ZX81 Adventures! 

This was the machine I learned BASIC on in the summer 1981. By the time I went back to school, I was quite proficient in programming. I'd spend any spare time in class writing programs for all manner of things. That machine meant everything to me, back then. Despite having fond memories of it, I don't think I'd last more than about 5 minutes on one, now, before getting a bit bored. Still, it was over 40 years ago.

I was 10 and saw a ZX80 at a School Fayre and that was my jaw drop moment in life. It was totally mind blowing at the time. Yeah, things have moved on more than ever imagined but that first experience with a computer won't be forgotten.

I was only 4 when my household was blessed by a ZX81 suddenly appearing. The start of lifelong love affair with the microcomputer, and instrumental in me later becoming a software eng. Its such a special era we were all lucky to be part of

i am simple man - I see ZX81 in Thumbnail, I watch'n'like 🙂

I spent hours entering hex from a magazine into one of these, back in the day. We've come such a long way since!

My uncle was an EE, he had 10 year old me doing all kinds of crazy things to my coveted ZX81. We made a printer interface, a video inverter, we decoded more of the memory map, I had extra ram, a second switchable ASM Monitor rom, and of course I had the whole thing situated in an old teletype keyboard that weighted about 30kg, and where I had individually rewired every single reed switched key. Took weeks and weeks to do that. Much to his disappointment I became a software guy, though I did keep it at the low level asm programming end of the scale for many years. Good times.

Beautiful machine, people call it names now but in the 1980s this was much loved and respected, you got used to the limitations of micro computers in those days

My 81 got me started, worked IT/comms most of my working life. My brother and I saved up our money and bought one of these little things, probably had the biggest influence on my life. Amazing what you could do in 1K.

Ah, my very first real computer. I remember the thrill of first getting it, as well as the nightmare's of working with it. I actually still have it. I the ZX81 it for almost a year before moving off to a VIC-20. A completely different world. Still I respect the ZX81 for introducing me to computers.

Use to play on a ZX81 and put in the lines to play a game and no tape yet, so after a failure type in all again. You have fun and that is important!

I got the ZX81 as a kid around 1982 with that monster maze game that I loved. I bought a gaming magazine with a program that you could code in which took me all day. I was so proud to show my sister's friend the game that took me so long to make, then she tripped up on the adapter cable and pulled it out.

Thanks for a great trip down memory lane and great project fun!

Had the ZX81, 16K Ram Pack, Thermal Printer, and manual. Got the train to drive across the screen and printed the menu's for my Grandads Hotel, which was a BIG hit with the guests. Learned BASIC, went on to code a supermarket stock system for cash for PC's. Bought my first motorcycle cash. :) Happy Days

I had one with all full hardware add on’s including Hi rez . I used for porting a full Startrek game in Basic from our CDC Dec10 system in college. I was able to get the entire game in HiRez running exactly as it ran on the full Dec10. Took me months, but was very rewarding to see how powerful this little machine was and could be.

10 PRINT "ZX81 RULZ" 20 GOTO 10 RUN

So cool. One of these was my first computer. Thanks for bringing back memories.

I sold my Atari Video Game system to fund my purchase of a ZX81 back in 1981. I couldn’t afford the built version, so I got the kit for £49.99, which was a lot of money for a 16 year old still at school back then. My dad built it for me as he was a dab hand at electronics. I loved the wobbly RAM pack and found blu-tac held it on. The following year I sold it and out the money towards a BBC Model A. I had never seen that computer as they hadn’t been released but had an A4 spec issued by Acorn outlining it, and it looked good so put in an order. When it arrived it was all new and modern with sound and colour! The machine I received was serial number 000137! I eventually purchased all the components and upgraded it to model B spec.

Hi my college lecturer said the best it can do is when it's filled with cement and use as a doorstop. I loved it LOL

ZX81... started me on my journey to becoming an Electronics Design Engineer. I used the good old Z80 and its derivatives for many years befor eretiring.

