On 2021-Feb-23, at 1:45 PM, Frank Tuccio via cctech wrote:
On 02/22/2021 01:31 PM, Brad H via cctalk wrote:
A longshot I'm sure - but I am wondering if anyone familiar with MSI
Scentific - SS50 bus system) would happen to have a copy of the
software for their 1702A EPROM burner, I think the model is PR-1. I just
picked one up and am eager to see if I can use it to read/burn 1702As,
something that has been an issue for me for a while now.
Reading them is pretty easy. BURNING them is crazy. They
need an 80 V power supply, and I think you XOR the address
or something as you apply the programming voltage.
Actually, programming a 1702 only requires a -48 volt pulse for each
address. Here's the datasheet:
Ya, but that's with a Vbb of +12V, so the differential required from the power
supplies is 60V.
(Per the datasheet, it was ~ 55V in the 1702 programmer I once had.)
But that's the easy part.
And the semi-complex timing and switched-complementing of the address can be done in
The hassle is that the data lines, address lines and several of the supply and control
lines all have to be switched independently with these high voltages. So it's a small
mess of specialised discrete drivers and hardware.
It's not just pulse a high voltage to one PGM pin like it was for 2716s and later
I don't know what the 2708 (after the 1702, before the 2716) requirements were.