Using TZXDuino to play UEF tape images

TZXDuino is a cool Arduino project that is basically a standalone hardware cassette audio playback unit for old computers. You hook up an Arduino, a microSD card adapter, an I2C LCD display and 5 buttons. Load a microSD with lots of game dumps, and hook that up to the audio input of your ZX Spectrum or Amstrad. With the buttons and LCD you can scroll through the files on the SD and basically ‘hit Play’.  So it can play the most common ZX Spectrum tape dump formats ; TZX and TAP (plus a few for the ZX80 and ZX81), and CDT format (for the Amstrad) as it’s basically the same as TZX.

It can’t play UEF tape dumps though. UEF is the tape dump format used by the BBC Micro and Acorn Electron. My current way of loading UEF files on my Electron is to use freeuef-alsa  on a linux PC with its audio out hooked up the Electron. Every time the Electron pauses the cassette I have to hit space on the PC, then wait a bit and press Enter to get it going again. It is not ideal.

So basically I’ve been hacking away at the TZXDuino code to add in UEF support. There are a few caveats at the moment
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BBC Micro Model B

I recently bought a BBC Micro Model B. It sold ‘as is’ and I had no idea if it worked. The case was very yellow. It came with a  5 1/4″ drive, cassette player, several books and original versions of Elite on disk and cassette. It did not work, and ended up having a number of faults

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Amiga Kickstart Switcher with no switches

A while back I burnt some 27C160 EPROMs for some of my Amigas. This allows you to have 4 kickstarts in an A500 or A600. Normally you would wire up two switches to the upper address lines of the EPROM to select the 4 images. But I thought there must be some way of selecting the images without needing some switches at the back of the Amiga.

So I’m using an ATTINY85 to drive the two upper address lines of the 27C160 and monitor Ctrl-Amiga-Amiga. You select a different kickstart by changing how long you hold down Ctrl-Amiga-Amiga for.

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Amstrad CPC-464 and broken sound chips

So I was pretty chuffed with setting up my Frankenstrad using just a CPC-464 motherboard and a homebrew keyboard. However, as luck would have it, a few weeks later, the local auction site had a couple of real CPC-464’s for sale … so I bought one.

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So I bought the motherboard out of an Amstrad CPC-464. This was like my Oric Atmos rationalisation . It’s cheaper to just buy the motherboard of some of these old computers, rather than the whole computer (especially when I add in postage from the UK to NZ). And I am more into these old computers for my own curiousity and educational value, rather than just purely ‘collecting them’.  In the case of the Oric, I came up with a Arduino based ‘PS2 keyboard to old-school key matrix’ converter to get around ‘not having a keyboard’.  I was thinking of doing the same for the Amstrad, but I had a nice Cherry keyboard that I was given for free; ie. individual keyswitches and an easy single sided PCB. So I butchered it to turn it into an Amstrad keypad (well most of it).

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SIO2SD with an Atmega328p

So, I have a SIO2Arduino setup hooked up to my Atari 800XL as a virtual floppy drive image thingee. It works pretty well and was really easy to make; one Arduino Uno plus one Arduino SD card adapter plus a few wires. Another popular one is SIO2SD. You can buy prebuilt SIO2SDs  from Lotharek , but like a lot of these devices its ‘just a microcontroller hooked up to an SD card with some buttons, LEDs and maybe a screen. Currently SIO2SD is based on an Atmega32 microcontroller. I had a spare Atmega1284p (like I used in my SD2IEC). It’s a 40 pin AVR chip like the Atmega32 …. so I set off to convert the SIO2SD software to run on the Atmega1284p. However, when I finished I thought I’d see if it would compile for an Atmega328p (as is used in the Arduino Uno). And hey it did compile.

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An Oric with a PS2 keyboard

So I ended up buying an Oric Atmos motherboard on I don’t have an Oric Atmos to repair. I somehow rationalised this as ‘this is cheaper than buying a whole Oric’. Of course a key problem with buying an Oric motherboard is ;

“There is no keyboard”

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The Gonbes GBS-8200 and Arduino Uno

Ages ago I read this shmups post about hooking up a Raspberry Pi to an GBS-8200 to ‘get better control of the Gonbes’. I remember trying it. Had a bunch of problems … kind of got it working .. . and kinda concluded it was too much hassle, but had enormous potential. To me the Gonbes is ‘90% of the way there’ for doing the 15KHz/50Hz RGB modes the Amigas and Atari St put out. Sure it connects and shows an image, but like a lot of people I get random noise in the image and there’s some weird artifacting that goes on …. but its really good value for money. The shmups project added in some ‘non scaled modes’ which to me would give you a very high quality display out of an Amiga or ST … so long as your VGA monitor could Vsync down to 50Hz (as I live in the PAL part of the world). At the time I did not have such a monitor. Of course, after getting a Gonbes I kept on searching for the ultimate retro monitor and ended up with a pre June 2005 Dell 2001FP. Pity they are now all over 10 yrs old.

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Using an Arduino Uno to program EPROMs

I have a Willem parallel EPROM programmer (or clone). I bought it when I was trying to burn Amiga Kickstarts, but I’ve used it for burning  27C256’s and 27C512’s as well. I’ve had a lot of weird problems with the Willem. Sometimes it ‘just works’. Other times you tear your hair out trying to figure out whats wrong with it. When I bought it, it seemed like the cheapest way of programming the special 16bit EPROMs used in the Amigas.

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Modifying a PS2 optical mouse for an Acorn RiscPC

So as well as my C128, I recently picked up an Acorn RiscPC. This is my first Acorn ARM machine (I’m politely ignoring all the phones and other modern ARM chip licensed devices everyone typically has). I’d been on the lookout for an old A3000, but they are so rare these days. But the RiscPC is somewhat further along in the evolution of Acorn ARM based home computers …. and is very high spec compared to many of the other machines in my menagerie. It came with a StrongARM CPU, 256MB of RAM, 5×86 card, CDROM and ethernet. In many ways it takes advantage of the technology available in PCs of the time (full IDE for disk drive and CDROM).

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