Subject: Re: Strange EPROM Adapter Found From: Bryan Villados Newsgroups: comp.sys.apple2 Posted-And-Mailed: yes Message-ID: <230919992250353399%news001@macgeek.org> References: <230919992031335129%news001@macgeek.org> <938156600.612301@inv.ihug.co.nz> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 8bit Mail-Copies-To: nobody User-Agent: YA-NewsWatcher/4.2.4 Lines: 42 Date: Fri, 24 Sep 1999 08:55:50 GMT NNTP-Posting-Host: 24.31.76.213 X-Trace: news.onlynews.com 938163350 24.31.76.213 (Fri, 24 Sep 1999 01:55:50 PDT) NNTP-Posting-Date: Fri, 24 Sep 1999 01:55:50 PDT [[ 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 wrote: > ---------- > In article <230919992031335129%news001@macgeek.org>, Bryan Villados > 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