Hi, I'm the designer of the 3d printed case you showed at the end. I wasn't sure anyone would be interested when I first made it, but it seems the ZX81 fan base is much larger than I expected.
@iNimbleSloth Жыл бұрын
Hi Peter, excellent work! Do you have any tips on printing it, orientation etc?
@petermoore4056 Жыл бұрын
@@iNimbleSloth I'm not sure what type of printer you have, but the bottom part can be printed flat on the print bed. But I didn't want the top case to have steps in it from the layers, so I printed mine standing on it's back. An stl in this position is included, but bed adhesion needs to be good. I have a corexy printer so the model only moves downwards when printing, but if you have a cartesian style printer, I would recommend the case top be oriented in line with the bed movement, or it may not print cleanly. You can use supports for the top case standoff pillars if you want them to print cleanly. Other than that it is quite simple to print. There are also feet in the stl files these are optional if you want to use rubber stick on feet.
@onkelnb Жыл бұрын
The case looks great. I might give it a try on my printer. As far as I know, there are still no Spectrum Plus Replica cases around. Any plans on trying something like that? There might be some demand.
@petermoore4056 Жыл бұрын
@@onkelnb Thanks! I ended up making the case myself after being unable to find one that actually looked as close to the original as I wanted. I wasn't planning on any other cases in the near future, mainly due to lack of spare time, but I wouldn't dismiss it as a future project.
@xavierayayaell546 Жыл бұрын
Top man
@dogriffiths Жыл бұрын
Such a magical machine. It looks so uninspiring, but when I was 12 years old this was my first computer, and absorbed my life when I first got it. I learnt to code on it and went on to make it my career. I've written code in C, COBOL, Java, Ruby, JavaScript, Python, and Kotlin, but nothing I've done has given me the same thrill as going through the first few example programs in the excellent ZX81 manual.
@fredjimbob2962 Жыл бұрын
Same, I used to stay up into the early hours on it while the rest of the family was fast asleep. I was about 12 as well I think (born 1970). Went on to study computing at college.
@petewarby7158 Жыл бұрын
Likewise. I was given a ZX81 when I was 12, led me in to a world of tech culminating in some system design that is known worldwide. Simple beginnings. Amazing project, credit to you buddy.
@reaffirmation12 күн бұрын
Same story here.
@MarthallersMisadventures Жыл бұрын
This was my first computer. My highschool formed a computer club and we ordered about 20 of the kits. We waited months for the kits to arrive. On the day that the kits arrived I had to work after school until to 9:00 PM. I started my build when I arrived home and completed my build by about 2 AM. When testing I had an issue where the screen image would role every second or two. I took my completed kit to school the next day and I popped in to see my Physics instructor who was the club sponsor. I mentioned that I was having an issue with my computer. He reached out and put his hand on shoulder and in a condescending manner said, "It's a kit that you need to assemble before it will work". When I explained that I had completed the kit yet still had a problem he was shocked and agreed to look into the issue. Luckily he found the cold solder connection that I had missed. The next person in my club to complete the build was 20 days later. This kit started my career.
@Ernzt8 Жыл бұрын
This is a trip to memory lane! The ZX81 was the first computer in my family, my brother (who is a geek) bought it and I especially remember the frustration when the 16Kb expension lost connection when it moved just a little bit. All lost and start over again... great memories about programming though
@keancv Жыл бұрын
that is why the rest of us bought 3rd party ram packs instead. If I recall right, the wobble was cured by placing a stabalizeing support under the ram pack
@lordlucan529 Жыл бұрын
@@keancv Blu tack! :)
@martindejong3974 Жыл бұрын
@@lordlucan529 No blu tack needed with my clone, as it has 16/32K RAM internally, so 16K RAM with no wobble problems. Also I added angled pinheaders to the edge connector. When designing the peripheral board also with female edge connectors, you will create a very stable connection. for example the PSG (programmable sound generator) with an SD-card interface will have such a female pin header interface connector (but you can also mount a classic card edge connector if you want to use it with a normal ZX-81)
@lordlucan529 Жыл бұрын
@@martindejong3974 Sounds really cool - I might have to tip my cupboard out and find my soldering station and scope and take a look :) What is on the expansion connector - I'm guessing just address, data bus and power? I'm also surprised how few logic chips the ULA amounts to!
@martindejong3974 Жыл бұрын
@@lordlucan529 Yes, the real reason was that for a somewhat easy PCB layout the PCB probably needed to be somewhat large, the main reason though was the cost of the logic chips, which were much more expensive then, especially RAM was crazy expensive although ram rapidly became less expensive, so much so that the american version already had 2K of RAM.
@martindejong3974 Жыл бұрын
Wow! Thanks. I am martin de jong A.K.A. Mahjongg the designer of this clone, and I started this design 38 years after 1981, hence the name ZX81+38! However due to Covid I was unable to finish it until now, although early adopters helped me to fix a few bugs, my revision 1.9 is now fully working. AFAIK you are the first to put a video about my clone on KZfaq! That is great! This is my second ZX-81 clone, the first one (the ZX81+35) used SMT (surface mount) components, but because I got feedback that my clone was great but that SMT was "a bridge too far" for most hobbyists I designed this second one. During my previous effort I fixed all problems with my "ULA replacement logic" and it is now as perfectly compatible as I can make it, and everything I have thrown at it (various highness graphics versions etc) all work, and obviously I fixed the "front port bug" that earlier ULA's had. My replacement logic works with modern TV's, and if you have a CRT it even displays the famous loading bars of the ZX-81, because I did some trickery. Newer TV's just switch to black if they loose the sync signals. I see you are using the keyboard without the paper overlay I have designed. You can download the .PDF of my overlay and print it out (it should be correct to size for my keyboard), it has holes for the key stems to poke through, and all the texts are arranged around them. As you might have seen, not only can you get the Gerber/drill files for a PCB manufacturer, but also a complete BOM with exact order codes for Farnell, Mouser and Reichelt, and I made a drawing showing where all the different components go. Obviously there are schematic's and even the CAD Files (for KiCad 6). Modern 27C256 eprom no longer have the glass window, but are sold as "OTP's" (one time programmables) for much less money. My clone supports 27Cxx type (E)PROMs, but also (with a few patch wire jumpers) 28c512 (EEPROM's), the W27C256 from windex which is electrically erasable (fully 27C256 pin compatible) and even the original ZX-81 ROM. And by the way it has 16K RAM built in! (or 32K if you want that). I know that 27C256 ROMs are affected by the Chip-crisis, but you can still buy an 8K EEPROM (a 28C64) from Reichelt for about ten euro! Just change JP10 so that pin 27 (nWR for this EEPROM) is tied high. If you need support you can mail me at mahjongg AT xs4all.nl. on my maker-space www.revspace.nl , Where I kept an extensive journal about the design process of the ZX81+38 in the projects section. I have just uploaded my take on the cassette replacement unit known as TZXDuino (aka Casino) a minimalistic version without display and with just two buttons instead of five, it was specially designed to build into a sinclair spectrum 48K for a museum I work for, but should work with my ZX81+38 clone too. I'm also planning to release a programmable sound generator (software compatible with the ZON PSG), but my version uses the GPIO port of the PSG Chip (a AY-3-8912) to control (bitbang) an SPI interface, used to connect a SD-Card reader. A german fan has written menu driven software for it which can be placed in the unused second 8K section of the BASIC ROM. he said you can download ".ROM" games (etc) with ten times the speed of a cassette. (a working version already exists for my older clone ZX81+35). This new version will be compatible with ZX-81's and my ZX81+38 clone. Note that I am a moderator on the raspberry PI forum, and I made a thread about my hardware designs, where you can directly comment me its in the "offtopic" section.
