janbredenbeek wrote:
I have also written software for a home-made Eprom programmer (of which I still have the schematics and the prototype on Veroboard!) and while it will probably not have as many features as QEP III it's still useful for reading and writing Eproms up to 27512. It also includes a Hex file editor.
Jan.
Can it program 2732 as well?
I'd be interested in those infos.
Kind regards Paul
It was designed for 2764-27512 but if the 2732 is electrically compatible with 2764 it can probably program them. IIRC the smaller eprom types need 21V programming voltage and this is achieved with a step-up inverter using a TL497 circuit (see attached diagram). As it was designed in 1988 I'm not sure if all components are still available now (and with today's components it would probably be possible to make a more efficient design).
I have a copy of your schematic, which you sent to me in the 1990s.
I am sorry that I did not get around to making the Eprommer.
Maybe this is something that could be done, with a professionally made PCB.
I wonder if the 8255 and handful of 74LS chips could be replaced by a single FPGA - after all it's just a matter of driving some 24-odd data and address lines (and allowing for Vpp etc to be applied to some lines). It would also be nice if the Vpp voltage could be set in software rather than via the manual switches.
The reason why the programming software itself is in EPROM is because of timing - that's also the reason why it runs only on an original QL. This is a bit awkward as you cannot have a Trump Card or Gold Card attached at the same time so you have to load the code to be programmed via MDV or NET using a second QL. (This is where a backplane would come in handy if you have a separate disk interface).