Bravo! I still have my ZX81 unused for 40 years and still in its box. When I find a tv I’ll see if it still works - you’ve got me interested again..

The TS1000 was my very first computer. $99 well spent. Thanks for the blast-from-the-past!

Loved it. I had the Timex Sinclair 1000 as my first computer. It was amazing!

Thanks. You just took me back 40 years. Was it really that long ago. I appear not to be alone in all those ZX81 owners who have kept theirs. Amazing that you can stil get spares.

I was finishing my undergraduate degree in chemistry and going on to my PhD in the same field when ads for the ZX81 started appearing in Scientific American. The verdict was that our TI and HP calculators could do 90% of what this ZX could do, but complicated things like realistic numerical integration were possible only on the Sinclair. I still remember sitting in my office pressing those membrane keys entering in the formulae for Gaussian quadrature.

It was bloody brilliant!!!! It paved the way to allow kids back in the 80's (me) to access computers. I remember on xmas day typing in the "Plough" program for the manual and saving it on a cassette..

ZX81 - VZ200 - VIC 20 - AMIGA 500 - Into the world of PC. That's my home computer adventure.

True deep dive into computer history. Amazing!

I bought my first ZX81 in kit form in late 1981. The bug bit me again recently so I now have 3, 2 of which will be sold on with internal 16KB and composite video mods. The one I'm keeping also has a stripped-down AV2HDMI converter built in with an HDMI port on the right hand side. Being able to plug a 1981 black-and-white computer in to a 2021 55" OLED TV and still get an excellent picture is both satisfying and strangely amusing! 😀

In 1983-84 I bought one Timex Sinclair 1000 which had only 1 kb RAM but you could buy a 16 mb memory card extension. Most of the Spectrum's software ran in the little TS1000..It was such a little wonder,... Thanks for sharing your video, it broght me back to school days and basic programming...

I'm always impressed by the hardware hacks that the designers used to make the ZX81 so simple (and cheap). Particularly the way they abused the Z80 to generate the video display, and the fact that the cassette output is the same thing as the video output. I also seem to recall that the keyboard is somehow directly connected to the address bus. Then there's the clever "compressed display file" idea to allow a 1K machine to have enough RAM left over to do something useful.

I started out with the ZX-80 with the whopping 1K ram, but the incessant flickering screen refresh gave me splitting head-aches. So eventually I ended up with a ZX-81 with a 64K of RAM, a dual serial interface, a 300Mb harddisk (size: small fridge), two 8" floppies, a Mannesmann-Tally 300lpm drum greenbar printer, a jerry-rigged joystick and a rewired VT100 Keyboard. It ran CP/M-80 and I've actually done some (for its day) decent COBOL programming on it. If I fired it up with all the bells and whistles attached it made the lights in the whole building dim for a second or two (I suspect because of the diskdrive) and people would wonder when I would achieve lift-off with the infernal contraption with all of the racket at start-up. After that room-temperature would rise at an astonishing pace but since I like it toasty anyway, that was not an issue. Ahhh, those were the days!

Thanks for showing the ZX81 on your channel! I'm in the US and my first computer was a ZX81 (not TS1000). It shipped from Sinclair Research in Nashua, NH. I lived in the south back then but now I drive through Nashua to get to school from Boston a few times a week. I should actually try and find their old offices. Instead of replacing the membrane, I cut it as close to the keyboard as possible and moved the two connectors there, gluing them to the case, and used a normal ribbon cable to bridge it to the motherboard. It saves the original keyboard and should last indefinitely since you no longer bend the membrane connectors, causing cracks. I'll be doing an internal 16K upgrade this summer, hopefully, though I just have an IC, not a circuit board like you do...so I'll have to figure out what it needs. Also, I recommend OTLA fast loader software, which converts the wave file (or .p file) to fast loading wave files and you can load Monster Maze in seconds. I use it all the time from my PC to ZX81 and it works perfectly. If you don't like the token keyword-type programming the ZX81 forces on you, I wrote a ROM Emulator called ZXSimulator where you can type each command (perfect for touch typists)...you can find a web version online. Btw, for that first composite-mod board, could you turn the board upside down? Cheers!

