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Back in the day, I cobbled together a few stripboard based expansions for the Dragon, this probably being the pinnacle: https://www.onasticksoftware.co.uk/dragon/expansion-board-photo-large.jpg which towards the end, felt was getting a bit on the mad side. However Bob's board is possibly a work of s...

Probably best not to look to closely it's most likely a complete bodge...

Hi all, It's entirely possible someone may have already done/attempted this, regardless this was a quite fun project and a pleasant change to do something with the Dragon again (it's been some time). So for anyone remotely interested, here's my project page https://github.com/fridgemagnet3/uip/tree/...

Transpires the issue was down to dodgy(counterfeit?) MAX3232 chips that I'd bought direct from China. Having sourced one locally (at probably something like 6x the price), things started behaving correctly.

Thanks for the reply. Hi, Just some thoughts here; 1) Are the earths connected correctly? A pulse train can cause swinging voltages when there is floating connections. 2)MAX3232 is a low current device and perhaps the loads being put on the chip is causing the swings. Do you have a MAX232 to try in ...

Hi all, In possibly a short lived bout of enthusiasm, I've dug out one of my old Dragons & have been attempting to do something vaguely creative with it. Part of that has involved attempting to connect the D64's serial port to a UART on a microcontroller & I've been using a max3232 to perform the le...

Thanks that helpful. Since there doesn't appear to be any additional cap on the original D64 schematic, sounds like they went with the approach that it'll probably work most of the time and that's good enough. It's also possibly the problem I'm seeing where I think it's right on the edge of sometime...

HI all, Wondering if someone can assist with a query around the crystal oscillator for the 6551 on a D64. Am fairly sure mine is dodgy, difficult to tell because things seem to spring back into life whenever I attach a probe on it.... Anyway, I've bought a new one unsurprisingly it's somewhat smalle...

Ah, great I shall download it and have a play. Thanks for your efforts, wasn't actually expecting anyone to "fix" it was more pointing out the anomolous behaviour!

Hi Pere, So it appears the board lost my post I wrote yesterday to you (and you've moved on a little)... I (attempted) to say I was skeptical that it was the MAP0/1 switch (for one thing, the game was made in 1981 and I'm not sure there were any 64K variants around then, or possibly even disk cartri...