From:	CRDGW2::CRDGW2::MRGATE::"SMTP::CRVAX.SRI.COM::RELAY-INFO-VAX" 15-DEC-1989 13:11
To:	MRGATE::"ARISIA::EVERHART"
Subj:	VMS 5.2/5.1 incompatibility

Message-Id:  <8912151744.AA11848@crdgw1.ge.com>
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Date:    Fri, 15 Dec 1989 17:56:12  +0100
From: "GWDGV1::MOELLER"  <U0012%DGOGWDG5.BITNET@CUNYVM.CUNY.EDU>
To: info-vax@sri.COM
Subject: VMS 5.2/5.1 incompatibility

When I tried out some more or less interesting programs from the net,
with "SHODEF.MAR" posted a while ago I hit an INCOMPATIBILITY
between VMS 5.2 and 5.1 SYS.STB, namely

5.1: FIL$GT_DDSTRING = PIO$GT_DDSTRING = 7FFDFF40
5.2: FIL$GT_DDSTRING = PIO$GT_DDSTRING = 7FFDFF70
[this is the place where the default directory spec is stored in P1 space;
as with most kernel mode hacks, it's undocumented and unsupported]

This is a new phenomenon: I was used to see the SYSVERDIF warning
when trying to execute a kernel mode program on a changed system.
However, SHODEF.EXE linked against 5.1 SYS.STB does run under 5.2
without warning (and luckily gives wrong output only).

I took the time to compare SYS.MAP, and found a few more changes,
which do not look to me as being important (mostly related to the
incereased size of SYS.EXE). One symbol even vanished, and another one
had its name changed.

Watch out!

Wolfgang J. Moeller, GWDG, D-3400 Goettingen, F.R.Germany | Disclaimer ...
Bitnet/Earn: U0012@DGOGWDG5         Phone: +49 551 201516 | No claim intended