Living in Australia I never had a thing for Sinclair’s, but this presentation was quite interesting and I enjoyed watching the Mods. As Mr.Lurch always says “I did a lot of swearing”.

There was a really hard 3D Defender on the for the 16k ZX81. It was by the ubiquitous J. K. Greye Ltd. It pushes the limits of the machine, but it's fun. There are a few videos of people playing it, and it's aged quite well.

I've still got mine, and my Spectrum, and my QL. 3D Monster Maze was amazing at the time. I was working at ICL as a student in 1983, working on Perq computers, and the 3D maze on those was amazing.

Not sure why, but it always makes me smile to see Sinclair computers getting used outside of the UK. Lovely clear picture on the ZX81 after your mod. Top work!

Hi, when I got my first ZX81 at the age of 18. Mum said "That cost £35.00". Well it was 41 years ago. And my reply was "Yes its a computer for £35.00. Can you believe it?" And down the years I got a 16k expansion pack for it and a printer (You used special paper for the ptinter that was two pices of paper and a layer of ink dust in the middle of the paper. Now the top paper was so thin it could be burnt away. With the print head as the printer was not printing anything as the print head removing the top layer of paper reveling the ink dust in the middle and melting it. To make it look like it was printed.) I had fun with my ZX81. Playing all them silent B&W blocky games. Also I used a cassette player as the storage media. Because that is all we had at the time that would record and play back sound.

Was my introduction to computing, fond memories :)

We got a ZX81 when it was first released in the UK. We had a 16k ram pack with it. Without fail, you'd get to the end of typing in a game from a magazine and you'd accidentally move the ZX81 and the Ram Pack would disconnect and you'd loose everything. We loved it though.

My first conputer, bought second hand, used for one day, keyboard stopped working, previous owner took it back. I bought an acorn atom the next day 😂 Nostalgia galore Friend had one and lost a lot of typing due to the ram extension not being enough of a secure fit

The first computer type graphics was a since curve drawn by this at school in 1981, jaw dropping at the time. I used to love typing in the progs from magazines for it and the speccy.

I have one of these! Although called a Timex Sinclair over here, I had the 16k ram pack that slid in the back with a rather weak conection that would eventually break. It was the first "PC" I got that was my very own. Still have Frogger and Visicalc on cassette rattling around in the junk drawer.

I remember saving for one in the 1970s. Typing basic for hours to get a syntax error. Happy days.

You partly scratched my itch, but I still gotta have one LOL

Good God! My nightmare returns!!!! I've had both this and the TS1000 with the RAM pack. Thank God for the TRS80.......

My father bought it as a kit in the Uk and built it. I used it quite a lot. Never went past 1 kilobyte memory but I learned about Basic.

Wow, this takes me back. :)

Just wanted to say hello I live in Australia and when I was in the UK I love spectrum 48K and still miss it so I'm loving your videos

Great video Mr.Lurch! The ZX81 (and the ZX80 before it) was on the list with which I annoyed my parents back in the day. I've been into electronics for as long as I can remember, saving pocket money to buy electronics magazines when other kids were playing junior cricket. I can remember seeing the Sinclair machines in the UK magazines and I wanted a home computer so badly! My parents finally relented a few years later and I ended up with a Commodore 64 (I still have my original!)... but in later years I still wanted an early Z80 machine 🙂

The great small tool for beginners. I admit I filled in two hours the memory of the ZX81 my brother gave me with lines in Basic and an array on the screen. I bought my first Atari ST a week later.

I actually remember picking up a ZX81 at a rummage sale when I was in college and playing around with it a little bit... still remember briefly powering it up with a 9V battery because it didn't come with the wall wart. Didn't keep it long as I had my trusty C64 waiting for me at home.

Thank you. While studying, I had the QL which was cheap after Sinclair got bankrupt. Psion Software, with spreadsheet, text processing etc. And the microdrives.

