Interface projects would be really interesting James. I have a few Spectrum's myself (ten I think) ranging from 16K to +3A. Most were bought as a job lot and all with various faults. All are now fully working. Retroleum is a good online shop for spares if anyone is interested.
Brings back happy memories - I started off with the "dead flesh" keyboard and we upgraded to a plus after I argued that it had a "proper keyboard" which meant my dad could do his typing on it...
Good stuff! We actually started with the rubber keyboard version and got the upgrade, that was pretty quick though so I never got used to the rubber one.
I actually thought this would be "Noel's Retro Lab" but instead it is more Sharman!! A Nice surprise to be sure. Noel's is worth a watch if you like 8-bit computers. I think he makes the best repair and troubleshooting videos on the internet.
@@weirdboyjim The surprise was just that I was expecting Noel. This is a pleasant diversion. I was a c64 guy so I am pretty lost in the z80 world. But the composite mod you did is very common these days.
I had a ZX Spectrum 48k and when I got fed-up with competing with the family for TV-time to use it, I bought a PAL monitor and took the Spectrum to an electronics repair shop and asked them to bypass the modulator and give me the composite out. That was the start of freedom and a very nostalgic time that was the beginning of so many things for me.
@@weirdboyjim Of course then I wanted to print things, bought a printer and parallel cable, but found out that I still needed other things. The sales guy told me later that I needed a Centronix interface, which would connect to the expansion connector and expand it further so you could still add other expansion devices. It had a parallel connector for the printer, and that opened up another avenue to me.
This takes me back. I built a DIY RAM + UART board for my ZX80, internal 16k RAM expansion for my ZX81 (in the space under the keyboard), and on my Spectrum I expanded RAM to 80K (all internal, bank switched) and added a 6-channel sound (dual AY-3-8910) and UART I/O card. The UARTs were old Signetics 2651 devices and were used to talk to an old ICL Termiprinter (weighed a ton, and topped out at about 600 baud I think). Fun days. Sadly I have none of the computers and only the last of the external boards sitting around. It will be interesting to see what you come up with.
I have the same processor in my early history, in a different box (TRS-80). Learned much about assembly language and digital interfacing then - many modifications and additions made to the unit - immense nostalgia here. Very happy you found one, and looking forward to your explorations. A bit misty-eyed here.
Ahh the old "Trash-80", although I only know that nickname for it from the quote "What you seek lies hidden in the trash on the deepest level of Daggorath"
@@weirdboyjim It endured much modification and extension - so the nickname never made sense to me. Perhaps because it was strictly black and white video? Considering how early it came along, I forgave it that.
Congrats on the Spectrum. I went the route of waiting for a Spectrum Next. I'd prefer to get a retro unit but I have way too many battles to fight to add a potential refurb/repair to my stack. Kudos on Manic Miner, I can't count the hours I spent playing it and Jet Set Willy 😇
Thanks Vince! The one I remember playing to death was JetPac! I'll have to try and get a copy of that. Fortunately the magic of video editing hid the many fail attempts at completing the first level.
Great video (still watching, but couldn't help giving first like and comment). After my ZX81 I got a 16K ZX Spectrum, later upgraded to 48K. They gave me many years of fun and the basis of my career... Expansion modules were often compatible, even got some for the ZX81 that fitted on the spectrum. Those extra pins were probably not required by that module. (Now have to watch the rest. See you later...) Edit: a big thank you for the trip down memory lane. Congratulations on your purchase and I'm actually looking forward to any follow-ups!
Thanks Maxint! I'm curious to take a look at the difference between the zx81 and spectrum expansion ports, that they have some weird level of compatibility is interesting.
I really love your video's and now that you are going into retro computers - yeah !!!! Even thou I did not have ZX Spectrum "any model", or a Commodore C64 back then - I did buy an Amstrad CPC-6128 in 1984. And was going a completely different way than all my friends. Well.. I did not spend my time playing games but learned to program both Basic and Z80 which also had a big influence of what I have been working with for the past 32 years. Gee, I am getting "old". Looking forward to see you revive that old ZX Spectrum+
you can't beat a little retro interfacing, I did this a lot for the cbm pet and early pc's to control test equipment. thanks again for bringing back memories 😊
@6:22 I've got modern flat panel TVs with UHF/VHF tuners. Many countries still use analogue TV broadcasts and so the industry continues to cater for them. Good job btw.
