[0:00] I’ve made something really cool it’s a complete ESP32 ZX Spectrum emulator. Now in the next version

[0:07] the display will be integrated with the PCB. I did place an FPC connector on the board but

[0:13] it’s only compatible with the tiny displays I was using for the TV project. I have got some

[0:18] bigger displays on order but displays are really a pain in the backside. So, I’m going to use the

[0:24] bigger screen connected via jumper wires for this video. As you can see we can play games.
[0:37] Manic Miner certainly brings back some memories and it seems that I still have

[0:41] quite a lot of muscle memory from all those years ago and we can even program in basic
[1:05] I’m sure a few of you remember going into computer shops and getting the machines to print their

[1:09] names or possibly something more rude on their screen. It’s really nice and I know people are

[1:14] going to want one of these. It’s not quite ready for production yet this is very much at the proof

[1:19] of concept stage of things but I have set up a melee list for you to register your interest.
[1:24] If there’s enough people wanting one I’ll set up a production run and put it on sale. There are a

[1:29] few things things that need to be worked out so despite this saying v1.0 is very much more like

[1:35] V 0.0. In good old Sir Clive Sinclair fashion I’m going to aim for a pretty reasonable price point
[1:42] I want a computer that we can sell for the magic sum of £99. The nice thing about this design is that the

[1:48] keyboard is all part of the PCB. So in theory it should be pretty simple to manufacture . Now why did

[1:55] I even build this? Well I got a spectrum Emulator working on my ESP 32 TV board a while back and I

[2:02] was just going to do a video on that but then I heard about the new full color silk screen

[2:07] printing that’s available from PCB way and I just had to try it. The Spectrum keyboard to go with the

[2:12] emulator seemed like a nice colorful thing to try and do and it has come out amazingly well

[2:18] the boys and girls at PCB way have really done an incredible job. It’s easy to underestimate just how

[2:24] cool this is. This is not just a simple printing job. The ink shoes need to be stable and keep their

[2:29] color at high temperatures used in the Reflow ovens and all the follow-up processing stages

[2:34] It’s pretty impressive that it works at all. So what’s on the actual PCB the brains of the

[2:40] operation are the good old ESP32S3 this really simplifies things as it can be directly connected

[2:47] to the USB we don’t need any extra ICs what’s really cool with this design is that we’re able

[2:53] to get all 40 Keys feeding into just one ESP32S3 I’ve done this by multiplexing the keys in

[2:59] in a similar way to how the original Spectrum keyboard worked this is possible because the

[3:04] S3 has 14 touch pins for the 40 keys on this keyboard we need 13 of those pins there are

[3:11] eight rows each with five columns we can detect each individual key by checking which column

[3:16] and which row is being touched simultaneously it does work really well and it’s really responsive

[3:22] I would say that it’s just as good as the old dead flesh and membrain keyboards on the old Spectrum
[3:34] and it’s much less likely to wear out there is however a small tradeoff that I’m going to fix

[3:39] in the next version of the board I’ll come back to that later all the games

[3:43] are stored on an SD card I’ve got over 1200 games on this card and they take

[3:47] up around 65 megabytes it’s really easy to forget just how small 48k is there’s a

[3:54] small speaker I’ve gone very classic for the sound output it’s a simple speaker driven by

[4:00] transistor one bit sound just as Sir Clive originally intended the results are surprisingly good
[4:22] it is incredible what can be done with one bit sound there is

[4:25] a great video I found recently that does a deep dive on this definitely worth a watch

[4:30] I’ve also added an earphone jack so you can plug an external speaker in it sounds pretty good
[4:50] there’s a battery charger on board so you could have your very own portable ZX Spectrum

[4:55] perfect for working in your local coffee shop though I do wonder if we’re going to need a mute

[5:00] button displays are something that I’ll sort out in the next prototype there is an FPC connector

[5:05] for the tiny display that I’m using for the ESP32-TV project but as you saw this is way too small

[5:11] for real use I’ve got a bunch of 3.2 inch displays on order from AliExpress that I’ll try out in the

[5:17] next version one frustrating thing with displays is that although most of them can be driven over

[5:23] standard 4 wire SPI the pinouts on the FPC ribbon cables are all completely random I’ve got some

[5:29] of 10 pins 18 pins and even 40 pins it’s completely Bonkers for a production run

[5:36] I’ll need to select a supplier and commit to whatever pin out they use I will still break

[5:41] out the display via a header though so we can plug in other displays if needed as mentioned

[5:46] earlier there are some trade-offs with the keyboard you may have noticed when I was

[5:50] typing in the basic program earlier that for symbol shift I tap the symbol she here first

[5:55] and then the character that I wanted I’m using a touch matrix for my keyboard and with the approach

[6:01] I currently have this means that only certain combinations of keys can work in the original

[6:06] Spectrum keyboard they prevented this by using some ders on the address lines now this is not

[6:12] really possible with a touch matrix but I do have some ideas on how to fix this that I’ll

[6:16] be trying out in the next revision to be honest it’s not a big limitation but it does mean that

[6:21] some games can have some surprising behavior as combinations of keys can trigger other keys you can see

[6:27] this when playing Elite if I try and pitch up and roll right it thinks that symbol shift is

[6:32] being pushed and I slow down to zero speed so the next version of the board should hopefully fix

[6:38] this so stay tuned for updates of course with the first version of the PCB there are some mistakes

[6:44] and I had a couple of big ones the first ER was that somehow despite copying the design

[6:49] from my tiny TV board I completely messed up the ESD protection chip so I’ve had to remove this

[6:55] and put some jumper wires in I may just remove this IC completely cuz I’m not really sure it’s

[7:00] needed the second error was on the speaker driver during some over enthusiastic bomb optimization I

[7:07] accidentally placed a p Channel mosfet instead of an N channel one so that didn’t work at all this

[7:12] was easily fixed but I didn’t have the right size one fortunately my bodge is barely noticeable so

[7:18] I’ve got a few kinks to work out before this can go on sale make sure to register your interest

[7:23] if you’d like one over the next few weeks I’ll be working on the next prototype and I’ll keep

[7:28] you all posted as I think this is is really cool I’ll also do a follow-up video soon with a lot

[7:33] more technical details as I know some of you will be keen to understand how it works under the hood