RAM pack wobble, nothing that a little blue tack could handle 😂 Lovely vid, took me right back 😎👍

One of my more unpleasant memories in using the ZX81. Spending hours (days) typing in basic code for an adventure program or star trek text game on that membrane keyboard. Only for the power adaptor to slip out of the wall socket, or someone turn on a washing machine or iron nearby causing a power glitch. Or even if I looked at or breathed on the computer in a fashion it didn't like. To have it lock up, or completely reset loosing all work done. Thanks to the ZX81, I learned to advantages of saving often early on. Of course waiting 5-15 minutes to save (when it did save properly), as well as being able to locate a previously saved program on a tape with multiple saves was not fun either. (That Tape Counter was not always accurate.)

I had a new Timex/Sinclair TS1000 with 16K Ram Pack. I did a number of Mods including larger heatsink, a setup to use a Polaroid Portapulse battery from a Polaroid Instant Camera Film Pack for portable power. My senior year of HS I designed and made a Printed Circuit Board for Magnetic Reed Switch Keyswitches with clear cap covers. I sized and printed the TS1000 Keyboard layout creating a graphic for each key. the custom keyboard was external and used a ribbon cable.

"Ram-Pack Wobble" I'd forgotten about that lol

Found out that cleaning the edge connector and ram pack connections with alcohol makes a huge difference to crashing from ram pack wobble. After 44 years old this stuff is going to be dirty and oxiidized to hell especially since they never used proper plated pads for the edge connectors. I have the one with the infamous square root bug and rubber chicklet keys.

Bought mine when I was a kid when they just came out. I also bought the optional 1k ram pack that slotted in the back I think.

ZX81, my first computer. The empty shell now hangs on the wall like the work of art it is

In the USA as a kid, I got the Timex Sinclair 1000 version. It cost me $20 brand new (on clearance I think in about 84-85.) Also got the 16k RAM for $20. I had a VIC-20 and a Colecovision at the time, but still had lots of fun with this little machine. My nostalga for it came too late, the price just isn't worth it to me to get another one. Enjoyed the video. (P.S. I am from the USA, but have lived in AUS for 20 years. enjoy your vids.)

My first computer, a lovely little machine and so cheap too! Apparently back in the day you could get non-Sinclair RAMPacks that take you all the way up to 64 K of memory! The game that blew us away as kids was Rocket Man, a game with PROPER graphics! Lovely vid, sir!

OMG, memories... The ZX 81 was my first computer. Before I bought it I read a BASIC-book from the local library. When I understood this programming language, I was ready to spend my money. I still remember programming a slot machine with it, when after several hours deep in the night I accidently pushed the 16k memory upgrade with my hand and all the progress was gone... And yes, as soon as I had earned enought money, it was replaced by the Spectrum.

Que recuerdos! Mi primera computadora por allá por 1985. Tenia 14 años cuando ese modelo llegó a mis manos, y era un modelo de segunda mano. Cuando se estropeó el teclado (por el uso), tuve que hacer un teclado de cartón (no vendían un teclado de repuesto), donde cada "tecla" hacía contacto entre dos líneas de láminas de cobre, las que se cruzaban formando una matriz de líneas de conexión soldadas a los cables que luego se conectaban a las dos entradas del circuito central, tal como lo muestras en el vídeo. El teclado formaba filas y columnas, y la tecla seleccionaba una instrucción por medio del contacto de un punto en esa matriz. Ese teclado de cartón resultó ser más rápido que el teclado original, y resultó fácil de reparar. Lo usé hasta que conocí en la escuela el Timex Sinclair 2048, y luego el Atari 800 XL de un vecino y amigo. De ahí me pasé a un IBM PC "Mytac" cuando entré a estudiar programación, y de ahí el romance se acabó cuando pasé a formar las filas de programadores aburridos. Amaba esa simplicidad que ofrecía el ZX-81!!! Tu vídeo me transportó a mi infancia, cuando se olía en el ambiente esa sensación ochentera cargada de ansiedad y esperanza por un futuro tecnológico lleno de aventuras tipo "Tron".