@coldsilnc Жыл бұрын
Great to hear. I have checked on your work from time to time but haven't had the time to try out your designs yet. It's really impressive what you've been doing. I will have to build 1 soon. 😀
@iNimbleSloth Жыл бұрын
Hi Martin, Loving your work! The documentation was awesome, especially a BoM containing links to suppliers and part numbers! I couldn't source a modern EPROM due to shortages, the only few I saw were stupid money on eBay, hence the old one. After recording I managed to get an SMD EPROM already soldered to a compatible size PCB to make it a direct replacement, so I'll give that a go soon. Which computer museum are you working at?
@martindejong3974 Жыл бұрын
@@iNimbleSloth The nationaal gamecomputer museum in Zoetermeer (near to den Haag). Strange, that you could not get a new OTP rom, I will look at it, (I did, and can confirm that the 27C256 is hard to get at the moment, but also found an alternative, in the 28C64 EEPROM, which can be bought from Reichelt, you can use it in my ZX-81+38 by using JP10 to tie pin 27 high). I also heard someone mentioning that the 1/4 Watt resistors I am using are far too large. I am constantly updating such small issues in the BOM. For me it is a a long time commitment, and will perhaps start selling kits also in the future. Nice that you think my documentation is good, I'm still planning to add a building guide. But seeing that without one many people manage to get it working its "good enough" at the moment. I did not see you use the component placement drawing, didn't you need it?
@iNimbleSloth Жыл бұрын
Awesome, I was in Amsterdam a couple of months ago for a few days with work and wanted to go to this museum but with the flight times I didn't get a chance to. Still there is always the future!
@MattKasdorf Жыл бұрын
🤔 Next revision... integrated Z80 ROMulator 🤫
@chuckrose38948 ай бұрын
In high school, I took a vocational computer course (3 periods a day for 2 years) in which we used a PDP-8e. I wanted to buy a computer once I graduated and the only thing I could afford was a ZX81 (not a T/S 1000 as most Americans have). So I ordered it as a fully built machine with the 16k RAM pack. The first computer that I actually owned. I used it to it's utmost for a year or so (velcro used to keep the RAM pack connection in place). I think the only commercial software I got for it was Flight Simulator from Timex/Sinclair. But I must have written 100 or so games and application software for it in BASIC. I always thought the ZX81 or the T/S 1000 BASIC language was quite powerful for it's day. It had various commands and statements that weren't even included in the DEC PDP-8e BASIC that I was taught in school.
@captainchaos3667 Жыл бұрын
I still have my ZX81. 😀 I learned to program on it when I was seven or so. Love it to bits, this is really nostalgic for me.
@mikeyoung9810 Жыл бұрын
Same. I used to write some big games on it despite that touchy 16k memory pack which if it shifted could cause the entire thing to reset.
@dogwalker666 Жыл бұрын
Me too, And I bought the kit version originally. True blast from the past.
@horusfalcon Жыл бұрын
Nicely done! I understand the interest in the ZX-81, as it was the first computer I could afford to buy, and it still has its own special charm today. It was a machine that encouraged tinkering, and tinker a lot of us did. Thanks for the memories (cue Bob Hope).😀
@cigmorfil4101 Жыл бұрын
The original ZX81 keyboard was ridiculed for its flatness, lack of feedback, etc. Now we have gui interfaces which no longer have buttons that look like buttons but just flat bits of coloured screen - the "modern minimalist look"...very much in the style of the original ZX81 keyboard. Tge ZX81 keyboard was clearly so ahead of it's time...
@theforthdoctor7872 Жыл бұрын
Outstanding. As a child of the 1970s I cut my teeth on the ZX81. When you started test program at line 1, I could hear myself screaming..NOOO....lol
@iNimbleSloth Жыл бұрын
I know I know, 10s are better, then you can insert lines in-between if needed. But I like to live dangerously 🤣
@Auberge79 Жыл бұрын
RENUM 10 [L] Press Enter ;-)
@bomberaustychunksbruv4119 Жыл бұрын
Had one. Learned Basic with it. Had the Ram Pack 16K and the thermo printer, I used to print off Menus for Hotels way back they thought it was DA BOMB. !!! hahah.
@BigCar2 Жыл бұрын
Fascinating video - thanks! It would have been interesting to have a commentary during the build telling us what's going in and why, to describe more about how this recreation was designed and produced.
@iNimbleSloth Жыл бұрын
Thanks for the feedback. It's not my design but you'll find more info here Github - github.com/mahjongg2/ZX81plus38 RevSapce - revspace.nl/ZX81plus38_simple_to_build_ZX-81_clone
@espenbgh2540 Жыл бұрын
I'm deeply impressed of your speed soldering and assembly of the ZX81
@martindejong3974 Жыл бұрын
Its slightly speeded up DUH!😘
@SilverSergeant Жыл бұрын
I learned Basic on a Sinclair ZX81. I had the memory expansion and a printer!!!!
