2708 EPROM progreammer - old magazines designs

[Dave McGuire]

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.

            -Dave

-- 
Dave McGuire
Port Charlotte, FL