The TZXDuino Compact v1.01 PCBs arrived today from Hackvana.com I have built one and tested it successfully, so the design files are on the AVR Projects page. Feel free to use the Gerbers with your favourite fabricator (Hackvana are good!). Alternatively, you might like to modify the design to suit your own requirements so I have included the KiCad files and a schematic along with the latest (v1.7b at the time of publishing) arduino code.
For some TZX/TAP files, the output seems a little weak but in conversation with Duncan Edwards, one of the designers of the original device, he told me that later Spectrums do suffer from a less sensitive input. I will look into updating the design with a small amplifier to alleviate this issue. It has also come to my attention that I’m using the wrong display. The code specifies a 128×32 OLED and I have used a 128×64 OLED version. All this does is stretch the characters though so it’s OK to do so. The connections are the same. Admittedly, it does look slightly better in smaller text but the display is rotated 90 degrees. Choose which one you feel works best for your application.
Meanwhile, the composite mod suggested by Andrew Gostling wouldn’t drive the Dell UltraSharp 2007FP monitor. It seems that this particular monitor is really picky with it’s input signal. It also fails to work with my ZX Uno. I have since started using an alternative Dell E173FPf monitor along with a ZX-HD interface, driving a HDMI to VGA adaptor. The ‘2007FP will be pressed into service elsewhere!
I have a few other Spectrum related projects on the go. I have formalised Andrew Gostlings Composite Mod along with two other popular options and designed a PCB to replace the original 48K/128K/+2 modulator internals.
This I have yet to prove, but once I have had PCBs made and tested them I’ll be publishing the design files on here under Non-AVR Projects.
Another Spectrum related project is a Floppy Drive adaptor board for the Spectrum +3 It is meant to give the facility of easily making a connection cable up from an old PC style floppy cable and giving the facilites of both setting the drive as Drive A or B and also using Side 1 or 2. I have had no end of trouble with this one and development continues.
Yet a another project is an NMI interface, initially for 48K Spectrums. This will hopefully allow interruption of any program running on the Spectrum and an alternative ROM to be paged in, similar to the Multiface except you can use a custom ROM. I’m hoping to be able to run the Multiface machine code monitor Genie and maybe the Specmate snapshot devices ROM Code.