@dodgydruid Жыл бұрын
Thing is, back in the day with the ZX80 and ZX81's was after a good while of use you had a series of burnouts on components so by and large they ended up partially all new under the hood because of the incessant heat death of the bloody machines which the Spectrum never suffered from. I remember WWIII over my ZX80 scorching my new bedroom carpet, that thing melted and burned out almost daily and the plastic on the expansion pack often turned brown and sagged weirdly. We were lucky in up the road from us there was an early RS Components shop and he was always able to get in bits and pieces fairly quick and the shop owner was a Sinclair nut too so helpful in keeping these ticking time bombs from blowing up :D
@Tutorius Жыл бұрын
I have bought a timex-sinlair-zx81 on 09 of August 1984. It had a price of 49 Deutschmark. On the next day i had a motorcycle-accident driving from my job to home. I had a kidney-rupture and stayed in hospital for about six weeks. My oder brother found this ZX81 at home and bought a thing for it, it was called "Azmic-ROM". It was a total change of the system, no more basic, only Z80-Assembler. I knewd the mnemonics of 8080 and Z80 cause we had a self-constructed comp at home, so i wasable to write asselmbler-programs in my clinic-bed, the little ZX on a plasic-bench on my bed. Later i wrote "Wurmi" on my Oric Atmos, that i had bough some month befoe the accident happened....
@GPL04 Жыл бұрын
And without a wodge of Blu Tack to deal with the RAM pack wobble!
@diond1333 Жыл бұрын
A friend of mine still has his Spectrum 128k with all the accessories it originally came with, housed in its original box in his mum and dad's loft. I'm just waiting until they go on holiday........
@muppeteer Жыл бұрын
My first computer...crap by todays standard but loved it
@JoseSilveira-newhandleforYT Жыл бұрын
This brings back memories! I built the ZX81 kit version when it was made available. My first computer and a lot of fun 🙂
Жыл бұрын
Brilliant!! This was my first personal computer. The experience of programming the ZX81 Basic was much more fun than programming COBOL on a mainframe. The iconic design of the machine and the keyboard still seem second to none in my opinion.
@javilarg11 ай бұрын
Identification Division. 😂
@ehsnils Жыл бұрын
Next up would be a new incarnation of the Swedish ABC80 computer. It was more competent but used a Z80A processor at 3MHz with 16k ROM and 16k RAM.
@dogastus Жыл бұрын
Reminds me of way back in the 80's we found a source of ULA chips for the Spectrum so managed to make a working unit. We hand-wired it on a patch card and used a mechanical keyboard rather than a membane. It was great playing those old games with it like Attic Attack amongst many others.
@scottb4029 Жыл бұрын
Brings back memories, my friend Seth and his dad had a ZX 81 he assembled , since I was in the states the next year my mom and stepdad bought me a Timex Sinclair 1000 , I eventually got a 16k pack. Then I enjoyed the true frustration of looking hours of work and data because of my heavy fingered input and a battery pack that had slowly walked its way out. Good days.
@mibnsharpals5 ай бұрын
In principle you could recreate the ULA with an FPGA, then you would be with the original ZX81. So it is a ZX80 with NMI extension, which is also much easier to implement and is still timeperiod correctly (there was an extension for the ZX 80)
@MrBartleby451 Жыл бұрын
I remember a teacher at primary school got hold of a ZX80 and and ZX81. It was a thing of wonder and started a lifelong interest in technology and computers. A year later we got a ZX Spectrum 16k at school still remember the excitement now.
@Gordon705 Жыл бұрын
I appreciate your historical accuracy I wouldn't have faulted you if you had hardwared around the 16 bit addressing.
@madcommodore Жыл бұрын
Well clearly without the original keyboard and case being 100% identical it's just the naff motherboard you've recreated ;)
@stuartwalker16 Жыл бұрын
I love how u have ur hands in time with the music nice wee touch ❤️😁😁
@kubuspuchatek4730 Жыл бұрын
These screen tearing artifacts are caused by poor voltage filtering by the 5V regulator (LM7805) which is overheating. I removed them by unwinding 10 turns of the secondary winding of the transformer in the power supply from the transformer. It is also good to replace the heat sink plate with a larger one and stick the heat sink on the ULA. After such a modification, my ZX81 has been working flawlessly for years. Te artefakty szarpiące ekran są spowodowane złym filtrowaniem napięcia przez stabilizator 5V (LM7805), który się przegrzewa. Ja usunąłem je poprzez odwinięcie z transformatora 10 zwojów uzwojenia wtórnego transformatora w zasilaczu. Dobrze jest też wymienić blaszkę radiatora na większą oraz nakleić na ULA radiatorek. Po takiej przeróbce Mój ZX81 działa od lat bez zarzutu. Greetings from Poland - the most free and beautiful country in the world
@Spookieham Жыл бұрын
I've been playing with computers for 40 years and made a very successful career as a software engineer and it all started with a ZX81
@ferrumignis Жыл бұрын
Me too! I still have my original ZX81 and the Dragon 32 that I got a bit later.
@newmonengineering Жыл бұрын
Almost the same, I had all 3 1980 Era computers at some point, TI99, VIC20 and Sinclair. I programmed all of them for many years over time became a database guy and am a manager /dBa now. Those old computers produced a whole generation of us for sure!!
@martindejong3974 Жыл бұрын
I started my career with a KIM-1 a 6502 based single board computer. My second one was a kit, the LNW-80 a TRS-80 model-1 clone. (with color graphics). I built many ZX-81 kits as that was one of my jobs back then, I also built acorn atoms, and updated 16K TRS-80's to 48K RAM.
@mikeyoung9810 Жыл бұрын
That sure brings back memories. I mail ordered a timex sinclair 1000 in the early 80's from England and it was my first computer. I loved that thing. edit: I had it in my head it was 4k without the memory pack (which loved to shift and reset the computer). I also had the thermal printer with those long paper strips it produced. I only owned 1 game, a flight sim. But I wrote so many games with it and learned basic from it.
@lostcarpark Жыл бұрын
That's awesome, though a ZX81 built from discrete components instead of a ULA sounds more like a ZX80 to me!
@martindejong3974 Жыл бұрын
Maybe, but its is fully compatible with a real ZX-81
@lostcarpark Жыл бұрын
@@martindejong3974 I think there was very little technical difference between the ZX80 and 81, apart from moving discrete components into the ULA. I think there was also a NMI added to the ZX81 to support SLOW mode. Apart from that the only difference is the ROMS. I think you could put a ZX80 ROM in one of the banks of your ROM chip and you ought to have a working ZX80.