My first computer was the standard rubber keys Spectrum 48K but it was not a family one, it was my own that I saved paper round money for. I was later gifted a Spectrum 128K, the one in the plus case and the heat sink coming out the side. I still have both in my possession though the 48K is a bit roughed up with the faceplate glue failing.
My Spectrum+ was actually an upgrades rubber key device. The board inside was the same, the family bought a 2nd hand rubber key spectrum with a slightly dodgy keyboard and the upgrade kit.
@@weirdboyjim That's pretty much what the Spectrum+ was anyway; a case upgrade. If the board had been redesigned for the case then the reset button would not have been connected via wires across the whole board.
That was the computer I wrote my first program on. Not my first computer though, which was the brown Commodore 64 in the year 1985 used almost exclusively for gaming. Nice score!
Brill:-) One of the oddities of the zx range was the extemely limited release of aftermarket midi interfaces. The 128k could do midi out with the appropriate cable, midi in was not so easy and I suspect it was down to lack of memory that nobody bothered developing it. The Atari st was already well established, so that too. Still it would have been nice to use the speccy with a midi synth.
I started with a zx81, with 16k expansion, which was gifted from an uncle that upgraded. Later we got the zx spectrum rubber key, one of which I still have. We eventually had an interface for it that had two joystick ports and a ton cartridge slot, which I don't recall ever finding any cartridges for. It died in some hardware hacking and I lost interest in home computing until my late teens when I got an Amiga. Then I was hooked again. Forever this time lol
I used a ZX81 at school a bunch before we got the Spectrum, good old ram pack wobble! What you are describing is the ZX Interface 2, I've actually ordered one of those of Ebay as I want to take a look at that cartridge port.
I don't remember it having a lot of components. Maybe a single IC and that was for the ports I think. All the data and address lines ran straight to the cartridge socket.
A very nice change of pace actually. I love the retro repair stuff! I for one would love to see more expansion connector experiments. Perhaps even a means to communicate with the CPU project.
@@weirdboyjim Perhaps allow your CPU project to use the z-80 as a co-processor? The speccy have all the signals you would need at that edge connector. Just a thought.
Oh, a spectrum, how...nice *gently strokes BBC with co-processor,RGB monitor, winchesters and dual floppies*. heheh, no seriously , congrats on getting your hands on a childhood dream. *one owner, not for sale.
Well someone was borne with a silicon spoon in their mouth! My best friend growing up had the bbc when I had the spectrum, he made sure I was well aware of it’s virtues.
@@weirdboyjim Yes but you made so much more of the silicon investment, I built an 8 bit sound sampler for the BBC user port somewhere back in 87 and didn't touch a soldering iron for 40 years, now I dabble in arduinos, and you built THIS?!?!
My first computer was a ZX81, but got a speccy soon after and had it for years. I bought a number of add-ons over the years, but the best was a MGT disk drive, which transformed the machine. I wanted to get a Sam Coupe but it took so long to come out I got an Atari ST instead.
My school had a ZX81 I was able to mess around on before we got the spectrum. I don't think I knew about the MGT when I was young or I most certainly would have wanted one of those!
I had a Jupiter Ace.... sort of "second cousin" to the Spectrum.... it would be lovely (if only for a few hours of nostalgia) to get my hands on one again.... or my flat mate's Oric Atmos.
@@weirdboyjim designed by the same bloke as the Spectrum not long later.... sort of like a black and white 3K spectrum with FORTH instead of BASIC. No ULA, so it was full of TTL and had to cut back on memory to cut costs with a higher chip count.
@@weirdboyjim Honestly I would just go with something less actually "microdrivey" and use the port. The protocol seems well understood and there are already plugin replacement devices for the beleaguered little drives (I think I have a couple of the tapes, not sure about other devices, have to look what is in the crate) thus the creation of your own tool for general misuse seems not too far fetched. For my part I would like to get it working as a browser I think for some very basic web retrieval tasks. The thought of the QL client being in a weblog somewhere makes me smile inside.
Excellent! Get that expansion port investigated, I had great fun making a programmer for an old 256b PROM, I used the interface of a C64 to operate it.
