newbie building a scratch-built computer

Hi, It is a *SERIOUSLY* useful device....it'll even emulate RAM, which is surprisingly useful when debugging code. :-) I first came across the S3 in '89, it was standard equipment at the company I was working for at the time. It's one of the few times that I have been genuinely blown away by a piece of technology. A sort of "Eureka" moment. Even then I couldn't afford (well, justify) the cost of getting one to use at home. In the end I picked this one up in '97, from the small ads of the local paper, for ?35! It had been dropped, so the case is pretty badly damaged, but other than needing an new Ni-Cad battery pack it's fully functional. Or at least it was, I seriously need to overhaul it. The irony is, I'm pretty sure this unit is one of the very ones I used between '89 and '91. The guy I got it from bought it at a "clearout" sale at Aston Science Park in '91....which was when the aforementioned company I'd been working for, on said science park, closed down.... :-) LOL, good point. I actually built my first EPROM burner from scratch too (though I never built an EPROM emulator). I had little choice, as an Atari user my options for off the shelf programmers were very limited - most connected via RS232, no use to me as I didn't have the 850 serial/printer interface module. And the only other one I remember would only work in an Atari 800 as it plugged into the right hand cartridge port (I, of course, had a 400). So I threw together a very simple design which connected to the machine via it's joystick ports. The joystick ports were connected to a 6520 PIA inside the machine which gave me two 8 bit I/O ports to play with. Used one port to pass the data to be burned, and used the other to provide assorted control signals - like the programming pulse, clocking/resetting a pair of 4040 counters which provided the address to the EPROM (I said it was simple), etc. Worked surprisingly reliably. I've never actually seen one of those for real, just pictures. Is it just me, or did they use a very similar case to that of the ZX-80? Certainly, the bottom part of the case looks identical in the pictures I've seen. TTFN - Pete.