@martindejong3974 Жыл бұрын
@@lostcarpark Back in the day the company I worked for offered a service for ZX-80 owners to add a ZX-81 ROM (actually an EPROM) to your ZX-80, it offered all the features of a ZX-81, except slow mode, so you did not get the feature of the ZX-81 to keep the display while running BASIC. Actually I did the ROM conversions myself. Must have been a few dozens. I also was able to convert a TRS-80 model 1 to an 48K RAM model by replacing the RAMs in the main computer, so for 48K RAM you didn't need and expansion interface. I'm the designer of this clone, and it took a lot of tests and experimentation to design the ULA Replacement logic, so that my clone is fully compatible with a real ZX-81, meaning that it can also run "high resolution games" and such. It also has the modification so that it works well with modern TV's, and I added a cassette pre-amplifier to make loading cassettes a lot easier, and added a joystick interface that converts joystick actions to keypresses on keys 5, 6, 7 , 8 and 0 (left, down, up, right and fire). Oh and it has 16K (or 32K) of RAM built in, so no ram wobble problems!
@lostcarpark Жыл бұрын
@@martindejong3974 Thanks for the explanation. Would you need anything other than a ZX80 ROM to go the other way - from ZX81 to ZX80?
@martindejong3974 Жыл бұрын
@@lostcarpark I'm not sure, I never tried. Its much easier to design a ZX-80 clone, so they have existed for some time.
@thomaswalther7276 Жыл бұрын
Great video! Maybe it IS now time to finally solder the ZX81 DIY Kit I stil have in my basement ...
@Antonio_Gallego Жыл бұрын
My very first computer, I'll always remember the first time I tuned my TV to channel 36 UHF and saw the magic cursor.
@marimarmarimar25 Жыл бұрын
Wunderbar peoples who posted here. I'm also a Z80-holic. 🙋♂️ 👍 Thanks for the video, you are goood!
@JediBuddhist Жыл бұрын
I'm in.! Have a grandchild to lookafter and 347 other jobs i'm avoiding but I think this one can jump the Q. Top Banana.! Thanks
@SpiritmanProductions Жыл бұрын
Great project and video 👏, but who else is triggered by line numbers 1 and 2 instead of 10 and 20? 😁
@stevesgaming7475 Жыл бұрын
Very cool indeed!
@JavierRoitman Жыл бұрын
A ZX81 made with TTL logic instead of an ULA , that could be the Brazilian made TK83. That thing heated a lot and had some rare compatibility issues with software that pushed the limits. Anyway, well done! This machine put me and many others into computers back in 1982
@robertdrinkall8947 Жыл бұрын
Great in it's day, but that day has gone, let it rest in peace...............
@iNimbleSloth Жыл бұрын
But nostalgia...
@raysrcsandtech Жыл бұрын
Awesome the ZX81 was my first computer as a kid, remember going into Debenhams with my dad to get one, we went back a few weeks latter to get the 16K RAM pack. Happy days, I latter went to VIC20 (didnt like much) then moved to Atari 600XL and never looked back.... going on to own every Atari made, then I moved to Psions before ending up with Mac
@BerniesBastelBude Жыл бұрын
cool project! - the ZX81 was my very first computer, and i didn't even remember what happened to it...
@r1273m Жыл бұрын
I still have a couple of ZX81's somewhere in the garage, along with power supplies, 16k memory units and various interface boards I built back in the early 1980's. Maybe I should get them out and put them up on Ebay, I never imagined people would still be interested in them.
@iNimbleSloth Жыл бұрын
Cool - Nice to keep at least one 😉
@paulromsky9527 Жыл бұрын
Great video. My ZX81 still works, I have the 32K RAM pack, and printer. I have a small LCD monitor that accepts RF TV channel 2 NTSC.
@paulromsky9527 Жыл бұрын
For the Dogsbody (ULA) - at least the digital parts of it, I would use a decent Xilinx FPGA with lots of CLBs and routing. I would clock it at the same speed as the Z80 (or maybe faster). This way I could code it to do exactly the same functions. A lot easier than a bunch of discrete logic and it can be changed as needed. It could also be possible to have added features - like an interface to use a PC as an In Circuit Emulator for the Z80 CPU. In fact, the ZX81's RAM, ROM, and even the Z80 CPU itself could all be implemented in a single massive FPGA with today's technology. The heart of the ULA was (along withe some "glue" logic) effectively a interrupt driven DMA from from RAM (the characters on the screen), and ROM (the 5x7 bit patterns for each character pattern) directly into the ULA so the bit patterns could be shifted out to the TV Modulator. I would use a fully digital FPGA with 3 video output signals to generate NTSC (or whatever): 1 for Sync (Blacker than Black), 1 for the Sync Porches (Pluge), and 1 for pixel Off (Black)/On (White) level. So a simple analog circuit would be used to generate those levels in real time from the FPGA to the Modulator. So: 1 FPGA, 1 High Speed Analog Video Ciruit, an RF Modulator, a Keyboard, and a Power Supply. I might even be able to make the Screen RAM portion dual port so the CPU can run in Fast Mode but display video at the same. To see screen video while running, the ZX81 had to "steal" code processing time during the video Syncs (Slow Mode) - the result: The code/editing "appeared" to run in real time with constant video, but since the RAM was not dual ported in the ZX81 (to keep it low cost) the BASIC code ran much slower in that mode. The Whole thing would be roughly 1/5 the size of the ZX81.
@TheTurnipKing9 ай бұрын
There's a couple of ways to solve the issue depending on what exactly you want to achieve and at what cost. if you want to use actual hardware, you can actually use the ZX80 schematic constructed out of 74 series logic in place of a ULA. There are even modifications you can make to support the ZX81 fast/slow mode. Far cheaper is just to emulate the whole damn machine on a much faster CPU. It was fairly possible to emulate it on an old Atmel microcontroller, and is certainly relatively trivial on a modern ARM based mictocontroller.