On the video out connector, you can see that the resistor broke of - on the socket, it's a clear dry separation. Not surprising on those connectors. I did those mods myself as a kid :)
@@weirdboyjim I saw this a lot in the '80s. Kids (like me) jammed connectors in way too hard, and those modulators were designed for essentially a single insert and then leave in. But we moved them from room to room daily. I see the same issue today with Micro USB connectors :)
I rember the thrill and shock when i came across black box in one of classroom cabinets... It's was about 1987 and school was in tiny city in poor eastern european country... To this point i saw this only in magazines... or tv... I could not let it stay closed in cabinet. First i send anonymous letter to principal, then another one signed... I was called but insted of punishment I got a news but mixed. It was planned to start school interest group... but only for two oldest school years... i was devastated, vision of 2 years of waiting was depressing. But fortune not leave me entirely, i asked teacher if i could join anyway, he asked one question "what programing means?" and i passed the test. Finally for the whole group there was two of ten or tweleve wich wanted learn BASIC, rest waited only to end when they could play some games. This was milestone or fundingstone in my long story with computers... for my first own machine i had to wait 4 years more...
This is going to be interesting! I'm of the same era, but was as much into the hardware as the software. Although I never had a joystick interface... So I'm looking forward to seeing what goodies you connect to the back of the Speccy.
Every time I buy a ZX Spectrum Plus I do it for the case. The case is for the HARLEQUIN 128K REV 2D board. For me the ZX Spectrum 48K must be the 48K. Not a case such as the Toastrack which I also have. If it’s your first computer I can respected that which my first is the Commodore 64 Breadbin. Which is still have and working every day on since 1984. My first ZX Spectrum is the Toastrack 1986. Which is also still have and must be repaired in the near future. Like the new ZX Spectrum 48K cases which I hope come this week. Maybe I would buy the ZX Spectrum Next. Normally I do stuff with the AMIGA 500, AMIGA 1200 and the Vampire V4 Standalone but now I liked the ZX Spectrum more. Maybe the feeling from the past is stronger than I expected. Use also the ZX-HD, DivMMC Enjoy! Pro One on it and the ZX DIAG Cart. There are many things you can do with the ZX Spectrum such as the SpectraNET.
For me this plus IS the spectrum, the rubber key variety wasn’t one I had much time on. I didn’t care about the keyboard so much but a reset button was valuable to someone doing early experiments with coding.
I had the rubber keyboard spectrum 48k. Manic Miner was a class game. The speed king joystick was robust. As I broke a quick shot 2 in less than 3 days
@@weirdboyjim yes it is. Daily Thompson’s decathlon killed the qiuckshot 2. As it only switches for up,down, left and right that best description was thin sprung steel not micro switches like the speed king joystick had.
The resistor broken in the RF modulator is a common fault. As it started by the wiggling of the RF mod cable and would fatigue the joints on the resistor.
just found your channel loving the vids my first computer was a ZX 81 with a 16K ram pack would love to find it its sum were in the house just thinking my phone has more power than that old thing LOL still love to mess around with it thou :D
@@weirdboyjim o yes the wobble bin typing code in get like to the 1000 line and nock the table ops gone you ever try the frozen peas on the ram pack to keep it cool never try it my self :) LOL
Nice! I also had a ZX Spectrum in the day, the one with the rubber keys. It got lost somehow and about ten years ago or so I bought another. Unfortunately I never had time to really dive into it again and it is still stored in my attic right now. I'm very curious what you will do with your Plus and may take inspiration from it. I've had vague ideas about using it to drive some sort of robot or kinetic art thing. The kind of project that nowadays one would probably use an Arduino for.
The circuit board for the Spectrum+ is exactly the same as for the rubber key version, it was just a different case and keyboard. Ours was actually an upgrade hit from the a rubber key version.
@@weirdboyjim Yes I'm aware that it is essentially the same computer. Which is why I can't wait to see what you're going to do with it. Show us the way, oh exalted guru ;-) Perhaps it's interesting to mention that in the 80s I knew someone who used a Spectrum to control a model railroad. Personally if I had to design an interface for it, I think I would like to make sure that all the signals went through optocouplers (e.g. LTV-8x7 series) to keep the computer isolated from whatever current that wants to destroy it. Probably not necessary if it's just a ROM or RAM extension, that is, something without external power.
I need to get my Spectrum going again. It's still the one I got second-hand when I was 11 or 12, no idea how much (or little) is going to be wrong with it, apart from the membrane where some of the bits did tear off
Hmm, I'll try and get CAT next time I have it powered up and report back. The weird input method was actually a space and code saving measure, clever for the day but annoying these days once you are used to something more.
I suspect the popularity of the Spectrum in the UK was due to a couple of reasons, lower price than the Commodore 64 and the absence of MSX computers. The Speccy's popularity certainly wasn't due to its lousy sound capability nor its graphics capability that could only be exceeded in crudeness by something like the Mattel Aquarius. But despite those limitations, game programmers often did a decent job porting games to it as well as writing games original or exclusive to the Spectrum.