When they started importing these into the US they sold them from their warehouse in New Hampshire, my uncle traveled up that way a lot so this was my first computer. I quickly got tired of the keyboard, since they also sold the kits and parts at the warehouse my uncle picked up a few spare keyboards and he also got me a keyboard out of an old VT terminal being tossed where he worked. Used one of the spare keyboards to figure out the schematic, wired up a bunch of keys and connected them into the ZX81, and cut out the "keys" and glued them in place on my home made keyboard. Being able to type normally was a huge improvement, and no worries about bouncing the 16K pack.

I just recently did the simple composite mod on my ancient Timex Sinclair 1000. The keyboard was dead, because the cable was dried out. Rather than replace the keyboard, I created my own PS/2 keyboard interface and port on the side. Now I have a full-sized keyboard with working backspace and arrow keys, using the original membrane keyboard for reference. Next I want to try to redirect the LPRINT command to a serial connection.

This was the best $99 PC investment ever made. I got all the way up to the 64 K plug-in memory module, and still have some of my program cassettes. As a nonprogrammer, I learned more about programming with this thing than anything else that I had learned along the way. I wish I could find something like it to teach the following generations.

Nicely done!

Nice one. The first mod is always the Comp out. LOL. I did a 32K internal RAM mod on one of mine. Total overkill, but it works. (it's the only spare RAM chip I had that was compatible) My other 81 has the now rare Minstrel ZXpand, (a 32K RAM, joystick and SD card interface), that I soldered onto the edge connector. The joystick can be mapped to any keys you want. So I've got 5,6,7,8 and 0 for fire. 👍

Beast indeed !!! My first OWN computer !!!

I spent a long time programming games on this in my younger days before the zx spectrum came along!

Glad you used the internal expansion ram as the ZX81 was very very notorious for resetting itself if you as much as breathed on the ZX81 with the official 16K ram pack. For anyone that has a ZX81 with the 16K expansion pack even Sinclair advised you to put a fairly large roll of blue tack underneath the back of the ZX81 case and a decent blob of it under the ram pack and press both firmly into it once put together. You only then have the problem of leaving your finger prints burned into the keyboard once its "warmed up" lol ( we always joked you could fry an egg on the case/keyboard lol )

I remember the 1k ram pack extension that fitted in the back. If my friends mother opened the fridge door it would crash 😂

i had one of those back in the day before i repurposed it into a mini synth mixer which i still have.

I loved this. It was my first computer.

I bought one in I think 1983. The goal was to use it to plot points in 3D space onto a drawing on a drawing board. I took months ,fighting the 16k wobble box, the wonky keyboard, and the rough NTSC display, but I did get it to work. I wrote a program called "Circe" that I used to lay down very complex 3D draiwings from basically any perspective - it even included a kind of focal-length effect. I used it to draw a ton of things that totally baffled experienced illustrators - like yacht hulls, and internal cutaways of them as well. I the end I made tens of thousands of dollars with that program, which was slow, clumsyy, but accurate enough that I could make it work. I still remember the mode where, after entering the three coordinates, to calculate, the ZX81 gave up on refreshing the screen, which would go blank for a second, before coming back, with the synch not quite right before everything lined up. There on the screen were the two resulting XY coordinates... it was magic.

That was my very first computer and the expansion pack and a standard cassette player to load programs super basic but loved it…

Remember the little ZX81 mines, was the kit you built yourself.

The Timex Sinclair 1000 (ZX81) was my wife's first computer so I've always had a soft spot for it. I do have a ZX81 emulator app on my phone.

The ZX81 was affordable and got me going. Good enough for me.

I have several ZX81s. Two are modified and one heavily. The heavily modified one has 16k internal RAM and an extra socket for video out. The "back porch" is not needed for all LCD screens with video in. I also modified the power so instead of having a red hot 7905 it has a mini-switcher.

