Tales from four decades in the Sinclair aftermarket: Parts, upgrades and party tricks

RWAP Software owner Rich Mellor talks ZX81 sound cards and linking USB printers to parallel ports

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Liam Proven (LP): Hello again, and welcome back to The Register Retro Tech Week. I'm Liam Proven, the open source and Linux correspondent for The Reg, and with me today is Rich Mellor of RWAP Ltd and the Retro-Printer. Rich, thank you very much for joining us.

Rich Mellor (RM): Thank you. Nice to meet you.

LP: Could you could you introduce yourself and your company or companies?

RM: Yes. It's a range of companies. I actually started using the word RWAP as a brand in the very early '80s. I was using this on school essays and actually any piece of programs – I learned to program on the ZX81 at the time and then moved on to the Sinclair QL, which actually became pretty much my love.

LP: So you skipped the Spectrum?

RM: Yeah, never took to the Spectrum. Never played a game. That was my brother's bag. Officially, RWAP software was launched as a business in 1986 and has been running ever since. But it was there to set up a platform for me writing articles for QL World, as it was called in those days and testing software mainly from CGH Services. I did a lot of software in the early days for the Sinclair QL and it helped pay the bills as I went through university.

LP: Yeah, I know that feeling and I was at university myself around then.

RM: I came out of university with more money than I went in with.

LP: Wow, well done! I came out with an overdraft and had to save up for about a year before I managed to buy myself an Acorn Archimedes. And I think I bought a motorbike first actually – I fell off a lot, but I'm still here.

So, RWAP – you offer spares for quite a few different Sinclair machines – the ZX81, the Spectrum, the QL, and the Cambridge computer Z88. So you said that you went from the ZX81 straight to the Spectrum – which of those maybe is your is your favorite – or is it the 88?

RM: Well, the Sinclair QL is my favorite. Mainly because I learned a lot about programming on it. It had a lot of modern techniques writing procedures and functions which nowadays, classes in when you're writing software, and it could offer recursion, it could offer you known passing parameters by reference, and all these sorts of wonderful things which made programming so much easier.

And then I taught myself 68,000 Assembly language on it, and I found that a lot easier than what I'd been doing which was trying to learn Z80 programming on the ZX81. Mainly because you don't have to worry about anything like memory paging or even running out of memory on the QL because you've got 128k, which seemed a huge amount at the time.

LP: Who could ever fill that much?

RM: Yeah, you could actually quite easily write a program in SuperBASIC, find which were the time critical bits and rewrite those in machine code just as a new keyword. It's a fast way of developing software.

LP: I do have a QL but I got it, you know, long after the event, unfortunately for me, but so I never really got to know much about SuperBASIC, I haven't used it very much. It does seem to me it's very strange that this you know, quite late era, very rich, sophisticated BASIC, there's no open source version or clone or reimplementation of it that I know of.

You know you can run Spectrum BASIC on a modern computer, you can run Commodore 64 – their terrible, terrible BASIC, but SuperBASIC, which I guess it was probably hand-coded in Assembly, but the code is out there, you know, nobody's got it modernized yet. It's kind of a shame. So which, though, maybe for your business or for RWAP, which one is the big, the big revenue earner, if I may ask? I would guess the Sinclair?

RM: From the Sinclair machines? It's actually the ZX81. Now ZX81 was a very quiet, backwater computer when I started looking around the internet, in probably about 2005, something like that. There was hardly any discussion of it on the forums. There was nothing on anything like Facebook or... and I thought "Well, I wonder. If I just set up a discussion forum specifically for the ZX81, where it could go?"

So I created what's now known as Sinclair ZX World. And like, we've got a few members that hit about 50-60 within three months. And people were all saying, "Oh, we can't use our ZX81, because it's only got a keyboard membrane. It's not working any longer. So decided, I took the plunge, invested money in getting some membranes made for the ZX81, expecting to sell maybe half of them because I had to get 250. I have now sold nearly 2,000 – and I still get orders every day and the forum's reinvigorating the market completely. It encouraged people to write new software, it encouraged the development of the ZXPand interface, and some ZX81 clones and things.

LP: So yeah, the first personally owned computer I ever touched was a ZX81. My uncle Tom bought it for himself, you know, that year... and could not work it at all. And we, my mom and dad and I, visited my aunt and my uncle in West Kirby, on the Wirral. And he showed me his new toy and I was able to get it working for him and show him how to enter basic programs from the manual and save them onto tape.

