2708 EPROM progreammer - old magazines designs
mcguire at neurotica.com
Wed Mar 28 17:03:32 CDT 2007
On Mar 28, 2007, at 3:28 PM, Chuck Guzis wrote:
>> It would be near-trivial to adapt the original design to be driven
>> by a microcontroller, by the way.
> As I recall, the programming algorithm was very simple and brute
> force (fixed number of hits to get a 0). IIRC, there were later
> programmers that applied a little intelligence to the operation.
Yup, it's not an intelligent algorithm. As I recall, this method
was the more common at the time. But under the control of a
processor, one could very easily do a high-speed intelligent
algorithm with the same programmer hardware.
> One could easily build a programmer with little more than a counter
> and a few gates and a control transistor for Vpp. The biggest
> annoyance it seems, to me is the need for several supply voltages in
> addition to Vpp.
Yes, that is a pain. I've recently "conquered" the MC34063
(meaning I now know enough about designing with it that I no longer
pick bits of MOSFET out of my hair when I'm building prototypes), so
now I can go back and revisit all those projects that I've wanted to
build but avoided due to weird voltage requirements. Doing a 25V
step-up converter for a 2708 programmer really isn't that difficult.
Port Charlotte, FL
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