What Your Old Graphing Calculator Says About Technology

I have an Shapr PC1500 which meets this description. The machine is a reasonalbe pocket computer, it fits into a cradle containing a cassette interace and one of those Alps 4-pen plottre mechanisms. Unfortunately, as wityh many such plotters, the motor pinion gears have split with time, so it's not useable at the momnet, I should have a go at cutting soem replacements...

I also have the RS232 interface for it. Actaully, thete were 2 versions of this. The Sharp one (CE158 IIRC) had both am RS232 and a Centronics interfce. The Radio Shack one (sold for their PC2 machine) only has the RS232 inteerface, the buffer bord (a couple of '04s IIRC) and the conenctor for the Centronics interface are not fitted. The ROM is the same, the commands ot access the Cnetronics interface are there but not documented IIRC> Anyway, I have one of each type. In the spare space in the Radio Shack one I fitted a bit of stripboard containing an ADC0804 ADC chip and a 4-channel analoguemux wired to a DA15 socket, and conencted to the pins on the I/O controller chip that would have been used for the Centronics interface. The result is a combined 8-bit 4 channel ADC and RS232 interface.