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1979-12-31
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*** Microbee Bios ***
by Simon Gerraty 1986
This file describes the current versions of my modified bios for the
Microbee range of computers. All have been developed on a 56k APC. The bios
is mainly intended for 56k owners who wish to use 80T drives eg. 3.5" and for
Computer in a Book (CIAB) owners who wish to use anything other than single
sided 80T 3.5" drives. The current versions are:-
Version A B C D Memory @ E000h
1.2 DS40 DS40 SS80 DS40 ROM *
1.3 SS80 SS80 DS40 SS80 RAM *
1.4 DS80 DS40 DS40 DS80 ROM *
1.5 DS80 DS80 DS40 DS80 RAM *
1.6 DS80 DS80 DS40 DS80 ROM *
1.7 DS40 DS40 SS80 DS40 RAM *
1.8 SS80 DS40 DS40 SS80 ROM *
2.0 DS80 DS80 DS40 DS80 ROM or RAM
2.1 SS80 SS80 DS40 SS80 ROM or RAM
2.2 DS80 DS40 DS40 DS80 ROM or RAM
3.0 DS80 DS40 DS40(L) DS80(L) RAM
3.1 SS80 DS40 DS40(L) SS80(L) RAM
4.0 DS80 DS80 DS40 DS80(L) ROM/RAM [Premium also]
NOTE: All machines with ROM at E000h will need a very slightly modified
boot rom, there are no monitor functions lost, all you will notice
is a shorter Monitor signon messege. If you are currently using the
scratch location at DF46h, let me know, I have versions of the rom
that use different locations.
All those marked above as SS80, the allocation and directory check tables,
are sized for DS80. This means that if you wish to patch the bios to boot up
with DS80 instead of SS80, only the DPB address in the appropriate DPH need be
changed. The addresses are as follows:
SS80 at D687h (standard CIAB format)
DS80 at D699h (Dreamdisk DS 80T 790k format)
DS84 (4k BLKs) at D6AB (Peter Broughton's)
DS40 at D6BD (Standard Microbee DS 40T 390k)
Addresses are those that would appear in the DPHs (look at 1fc0h in
sysgen image). Use DDT or CEBUG (included with distribution as CB.COM) to
change the values in the DPHs at about 1fc0h. To change drive D from DS80 to
SS80 change the byte at 1ffeh from a 99h to 87h. Note changing drive A involves
patches to the warm boot code in the bios and the boot sector, as well as the
DPHs, for most users a new system is a simpler alternative. For instance, if
the above is not enough, information for you to change your, boot drive from
single sided to double, then don't attempt it, call for a new system.
Due to the difficulty users have had installing new bios versions themselves,
and compatibility problems with different versions of ZCPR2, I have decided to
supply and install all systems myself. As a result, and also to justify further
developements, I am charging a small fee. Each system is supplied with a sysgen
program, that contains the system image (and the user's original BDOS), and the
appropriate config utility. Some people have commented on the names of these
files, for instance the sysgen file for version 3.1 would be:
Z2SS8031.COM
^ ^ ^
| | |_______________ version number 3.1
| |___________________ Boot disk is SS80
|_____________________ Command Processor ZCPR2
The matching config utility would be CNFG31.COM
Each system is also supplied with several public domain utilities (which nobody
should be without) A copy of Mark Bishop's SETDISK utility is also included
with some abbreviated names at the start - to match those above.
Type SETDISK.WST to see what I mean. ZPATH.COM allows the external search path
used by ZCPR to be displayed and/or altered. Type ZPATH ? for usage.
Each bios supports and is supplied with ZCPR2 (ZCPR1/3 also). All are compatible
with Mark Bishop's SETDISK utility, as well as TELCOM, and every other piece of
software I have tried. I have left the bios type byte equal to 01 so as not to
require any mods to Telcom etc. for this reason, I have clearly put both the
version number and date of assembly on the BIOS and CONFIG. Be very sure to use
only the appropriate config - otherwise you will clobber your system!
The appropriate sysgen and config utilities are also supplied. It is important
that utilities such as sysgen and config, which do direct disk IO (by-passing
the BDOS and BIOS) be run from the correct type of drive. For instance, if
your boot drive is DS40 then you must run config from a DS40 drive, otherwise
you will here funny noises as your 40T drive tries to step to track 159!!
Similarly sysgen should be run from the correct drive.
You may notice that the system error messeges are very criptic such as;
D => A: instead of " Put disk D in drive A and press RETURN ", well where
do you think I got all the space for upto 3 DS80T drives? The messeges all
mean exactly what they used to, they just say it in as few characters as
possible. Instead of "Bad System, change disk and press RETURN to try again"
you will see "SYSTEM!", as long as you remember to press the C/R key one word
is enough.
Currently the bios only supports the hardware you have, that is, you can't
run 40T formats on an 80T drive (and have them read by a normal 40T drive), the
main reason is that I can't afford an 80T 5.25" drive so don't have the need.
Also at present 8" drives and formats with 1k sector size are not supported.
ZCPR1 ZCPR2 and ZCPR3 are all currently supported - give me a call if you
require 1 or 3.
Note: Version 2.x will run equally well on a 56k or a CIAB, and still supports
up to 3 ds80 drives. (Unless requested otherwise, V2.x will be supplied)
Version 3.0 will only run on a CIAB, and is intended for those with a 3.5" and
a 5.25". V3.0 lets you run a logical drive on A: and another on B:!
(in versions 2 & 3 the system messeges are even shorter!
- eg SYS instead of SYSTEM!)
Version 4.0 is intended to boot equally well on a premium, as any other system.
ROMS supported at the moment are:
BN54 (56k and 128k), BN55 (CIAB), (and BN56 (premium 128k) v4.x only)
If you are using my bios - leave me a messg on the BBS or see me at a meeting
and let me know if your happy with it, or if you have any suggestions for the
next version.
Simon Gerraty.
21 North Ave
Moorabbin Vic, 3189.
ph (03) 557 2501 AH
you have any suggestions for