There is a potentially serious bug in VDE 2.66, which you can easily fix
by one of two methods: either a patching utility like DDT, SID, or EDFILE, or
using MLOAD with the HEX overlays supplied below. Either way, only three
bytes need to be changed.
METHOD 1. Patching utility
Follow the instructions for your utility to change these bytes:
(a) For VDE266.COM:
Address Old value Change to
29B8 22 01 00 CD A7 29
(b) For VDM266.COM:
Address Old value Change to
29BB 22 01 00 CD AA 29
METHOD 2. MLOAD
Choose the appropriate HEX file (for either VDE or VDM) below, write it
(just two lines) to disk under the name shown, and use the MLOAD utility to
overlay it on your copy of VDE:
The bug involves the code to handle BDOS disk errors, which was modified
recently (version 2.65) to make VDE compatible with ZCPR3. Under normal
circumstances (or CP/M 3.0) there is no problem. But if you ever get a BDOS
disk error (empty drive, etc) under CP/M 2.2, VDE does not properly restore
the BIOS warm boot entry.
Thanks to Gene Nolan (c/o DHN* RCPM, 215-623-4040), who discovered this
problem about a week ago and suggested an easy solution.
----- Eric Meyer, 427 N. Washington #4, Bloomington IN 47401 -----