@paulromsky95279 ай бұрын
@@TheTurnipKing My idea was to emulate the ZX81 to work just like the original hardware, then improve on it. I coded and simulated the ULA in VHDL and it looks like it could be a drop in replacement, is was easy and it should fit in a fairly small FPGA. I did not implement the Z80 CPU in VHDL because I can still purchase them, as well as RAM and ROMs. Cost is not an issue, it is just a "what if" project. My next step is to design a PCB for it. JLCPCB can make low run PCBs (about 25 or less, they will even make only one and only charge you $5 for the NRE) for about $2 a board. A quick upload of the Gerber files and away they go. I have used them before, very high quality, it just takes 3 weeks to receive them.... mostly shipping time.
@TheTurnipKing9 ай бұрын
@@paulromsky9527 A excellent solution for your intended usage, especially since you intend to make use of the FPGA to extend the design later.
@paulromsky95279 ай бұрын
@@TheTurnipKing I use the ZX81 ROM unchanged. Also, I changed the Keyboard to use a USB keyboard. The ROM code is still the same, the FPGA just emulates the membrane Keyboard from the USB keyboard data. The Tape recorder is no longer used. The FPGA still handles what the ROM expects for SAVE/LOAD, but the external interface is to USB not a tape recorder. Instead of tones, the USB is a stream of ASCII '1's and '0's. This allows programs to be stored on a PC (with a simple app I can write). This makes storing and loading much easier as you don't have to queue a tape, just select files on the PC. I can even use a Flash Memory Stick for program storage (if I use an FPGA with an ARM core). However, I could not make load/saves faster because the ROM still thinks it is talking to a tape recorder. This also removes that crazy screen seen during load/saves. My FPGA has dedicated video out so it just puts out a blank raster when loading/saving. Also, it's no longer composite video to an RF modular, it's composite video to HDMI. No more need for UK/USA/France modes as I think HDMI is standard in any country for any TV that accepts it. I am calling it ZX81-Y2K as it is designed for peripherals (keyboard, monitor, program storage) that are now available in the 21st century. It will also come standard with as much as the 64Kbytes RAM as the original ZX81 handled. Using SMT, the whole PCB will be about 75% as large as the original. It will still have the old board edge contacts for peripherals (like a ZX80 printer) but I will have a provision for a ribbon cable connector to eliminate the old "wobble" reset.
@TheTurnipKing9 ай бұрын
The rationale behind having the fast/slow toggle in BASIC was the ability to turn the screen off if faster compute was required. The Spectrum "solved" the issue by basically giving the ULA priority over the first 16k of RAM so it always had first dibs on the screen ram. On the 48k anything in the upper 32k runs at full speed.
@Locateson Жыл бұрын
You need the shoutout to the PCB maker, of course, but you can make something like the ZX81 or replicate it on a breadboard even today. At the clock speeds you can get away with nearly everything. It's also amazing how many PDIP logic ICs you can still order today.
@basfinnis Жыл бұрын
Great effort. Looks great 👍
@JeromeFortias Жыл бұрын
Just fantastic ! You made my day with this video Thanks
@kevincozens6837 Жыл бұрын
IIRC, I used to have the schematic for the ZX-80. I don't remember the differences between the 80 and 81. IIRC, the 80 used standard parts so it could be used as a guide to avoiding the need for the ULA in an 81 recreation.
@darkmatter7274 Жыл бұрын
I've still got my zx81. With printer and 16K module.
@giloc Жыл бұрын
Wow, i begin programing with that kind "computer", very good memory in my head. My fist software was "PacMan Game". Thanks
@frombrum Жыл бұрын
i have my original zx81, printer and ram pack still working when i last tried it trying to find games in mp3 format to replace the tape machine
@captainchaos3667 Жыл бұрын
Tip: you don't have to type a space after the line number. 😀
@captainchaos3667 Жыл бұрын
Or anywhere else before or after keywords really. Only inside string literals. Same goes for the ZX Spectrum.
@screen-protector Жыл бұрын
To be true, I'd use a bit of flux and a soldering paste. Insert few components and just use a hot air :D. But, if you enjoy that, I see why not. I've got too many electronics repairs to spend so much time on hobby :).
@othoapproto9603 Жыл бұрын
That was my first computer 1980
@wisteela Жыл бұрын
Superb. Subbed. I really could see a market for pre-built ones, especially with keycaps with all the keywords etc. Reminds me of the Soviet clones.
@grahamlewis6777 Жыл бұрын
looking forward to ep2!
@martindejong3974 Жыл бұрын
me too! 😄
@BrumKid Жыл бұрын
My very first computer was the ZX81and was in kit form, it took me about an hour to build it worked. Over time i expanded it and even made my own keyboard and made a wooden case to put it all in.
@iNimbleSloth Жыл бұрын
Do you still have it? I’m thinking of designing a mechanical keyboard for this one and trying to decide what to do for a case. Wood is appealing for a true retro themed home brew feel.
@BrumKid Жыл бұрын
@@iNimbleSloth Sorry no when i got the ZX Spectrum i sold it 😢
@wildpat03 Жыл бұрын
@@iNimbleSloth If you're interested, I'm a hobbyist woodworker and the ZX81 was my first computer. I'd be game to build a wood case for your project. Let's talk?
@iNimbleSloth Жыл бұрын
@@wildpat03 Sounds cool, thanks for the offer. You can reach me at info@inimblesloth.com and we can work out logistics etc.
@madcommodore Жыл бұрын
I remember launch RRP as £79.99 oddly
@mcdougles Жыл бұрын
I'm working with mainframes now, but I missing my ZX Spectrum...
@kleverich2 ай бұрын
Technically specs were somewhat lacking for 1981.
@jesuisledocteur Жыл бұрын
I was yong when i work with this computer ( basic language..)
@mad_circuits Жыл бұрын
Subscribed. This is for the algorithm.
@paultomlinson528 Жыл бұрын
Famtastic
@stuartwalker16 Жыл бұрын
I had a 16k memory pack on the back lol 😆
@TimBabcock642 ай бұрын
I wouldn't mind running a Raspberry Pi on a Sinclair case with a traditional keyboard (no chicklet or membrane keys).
@MrFlint51 Жыл бұрын
I moved my ZX81 into a proper case with a clicky keyboard and wired the 16K rampack to the extension port with a ribbon cable. There was a circuit called "High Resolution Graphics"(HRG) published in one of the Sinclair magazines which allowed you to switch the 1kRAM into the ROM address space for the character set, giving 16 8x8 sprites. Have you considered replacing the 1K Ram with a bigger one up to 64K?
