Path: utzoo!attcan!uunet!cbmvax!grr
From: grr@cbmvax.commodore.com (George Robbins)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: ROM pinout confusion
Message-ID: <11858@cbmvax.commodore.com>
Date: 27 May 90 16:03:41 GMT
References: <3276@eklektik.UUCP>
Reply-To: grr@cbmvax (George Robbins)
Organization: Commodore, West Chester, PA
Lines: 27

In article <3276@eklektik.UUCP> danbabcock@eklektik.UUCP (/dev/ph1) writes:
> grr@cbmvax (George Robbins) wrote:
> 
> >It has - the extra pair of sockets is there only to support ROMS/EPROM with
> >mutually incompatible pinouts.  They are very likely to dissapear on
> >production systems.
> 
> I hope it's the nonstandard pinout that disappears and not the other!
> I don't understand why the 500/2000 uses a nonstandard pinout; what's the
> motivation? Secondly, since you have to make two sets of ROMs anyway
> (a 16-bit version and a 32-bit version), there's no reason to choose
> an incompatible pinout for the 3000's ROMs (i.e. backward compatability
> is not an issue). Could you please clarify? (thanks!)

I'm not sure what you mean by non-standard.  The ROM pinout used in the A500
and A2000 is the one used by all of the Japanese ROM vendors, who are/were
the only ones offering masked ROM in 16-bit x 128K format.  When the current
crop of EPROM's in the same class came out, the EPROM vendors chose not to
make their pinouts conform to this pre-existing defacto standard.  So, for
pre-production systems we need to support both, although in the long term,
the ROM pinout will prevail.  Perhaps the EPROM vendors will see the light
if they wish to promote socket-level interchangability.

-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)