappy power cord connection. I wrote millions of lines of code, and that damn computer was just like Lucy holding the football for Charlie Brown, every time I got close to being able to save it to the cassette it would go POOF.
    Good times in retrospect.

  45. …was there ever a kit to make a ZX81 into a portable?

    I feel like it's small enough and low-power enough even with '80s batteries it could have a decent run time

  46. My first home computer, 99 Dutch guilders at Vroom&Dreesman warehouse it was a risky decision to buy it from my household money, but my whole family helped when coding in hexadecimal machine language. First try was a shock because all lights went off, not only in my house but in the whole neighborhood!

  47. I never liked to program on ZX machines or didnt really use them that much (still they are a big part of the 8-bit era and well deserved). I think the price was too high in my country so it was probably a big deterrant. Instead the best machine – that i loved in the 8-bit era was the Spectravideo 328. I loved the keyboard and the BASIC from microsoft. Less peek and poke…and function keys that you could program…and the sprite handling…in basic commands(!). Dang good memories so much fun doing different programs. I was 12 years old or so. I read every book about computers and about BASIC language i could find…and was dissapointed when the library didnt update with new books. I remember this – was pretty upset lol.

  48. I purchased the ZX-80 as my first computer and it wasn't the best in the world, but it worked for me and I was able to use Basic which was on it along with MS-Dos for that machine which was different than the other versions.

  49. That was my first computer when I was a kid. Fortunately I managed to persuade my parents to return it and buy me a Commodore. IT WAS AWFUL

  50. I'll have you know that around the same time Bulgaria was mass producing Apple and IBM clones in sufficient quantities to not only stuff classrooms in most bigger schools, but also for export.

    Being this backwards has sweet fuck-all to do with lack of access to inferior hardware.

  51. That was fascinating, and brilliantly done. I recall I actually sold my Atari VCS to get one, as I was so intrigued by the idea of this little computer you could programme. Even though I loved the Atari, and it was somewhat a backward step for gaming, I was hooked on the whole idea of home computers..

  52. Like many others I started programming on the ZX81 and went on to be a lead programmer at EA many years later. What a great machine.

  53. My very first computer. I added an external keyboard, a 16K memory pack and a tape recorder. Games on cassette would take around 7-8 minutes to load. There was a remarkable flight simulator which worked on the 64×48 pixel display. I don't know if you came across this, but it was announced that some UK government departments were supplied with ZX81s because, for certain duties, they worked faster than PCs of the time.

  54. The Raspberry Pi Zero of their age … Many people can thank Sinclair for teaching them computing, even if later they upgraded to Atari or C64

  55. My grandpa worked at IBM Boulder, and he had one of these. My dad said it was a piece of shit that with no memory

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