Gosh that is a blast from the past. I bought my ZX 81 new with the money earned at my casual job while at school. In those days there were magazines that had programs for you to type in. Then moved on to the Commodore 64 when they became available. Amazing to see they still going. It was quite something in the day.

Jam in the TSR-1 2450. In my TS1000 I dumped the RF box entirely and soldered a gold RCA jack directly onto the motherboard with the composite board held in with a piece of double sided tape.

I can’t believe you went to all that trouble to get composite out of the ZX. I converted TS-1000’s to output composite straight through the RCA jack of the RF modulator with a couple of jumpers.

I had exactly this when I was in grade school. This computer kicked off my love for programming. I had the NTSC as well. I also had the piggy back expansion memory.

My uncle gave me his old ZX81 when he got a newer computer. I remember I upgraded the RAM to 16k and bought a keyboard that basically swallowed the whole ZX81, and I was so chuffed that I had so much memory to program in. The amount you could do with 16k! 😂😂

I've several ZX81's from original to modded, one ZX80 that I'll never part with and practically every computer & console released between 1978 & 1990. My wife loves how my collection makes great use of space in our home 😜

I had 3 OF these one Sinclair and two Timex. Toward the end, you could get one for $20. Countless programmers got started with these doorstops.

I actually had one when I was a kid. My first computer before the Apple 2e

Wow those two games looked really fun. I’m seriously considering getting a spectrum now. I always thought it had boring 2D games. The graphics in that maze game were impressive.

Cool video.

My first computer! I spent hours typing the Basic game programs that were provided in magazines.

had that back in the early '80's... with a cassette player for memory/storage

It's all flooding back. I built one of these from a kit to save money. I built a 64k ram pack with dynamic rame, paging outvthe overlaps with rom etc and wrote a wordprocessor in Z80 Assembler. It never get much use ad I didn't have a printer and saving and loading to audio cassette was just too much foreplay. Those were the days...😂

Homebrew authors have been able to get the ZX81 to do things that even the hardware designers didn't think it could do, like "hi-res" graphics.

This little computer is what led me to ruin my entire life by working in hardware and later, software. May it's RAM pack wobble eternally.

My first computer. Didn't play games on it, hardly used it tbh - it was already outdated - but I did program a kinda trippy visual using a coding book that came with it. Got my speccy 48k not long after and it was confined to the back of a cupboard.

This was my first ever computer when I was a kid. Had it for a couple of years. Even got the 16k RAM pack for it. Would like to get hold of one again. Just to have if I could find a pristine one.

ZX81 or Timex version was the first computer I had my hands on, but I was really way too young to appreciate it. Two years ago I was helping my parents clean out the attic and found a strange circuit board among other old electronic components and sure enough it was the ZX81 without any casing or keyboard. I took it home figured out how to power it up and sure enough I got a prompt It still worked! Did a bit of restoration on it, replaced the electrolytic capacitors, I 3D printed a case with a keyboard using MX cherry key-switches. Did a composite video mod and upgraded the RAM to 16k without the external connection. Fun little project to get the first computer I used working again.

I still have a ZX80 (the one before ZX81). I used to have several but I can only find one. It was possible to run the ZX81 PROM on a ZX80. With a bit of trickery and a larger PROM, I made a ZX80/ZX81 that could be either depending on the setting of a switch. I also came up with a hack that allowed pixel graphics instead of character graphics but it was a bit ugly to use and ate up a lot of the RAM. It also was possible to make an external I/O PCB board for a ZX80/81. This allowed you to turn on and off LEDs or motors or the like with a strange poke command and sense logic inputs with a peek command. Basically, it worked like a RAM expansion but just contained an 8 bit latch and an 8 bit buffer chip. More chips were needed for address decode than anything else.

Congratulations on the successful modification. It's interesting to see how other people have modified their Zeddy. Good job and have fun with it. Another tip from me, there is a ROM upgrade called Big Bang. The Zeddy works faster and better. ;-)