Re: Strange EPROM Adapter Found

[Bryan Villados <news001@macgeek.org>]

[[ This message was both posted and mailed: see
   the "To," "Cc," and "Newsgroups" headers for details. ]]

Cool!!! Thank you very much for the information!

In article <938156600.612301@inv.ihug.co.nz>, Roger Johnstone
<bhmhome@es.co.nz> wrote:

> ----------
> In article <230919992031335129%news001@macgeek.org>, Bryan Villados
> <news001@macgeek.org> wrote:
> 
> 
> >Hi, guys!
> >
> >Digging in my old computer junk, I came across something I'm curious
> >about... My dad (he passed away a while back) used to tinker with
> >EPROMs, and he used to burn them all the time. I found an adapter he
> >made... It's a 24-pin adapter (Textool) and he left in it a 2716 EPROM.
> >I believe he made it so that he could stick this adapter into an
> >existing ROM port (on an Apple II logic board, card, etc.) then pop an
> >EPROM into it.
> >
> >Here's the thing I'm curious about... On the adapter he jumpered pins
> >21 and 24, and pins 18 and 20. What's the purpose of doing this????
> >
> >---
> >Bryan Villados
> >Curator, Apple Museum For-a-Day, Hawaii
> >http://www.macgeek.org/
> 
> EPROMs and mask programmed (mass produced) ROMs have slightly different pin
> connections and so you need an adaptor to use an EPROM in place of a mask
> ROM.
> 
> On a 2716 EPROM pin 18 is chip enable/program, pin 20 is output enable. Both
> of these should be tied low to read from the chip.
> 
> Pin 21 is the programming supply, 25V is applied during programming. Pin 24
> is the normal supply. Both of these should have +5V on them.
> 
> Roger Johnstone