Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!apple!oliveb!felix!dhw68k!thecloud
From: thecloud@dhw68k.cts.com (Ken McLeod)
Newsgroups: comp.sys.mac
Subject: Re: How do I find the ROM version?
Message-ID: <26697@dhw68k.cts.com>
Date: 25 Sep 89 12:59:26 GMT
References: <10513@ipl.jpl.nasa.gov> <4325@internal.Apple.COM>
Reply-To: thecloud@dhw68k.cts.com (Ken McLeod)
Organization: Wolfskill & Dowling residence; Anaheim, CA (USA)
Lines: 35

In article <4325@internal.Apple.COM> dwb@sticks.apple.com (David W. Berry) writes:
>In article <10513@ipl.jpl.nasa.gov> dlv059@ipl.jpl.nasa.gov (Dave Votaw) writes:
>>We have MacEnvy, which is supposed to tell us this information, but the
>>version we have (1.0d8) gives the same ROM data for an old Mac II (1987) 
>>and a IIx. Is there a newer version?
>	Perhaps that's because the II, the IIx, the IIcx and the SE 30
>all use the same version of the rom, 0x178.  The "version" of the ROM
>is revved much less frequently than one might assume.  If you need to
>know what machine you're running on see the SysEnvirons call.

  Exactly. Both MacEnvy 1.0d8 and 1.0 report the ROM *version* as 120 ($78)
for the II and IIx; this is correct. HOWEVER, the ROM in the IIx has a
different *revision* level. Just because the version number is the same
doesn't mean the ROM is; for example, a lot of people don't know that there
are two revisions of the Macintosh II ROM (the older rev can't address more
than 1 megabyte of RAM on a NuBus card). The ROM in the IIx, IIcx and SE/30
is different from either of these, yet still is "Version 120".

  Now, unfortunately, the *revision* level for 256K ROM machines was
incorrectly reported in MacEnvy 1.0 (which assumed it was the high byte of
the word at an offset of 8 bytes from the start of ROM; this is actually
something else entirely.) The "real" way to determine the ROM revision is
to compare the ROM checksum (first four bytes of ROM) against known
checksum values... the checksum uniquely identifies a particular revision.

  MacEnvy 2.0 now displays the checksum along with the version info (and
revision level, if known). I'll be releasing it as soon as I get some
quality time on a IIci :-)  Until then, it's still vaporware; please stifle
the impulse to mail me immediately. ;-[

-- 
==========     .......     =============================================
Ken McLeod    :.     .:    UUCP: ...{spsd,zardoz,felix}!dhw68k!thecloud
==========   :::.. ..:::   INTERNET: thecloud@dhw68k.cts.com
                ////       =============================================