Sadly, my poor old Uncle Tom died in 2003. My auntie Val died just last year. She remarried, bless her, at 85 – good luck to her – and had a very happy last few years.

And I'm in touch with her husband, and he says he's seen the ZX81 in a box somewhere. And when he can find it, I can have it. I really would love to get not just any of them, but my uncle's one – that would be lovely. So tell me what exactly does the ZXPand do? Because the ZX81 is pretty limited. What does it add? Apart from the famous RAM pack... with no wobble?

RM: I mean the ZXPand still does offer RAM pack wobble, if you like it! It was the brainchild of a guy called Charlie Robson, who decided he wanted a simple method of adding an SD card onto the ZX81, for loading and saving games quickly, so that when your RAM pack wobble happens, you can reload the game quite quickly or immediately.

Whereas it adds 32k RAM and the new update adds AY sound and a joystick port and implemented a fairly easy method of adding joystick support into some of the games. But originally it was going to just be a hobby project for Charlie. I pushed him to make it into a commercial product. And we did sell it together for quite a few years. And then as other priorities came along the lines, Charlie decided, you know, I need to slow down I can only make maybe 10 every now and then. Some of those, you know, it would list on my site and they'd be sold within two minutes. Because people would just cry out for them.

LP: I can't think of anything else like it, is there?

RM: There isn't, no, not really. Certainly not for its simplicity. There is one other interface, I can't remember the name of it, where you can use a USB stick and of course there's things like the TZXDuino, which acts as a tape player.

LP: Yes, very interesting.

RM: But yeah, Charlie's now agreed with a company in Slovakia called PCBNow to actually start producing the ZXPand in bigger numbers again. Although they can't keep up with demand either at the moment, it's surprising just how many of those are probably out there on the market.

LP: Oh, yeah. I mean, I think you know, that the Spectrum was the famous one that kind of grabbed the headlines, but the ZX81 I believe was the most profitable thing Sinclair Research ever made. You know, they sold huge numbers of them and on a very nice profit margin as well. And I really hope nobody's running a nuclear power station on one, as they claimed in the ad.

And so you also support the Z88, which is a lighter Sinclair computer after he'd sold the Sinclair Research name to Amstrad. So, you know, how, for example, do you get spare parts and things for a Z88 in 2023, when it's a 35 year old machine?

RM: Well, the Z88 is an interesting machine. The main problem you have is that it loads programs from EPROM cards that basically go into slots and there are custom built case on them, but people have remade those and you can actually buy an integral RAM and SD card, no sorry, RAM and and EPROM card. It's got Flash EPROM in it. It fits into one of those slots, and you get 512k RAM, 512k Flash EPROM, and you can quite easily download software from a PC. The beauty of the Z88 is that it was completely silent. The main focus I've come across is from people who used it for doing family research because they could go into a library, they could go into a church, and tap away quite happily without anybody knowing.

LP: Yeah, yeah.

RM: And they were quite robust as well. I did sell one a few years ago to a journalist that was going around Africa on a motorbike. Well he was concerned if you took a laptop, the jiggling and the vibration from the motorbike would soon break the screen away from the keyboard. Where would you get electricity to charge it? You know, you can't get a replacement battery. A Z88 – 4 AA batteries? Most villages probably in Africa have those. And off you go.

LP: I have one. I wrote a piece for The Reg more than a decade ago when I was a freelancer, saying, I think I called it something like "Where are all the decent handheld scribbling tools?"

But I bought a Z88 and I bought an Amstrad NC 200. Both of which at that point cost me about a tenner and are now worth quite a lot more. So I mean, I find it kind of sad that there isn't like some, I don't know, all-in-one Raspberry Pi case or something in that form factor, because I think it was a good one, but maybe if I want that I'm gonna have to make it.

And you've got a new bit of shiny in recent years, which I only discovered quite recently: the Retro-Printer. What's that for? What does it do? It's a Raspberry Pi-based module, but it's got a very specific... it fixes a major problem that people have these days. Can you tell us more?

RM: Yeah, it basically is a piece of hardware that slots onto the top of a Raspberry Pi. And it sounds simple. It just allows you to connect a parallel port to the Raspberry Pi and intercept any data being sent out, which was traditionally going out to a dot matrix printer, or early inkjets.

I came up with the idea in 2000. I was working on the baggage handling line at Heathrow. And we needed to print out simple data saying "this is what baggage has come through, this is how we're tracking it through the system." And when we went off the end of the system, proof of the same baggage tag. And we searched high and low and we only could find an old Epson dot matrix printer, which cost about £500 at the time.

LP: Oh yeah?

