Date   : Tue, 24 Aug 1982 01:18:00-EDT
From   : Frank J Wancho <FJW@Mit-Mc>
Subject: Mainly for N* Users

There is a rather clever release of N* CP/M 1.1.0QD, which allows you
to define a "64K" environment and split the CP/M so that the BIOS can
be located above the disk controller PROM.  Unfortunately, it is too
clever:

Suppose you take the default 64K configuration.  This puts the BIOS at
F300H, and the BDOS is located from D900H to E6FFH.  The coldboot
loader (in your SYSGEN image at 1400H to 14FFH, and loaded at F200H)
copies the jump table from F300H to F332H to E700H.  Note that it does
not copy the extra entry in the BIOS which is described in
DIRDUMP.ASM.

The result of all of this is that BDOS uses the jump table at E700H,
and other programs like EX, BYE, UNSPOOL, and a few others, redirect
I/O by overlaying the jump table at F300H - which is bypassed by the
BDOS!

One solution is to post-patch the jump table at E700H with jumps to
consecutive addresses starting with F300H and incrementing by 3.

Another solution is to patch the coldboot loader - but be careful: the
first byte of the coldboot loader (at SYSGEN 1400H) is the page
address (F2H) of where the coldboot image is to be loaded...

Thought you'd like to know...

--Frank