@chaos.corner Жыл бұрын
I have a 64k rampack built by a company named "Jigsaw" from out of Petersfield. It was originally supposed to be a 32k but didn't work so they invited me into their office and tested it and it turned out there was something wrong with the design or soldering so they gave me the 64k instead. I tested that it worked as advertised but never found a use for the extra memory. Sadly it's a bit worse-for-wear now and the edge connector is broken and that's hard to find a replacement for.
@martindejong3974 Жыл бұрын
My clone has 16K RAM, but with the same RAM chip you can also have 32K or RAM, (not really useful as there is no software that uses more than 16K) and my keyboard also has clicky keys, I made an improved keyboard overlay with the texts moved around a circle though which you can stick the key button through, but if you use "low travel" buttons you don't need to make holes in the overlay.
@give_me_my_nick_back Жыл бұрын
it must have been a great children gift to have fun soldering it altogether during the xmas break :D
@hywelw Жыл бұрын
One other design you could have possibly tried if you couldn't get that PCB is to clone a ZX80. I had one of these (as well as pretty much all the other Sinclair machines up to the Spectrum+) and essentially hardware wise they're very similar to the point that the ZX80 will run the ZX81 ROM pretty much flawlessly with the exception of SLOW mode, which the ZX80 hardware didn't natively support, thus making almost all ZX81 games unplayable! THE ZX80 is almost the the same as a ZX81 but with no ULA chip - made from discrete off-the-shelf components, hence many more chips and components on the PCB (and at the time more expensive). At one point a company did come out with a kit to provide SLOW mode on the ROM upgraded ZX80 which I bought - however my soldering skills were never very good and I managed to destroy my ZX80 when some solder crept under a chip and shorted out a circuit. Shame really, as a working ZX80 is now worth a fair few quid. Mine did also overheat (from the beginning) and this caused it to switch from 50Hz to 60Hz display (or jump and flicker between them for no reason) - not a big deal as my b&w telly coped with both frequencies. Someone also came up with a software only SLOW mode for the ZX80 (running the 4K ZX80 ROM) to prevent screen flicker - however that didn't work on the ZX81 SLOW setting and was intended for custom made machine code software for the ZX80 (of which there was very little available indeed!). I wouldn't be too surprised if that board you bought was heavily based on the ZX80's architecture. Incidentally, if you can get a ZX80 ROM image - this runs on a ZX81 too. One other interesting fact - all the Sinclair products were completely unshielded. Not generally a problem but at the time I was also into CB radio (the original legal version in the UK) and keying up a CB transmitter anywhere near the computer would cause it to go crazy and usually completely crash or reset, and that was just 4 watts of TX power! These days I use a laptop right next to my 400 watt ham radio transmitter - no problems ever encountered!
@iNimbleSloth Жыл бұрын
You might like this then kzfaq.info/get/bejne/eJyZf9tnp6mbmqc.html it's a ZX80 clone designed by Tynemouth Software. And here are some new games that were written for the ZX80kzfaq.info/get/bejne/bNGmrcpe2M-7ipc.html which are able to be flicker-free :-)
@mrpappa4105 Жыл бұрын
Great video im a subscriber now. Where can i get that grey desk mat with the small "pockets" that is used when soldering? Good work, thanks.
@iNimbleSloth Жыл бұрын
👍 I got mine from Amazon, search “soldering mat ” on their site and there are loads of them to choose from. Not too expensive, starting at around £15. Sometimes the small pocket are handy for screws when taking something apart, but on the whole, I found they just seem to attract dust.
@TimWalton0 Жыл бұрын
A hello world example using line numbers 1 and 2 instead of 10 and 20? Controversial! 🙂
@iNimbleSloth Жыл бұрын
I know right 😉
@3dhYT Жыл бұрын
Interesting channel 👍👌
@warheaven999 Жыл бұрын
it was my first PC !
@sobertillnoon Жыл бұрын
USB-B port for power? What a monster.
@martindejong3974 Жыл бұрын
Its the best connector that can be used with an USB charger, but it is still a pin through hole connector. Also it is not really much bigger than alternative power connectors, like a barrel connector. It actually fits well inside the original ZX-81 case.
@sobertillnoon Жыл бұрын
@@martindejong3974 oh my god, seriously? I was making a joke. A joke the video author got. Yes I know the advantages of USB b connectors. You must be real fun in social situations. Also, let me explain the joke for you to make things easier: USB b cables were never popular enough for their ubiquity to drive down the price. So in the early 2000s, USB b cables were a) hard to find and 1) expensive. So yeah, a lot of people have a built in negative reaction. That's the joke. Thanks for playing.
@RichSzerman Жыл бұрын
So does this new version show the loading lines on composite display? Thanks
@iNimbleSloth Жыл бұрын
The loading lines are kind of “emulated” by the logic, and it does depend a little on the TV. One of my TVs does, the other doesn’t.
@Chiavaccio Жыл бұрын
👏👏👍
@perseverance8 Жыл бұрын
Around 12, or so, years ago I purchased a number of ORIGIONAL new old stock ZX81 kits from “zebrasystems”, I’ve yet to build any of them & would NOT use the included electrolytic capacitors in the original, now, nearly 40 year old kits, just replace them with fresh new caps. The ULA is the only custom IC in the ZX81 which can be reimplemented & replaced with 74xx series logic.
@martindejong3974 Жыл бұрын
my design only has two electrolytic capacitors, but many 100nF decoupling caps, and a few ceramic caps for the crystal oscillator.
@perseverance8 Жыл бұрын
@@martindejong3974 Have you ever played with any of the east European Sinclair spectrum clones such as the Harlequin 128k?, I’ve contemplated snagging one up. Currently I’ve been on a kick building 6502 & 65816 based SBC’s, prototyping using soldorless breadboards with a final build using wire-wrap, though wire-wrap supplies have become more difficult to source & co$t prohibitive vs having PCB’s made over recent years, fortunately I have accumulated quite the wire-wrap socket & misc. hardware stockpile also wire-wrap is more difficult to attain higher switching speeds I’m looking for over a half decent PCB layout but not nearly as bad with breadboards, damn capacitance!
@iNimbleSloth Жыл бұрын
I’ve build a Harlequin 128k kit. Real nice, fits in to a replica 48k rubber keyboard case. If using the tuner keyboard case, make they do a specific one for the Harlequin 128 in terms of hole size and position at the rear of the case.