RM: Yeah, it's still the same price it was in the 1980s.

And although it was brand new, it was still fairly unreliable because it relies on you know your paper that's got the holes down the side, so those rip off, and the paper gets jammed and twisted, and – you know – you're still stuck on that. But we couldn't put in a modern printer at all, because the industrial equipment we've got, we've only got a parallel port. And also, there was nobody there to go and put more paper in the machine.

LP: Yes.

RM: There's not a lot you could do, you needed continuous paper. And I just thought: well actually if you could have a little device that captured that data coming out of a parallel port, it could store it electronically – either logging it or PDFs, and then that could be interrogated remotely, and it gives them the same proof as actually a printed sheet of paper. They could always print up the PDFs if they wanted to. Unfortunately, the cost of doing something like that would have been horrendous.

There are some devices that were designed around that sort of time and onwards and are still sold in the US. And the price has come down recently to about $400. And that's without any software!

So, you know, you can capture the data. But what do you do with it? Very few people know what to do with Epson ESC/P codes and ESC/P 2, and certainly modern printers don't tend to understand it.

And so when the Raspberry Pi came out, it was 2012, so 10 years [or so] ago, I thought, hey, there's an ideal little device. Because it's fairly cheap. Lots of retro computer users were getting them anyway. And so all you needed was some method of getting the data onto it. And then a bit of software written in C, which could act as a printer emulator, and interpret the incoming data, say, "Well, that's an Epson code. Okay, I'll change that out and format that page in PDF."

And then you can print out to a modern printer direct from the Raspberry Pi, the network printer or USB. And so we came up with that with a German developer – he did the hardware locally – and we launched probably about 2018. Unfortunately, there was a bit of a manufacturing problem, in that the manufacturer wired the Centronics pins back to front.

LP: Probably never seen one before.

RM: Yeah, it worked on some computers. We tested it. It worked fine with a QL. It worked fine with an Amiga. But when you put it onto a PC, Raspberry Pi just died. So we ended up having to make some nice little converters which go in-between the cable and the Retro-Printer.

Unfortunately, it's made by hand because you can't get any way of solving 32 connectors that easily, back to back. But then we launched the version for Retro-Printer in 2021. Which was of course an auspicious time, I corrected the issues. But then we had the pandemic and we have supply issues actually getting a Raspberry Pi.

LP: Well, it sounds like a very clever gadget and it clearly fills a need.

RM: Yeah, and it's attracted all sorts of industry to it as well. I was shocked, to be honest, because industry has come to me and said, "Well, I've got this old equipment, I've got a welding machine. We'd love to be able to capture all the data on welds that have been done, so that we can actually sell that data, as proof of what welds were done – say to an aircraft – by what equipment by what person on what day." And then if one of the welds fails, they know who they can sue.

LP: Yeah.

RM: And of course, welding machine, you can put a printer on the outside of it, if you can find a dot matrix printer. There's things like opticians, veterinary suppliers, even flight simulator companies have come over to me, asking for a way of capturing the data.

So we had to expand. We're not just Epson emulators, now. It's emulators for HP, Seiko, IBM, Tandy, a little one called Printronix, and even, we ended up doing an emulator for a Siemens printer. Now Siemens are big industrial controls companies. They make PLCs that control everything from traffic lights up to the Space Shuttle they used to do.

And they had got no idea on how to program their printer anymore because they hadn't produced one since 1990. And that was actually a pharmaceutical company still using this on a production line. And they were about to throw out the £5 million worth production line because they couldn't actually print out what they'd been doing during the day, as proof.

LP: You saved them a lot of money.

RM: So yeah, for Retro-Printer, which costs about 45 quid for the version 3, the coast of a Raspberry Pi, and we provide the software for free download – or we'll sell it on an SD card. You know, it saves them a hell of a lot of money.

LP: Yeah, yeah, that's fantastic. I salute your inventiveness because that you know, it seems like an idea that I'm not gonna say it was obvious, but it's like, you know, I can see a need for this because it was such a widespread standard in the 20th century. It's, it's just basically gone now.

I suspect that we could go on about this for another hour. But I think I've got to draw this to a close now. Thank you very, very much for taking the time to talk to us today. And thank you very much, not only for the interview, but also for the cover for my Microdrive.

And yeah, I am going to take my Z88 with me when I move, and it sounds like I may need from what you're telling me, to seriously investigate putting this thing into, into productive use. Thank you very, very much indeed for your time. And thank you very much for joining us. Cheers.

RM: Thanks very much, Liam.