Yeah, the humble Specy dropped under £100 very early in it's production which I think was a massive factor in being seen as affordable for the average family.
So, what's the proper value for the composite mod capacitor? And, is it essential to fit in one to just check if the machine works, albeit maybe with bad quality picture?
This one was 100uf which was a value used by a number of guides. As such I'm not comfortable enough in my knowledge of the composite signal and related analogue electronics enough to declare it the one true value. It's there to block DC so a bit higher should be fine, go too low and it will start to round out part of the signal and you'll loose resolution.
You said no UHF on modern TV's... Quick look on a TV shop assist website tells me most 80 inch QD Oled stuff still has it. 1200 models with analog in available!. I don't like big TV's, so I've a 32 inch Bravia from 2010, and those as well do perfect playback of Speccy UHF signals. You won't need a CRT for this for sure.
Do you know verilog? If not, you should try it, you would learn it at an alarming rate if you already know this much digital logic stuff. I'd love to see what you do with FPGAs. I am considering getting one of those M.2 FPGA prototyping devices and playing with making a PCIe agent that I can access from a driver and do DMA and post IRQ messages. It's the modern version of the idea of making something to plug into the expansion port.
We touched on Verilog and Vhdl at university but I don't remember any of it apart from some outline concepts. I actually plan on doing some fpga stuff in the future, but not until this current build is fully finished.
I`ve done loads of fixes to mine and now I have to change all the upper ram. Not looking forward to it. I`ve already fitted new 9 volt socket, regulator, caps, video mod, mic and ear socket, keyboard sockets, keyboard membrane, speaker and one upper ram chip. I hope I don`t ruin the board doing the ram change.
Interesting. I like the way this exposes the way basic programs are stored internally. Of course If you have a line editor that is tokenizing then you introduce the possibility of typos.
@@weirdboyjim I seem to recall fantasising about being able to type whatever I wanted back in the day, now spoiled by syntax highlighting, intellisense and network files it hardly seems to matter.
Every modern flat-screen TV I've had, has had analogue and digital options for tuning. Try it. See if you can analogue-tune into it on channel 36. Should work fine. The world's already full of dodgy analogue mods where someone just cut the cable at the modulator, leaving a signal that's at the wrong voltage and unknown impedance. You're not losing anything running it through RF, some might say there's even a benefit to the slightly rounded softened pixels. Don't try programming it though, on a proper knackered old 1970s TV, it'll send you short sighted! Actually a modern LCD TV will probably give a sharper signal, lock on to it better.
I have 2 tv's in the house, one doesn't seem to have any sign of an analogue tuner and the other is wall mounted upstairs. To be honest though, a spectrum on a wide screen display would feel kind of wrong.
@@weirdboyjim Your TVs show Freeview, right? Through a normal aerial? It's the same connector. Usually when you setup your TV there's a menu that searches for all the channels. Just before, there's an option for analogue or digital. I imagine the analogue is going to be pretty quiet these days but it should pick up a Speccy fine. AFAIK all TVs have this option so all should still work with the good old stuff. As for the wide screen, doesn't your remote have an option to switch between 16:9 and 4:9 ? Or do it automatically? They used to.
That was my first thought, but under load it only dropped slightly (I didn't include that in the final video cut). They actually just put out notably more than 9v for the regulator to drop down.
Yeah, That second issue I had was "solved" by pulling the ribbon back out a fraction of a millimeter. Tempted to do some kind of custom keyboard for it actually.
Expansion bus shouldn't be that hard, just a matter of address decoding and data bus latching. Good luck, and if you have any questions, come see us on Engineering Stack Exchange or Retro Computing Stack Exchange!!!!
@@weirdboyjim LOL, my apologies. It seems at the late hour I made the post I had misremembered your past experience. Indeed, the interface should be a "walk in the park" for you!
You know, you should never turn on old power supplies without a load connected, some are not designed to handle a no load fault and stress internal components beyond spec.
Nah, Other supplies are worth caution but the spectrum power supplies were very tolerant. If I had seen weird behavior from it of any kind I would have discarded it for a new one.
The ZX interface 1 added a serial port, would have been nice to have by default though. Let's not forget that the building for minimal price was what made this device so common, had it been more expensive it might not have had the same level of impact.
I once recorded an ebay unboxing for a minute until I realized it wasn't the item I thought it was (It was a replacement part for my vacuum cleaner). I spared the channel that short video.