@martindejong3974 Жыл бұрын
@@perseverance8 No never tried to build any of the many Russian spectrum clones, I do know of the harlequin. one of the reasons to built a ZX-81 clone is that there are already so many spectrum clones. and a few ZX-80 clones. One of the tasks that I found fascinating was to reverse engineer the ZX-81 ULA logic.
@javilarg Жыл бұрын
My first computer, with 16kb expansion 😮
@Dr_Mario2007 Жыл бұрын
ULA can be substituted with FPGA if you want it to be just like its original counterpart. The best part is that ancient 8-bit CPUs are still made so you can hop onto Digi-key and buy either 6502 and Z80 or both today, this kind of stuff is popular with hardware hackers who want to roll their own computers if they want it simple, before even graduating to 68k or x86 processors, something like that.
@ferrumignis Жыл бұрын
If you are going to use an FPGA you might as well include the CPU within it as a soft core. In fact this has already been done, have a look for "ZX81 MiSTer Core"
@Dr_Mario2007 Жыл бұрын
@@ferrumignis Yes, I know, however there are some folks who like doing it the hard way, ie. using the original CPU as whole - there's something about soldering up your own project that a larger FPGA chip can't replace. There's cheaper FPGA, ICE40, which you can just use for glue logics with voltage translator to separate 5 and 1.2 Volts IO, and that's pretty much it.
@martindejong3974 Жыл бұрын
@@Dr_Mario2007 I didn't want to use an FPGA as they are "black boxes"
@harvey66616 Жыл бұрын
@@martindejong3974 _"I didn't want to use an FPGA as they are "black boxes""_ -- more so than the ULA? Don't get me wrong. I think there's something really appealing to breaking out all the ULA functions as discrete components. But it's not like the ULA wasn't an integrated circuit hiding all that discrete functionality in a black box either.
@martindejong3974 Жыл бұрын
@@harvey66616 No, but why should future ZX-81 lovers keep inventing the wheel? The ULA has never been fully documented (AFAIK) and by doing it this way the schematic of my ZX81+38 IS fully documenting what functions the ULA contained. Also I released the CAD files, so if someone wants to alter my ULA logic they can. And as for the question if my ULA logic IS fully compatible with the original ULA (or rather the latest version of it, as the front port logic was later added) my ULA was tested by throwing everything to it that I found, and the logic ran everything, so the proof of the pudding is in the eating. It is possible that someone finds something that my ULA doen't do, or find a bug, but my design is fully open source, so it can be changed quite easily.
@adonian Жыл бұрын
This looks like fun... Exactly what files do I need to send to pcbway? so I can give it a try?
@iNimbleSloth Жыл бұрын
I am on a business trip until Saturday so will get back to you on the weekend.
@iNimbleSloth Жыл бұрын
Hi Adonian, you will need the gerber files for the main board, the keyboard gerbers are optional as you can use a ZX81 membrane keyboard which are still for sale if you prefer. The gerber files are located on the designers github page - github.com/mahjongg2/ZX81plus38 The files to download are "ZX81+38 rev 1,9 production files.zip" (main board) and "ZX81+38_ keyboard PCB production files rev 1,2.zip" (keyboard). Both are zip files (no need to extract once downloaded) that you can upload directly to PCBWay (www.pcbway.com/QuickOrderOnline.aspx), just click the "Add Gerber File" button and upload one zip file once at a time. Have a play with the colours of the PCB to see the difference in price. All other settings can be left default, except, in my opinion, the "Surface Finish" should not contain lead.
@adonian Жыл бұрын
@@iNimbleSloth awesome 👏 thx 🙏
@Capohanf1 Жыл бұрын
Do NOT need to build a new one!!!!!!!! I have 3 or 4 of the original Timex-Sinclair's sitting around here somewhere!!!!!!!
@NZ2Pepper Жыл бұрын
Very interesting, thanks for sharing. 1 question if I may, why is it necessary to fill the eeprom with duplicated content? Or did I misunderstand?
@iNimbleSloth Жыл бұрын
There are jumper settings on the board to select a particular 8k bank within the EPROM. I was being lazy and didn’t want to bother worrying about which bank was selected, so whatever jumper selection, then the device would still boot and run the zx81 rom image.
@martindejong3974 Жыл бұрын
Its not really necessary, unless the highest two address lines of the EPROM are unstable (floating) but they are not in my design if the jumpering for a 27C256 is used as is default, then only the first 8K is always selected. But just for security you can fill all three other 8K regions of the 32KByte with the same code. There is a jumper that selects between an 8K ROM-space or a 16K ROM-space, so if you want to use a larger ROM than the ZX-81 has then you can, in that case you can have two different 16K ROM's.
@MattKasdorf Жыл бұрын
Excellent! Did I miss a part where you spoke about sourcing parts? Has anyone done a video on JCWolfram's AX81, a ZX81 on an Atmega?
@iNimbleSloth Жыл бұрын
You’ll find a bill of materials on the GitHub page, the link is in the description. The BoM includes links to suppliers. I’ve not come across the others you mentioned. I’m going to have a look into them now 🤓
@meneerjansen00 Жыл бұрын
@@iNimbleSloth I cant open the BOM. They are "ods" files. No idea which application to use to open 'm...
@iNimbleSloth Жыл бұрын
@@meneerjansen00 It will open with the latest Excel or Open Office or online here odfviewer.nsspot.net/
@meneerjansen00 Жыл бұрын
@@iNimbleSloth Aha! Thanks. It's a "Open Document Sheet" i.e. a Libre Office Calc spreadsheet.
@martindejong3974 Жыл бұрын
The BILL OF MATERIALs (BOM) file contains exact part numbers for Farnell, Mouser and Reichelt. There is also a drawing indicating where on the board each part goes.
@jamesdecross1035 Жыл бұрын
Q: at 1:25 does that mean you're actually building a replica ZX80? That had a series of logic chips replaced by the ULA.
@iNimbleSloth Жыл бұрын
No, not in this instance. The logic chips are equivalent the ULA functionality which is different to the ZX80.
@clangerbasher10 ай бұрын
This with a Forth ROM?
@ShieTar_ Жыл бұрын
Not to be rude, but why is the question today "Can you build a ZX81" ... Why isn't it "How much Computer-Fun can you make for 69 money (or 290 money) today"? Seems to me like that would be a better use of clearly rather capable electronics designers/wizards.
@JamesWhite-yj7sd Жыл бұрын
i still have this computer i lost the 16k adapter
@SIDCIAVIC Жыл бұрын
Why? When an appropriately-sized right triangle of wood could stop a door just as well? ;)
@iNimbleSloth Жыл бұрын
🤣
@theblackswan23733 ай бұрын
Can I use it for a device controller?
@phil2768 Жыл бұрын
Brilliant! I would love to do this. What was the total cost of all the parts?
@iNimbleSloth Жыл бұрын
I had a few bits already but spent around £35 on components. The PCBs were supplied free of charge by PCBWay as they sponsored this video. But 5 x main boards (minimum order) would be around £38 from them plus delivery. And, if you wanted the keyboard, then around £30 for 5 x boards. You can pick up a new zx81 membrane keyboard for around £15. Was a good build, the designer did a great job.
@gartmorn Жыл бұрын
Interesting build. I’ve just sent for a zx81 from an eBay seller sold as untested! At worst I’ll have a case for an emulator!
@iNimbleSloth Жыл бұрын
Be interesting to hear how you get on with it.
@gartmorn Жыл бұрын
@@iNimbleSloth I’ll need to do homework to see what checks I can do with my multimeter and logic probe as I don’t have a scope. Just hope I’ve not bought a dog! I would like it to be as original as possible but I’ll just have to keep my fingers crossed!
@coldsilnc Жыл бұрын
@@gartmorn The zx81 is very sturdy except for the keyboard, so there's a very good chance it's ok. The ULA is the other failure point as it gets quite hot, so put a heatsink on it and it should be ok for years to come. The RF signal is quite bad, but there's an easy reversible mod to make it a composite signal instead.
@gartmorn Жыл бұрын
@@coldsilnc thanks for that. Yeah, I’m sure the composite mod will be on the cards!
@media_dept Жыл бұрын
Is there some way we're supposed to somehow hang on and cope in any way before Part Two of this? 😳
@iNimbleSloth Жыл бұрын
my back catalogue 😁🤣😘
@vinyltheif Жыл бұрын
When you say "get quality pcb's" I presume you mean 'good' quality.
@stuartwalker16 Жыл бұрын
Also who do the music it's really gd !!❤️😁😁
@iNimbleSloth Жыл бұрын
Music is elements.envato.com/epic-and-inspirational-6LVZPA4 by user elements.envato.com/user/Antarctic
@stuartwalker16 Жыл бұрын
@@iNimbleSloth thanks will have a listen great video a lot of work much appreciated 👍
@preferredimage Жыл бұрын
If you are super lucky and have money to burn, can you sometimes still find the original new old stock zx81 kits.... but its a shame to build those up TBH.
@Clancydaenlightened Жыл бұрын
I bought a zx81 with a bunch of manuals At a hamfest a few years ago, spent $5 usd for all of it cuz the dude was just trying to get rid of it It worked fine too, though the keyboard sucked ass It's the only Sinclair branded zx81 that seems to be ntsc, and also has the back porch issue Motherboard is red silkscreen and has issue one stamped on it All the information I can find refers to the timex branded ones which obviously I don't have I Guess Sinclair may have sold zx81 via mail order before going thru timex in the United States
@ferrumignis Жыл бұрын
@@Clancydaenlightened _"though the keyboard sucked ass"_ Sounds like it was in factory fresh condition then. Lots of companies where selling improved keyboards for the ZX81 back in it's heyday because it was so terrible.
@Clancydaenlightened Жыл бұрын
@@ferrumignis yea it was pretty much like new, didn't even look like he used it much...
@martindejong3974 Жыл бұрын
@@Clancydaenlightened You can just built my keyboard PCB, with real keys behind a plastic/paper overlay. Just remove the two molex 5 and 8-pole keyboard connectors and replace them with angled pinheaders, then just use dupont cables to connect them to my keyboard PCB. Just cut the dupont to 10cm, and strip the cutt off end and solder that end directly into the PCB.
@AK-vx4dy Жыл бұрын
As i rember (not pesonally) ZX-80 has discrete small chips instead of ULA nad was sold as a kit... Anyway ZX-81 was my frist *my own* computer (sigh)... circa 1988... i have one in not orginal case and "normal" keyobard and one pristine.... Many hours, days and months... manually assembling to machine code... dissasembling ROM.... and other nasty things ;)
@tetraquark2402 Жыл бұрын
I built mine back in the day because I was poor. Because you used a bigger eprom you could of added useful lookup tables and routines instead of repeating the zx81 rom image 4 times. Not sure how difficult it would be to allow the system to see it though
@iNimbleSloth Жыл бұрын
Building is part of the fun imo
@iNimbleSloth Жыл бұрын
There are some jumpers on the board, but more like "cut track " or "solder bridge" style to access the different memory banks. I suppose it could be modded with wire soldered to these and switch on the rear of the case through.
@martindejong3974 Жыл бұрын
@@iNimbleSloth yeah some of the builders of my clones added switches to the back so they could select one of the four copies in a 27C256. They asked for support to do that, so I did. But note that the design supports using a 16K ROM, so you can add software for the future extra 8K of firmware to support my coming expansion board with PSG sound, and an SD-card reader. The extra firmware support a menu driven sd-card support.
@5nowChain5 Жыл бұрын
isn't it supposed to be a red sticker on the UV window on the eprom?
@martindejong3974 Жыл бұрын
The color of the sticker isn't relevant, most often the stickers used had a silvery metallic top, so they were even more opaque for UV light.
@iNimbleSloth Жыл бұрын
I've yet to open a machine with a red sticker. So long as it blocks UV light it's all good.
@DiyintheGhetto Жыл бұрын
My question is. Where did you get the part from?
@iNimbleSloth Жыл бұрын
Gerbers for the PCB and a bill of materials including links to two suppliers are all in the designers GitHub page github.com/mahjongg2/ZX81plus38. I recommend uploading the Ferber files to PCBWay for the PCB as they did a great job for me. Good luck with your build!
@DiyintheGhetto Жыл бұрын
@@iNimbleSloth the question was really for the parts list. What parts are needed?
@iNimbleSloth Жыл бұрын
They are all listed in the bill of materials list in the GitHub link above. The document opens in Excel of Open/Libre Office.