

If your Osborne-1 Double-density machine has the
MPI drives in it you have probably been using a
utility program called fast to increase the step
rate. The drives run quieter and do indeed step
faster.  If you aren't sure if your drives are
MPI you can tell by looking to see if there is
a switch 'lever' hanging down on the right side
of the drives. If this is the case then you can
make use of the following information.

The problem I've had with the FAST.COM program is
that it is under 20 bytes long but takes up 1k of
disk space. Further, you either have to type in FAST
every time you boot up or (as I did) simply make
FAST the name of your auto-load program. This, of
course precludes the use of the auto-load function
for anything more worthwhile.  I have written a small
routine that sits on the system tracks just above
the area where the 'function' keys are stored. After
a cold boot the routine is overwritten by other
bios stuff but has done it's job by then so it
doesn't matter.

The assembly routine below can be entered in a
number of ways, two of which are the most practical.

1. Create a new CP/M using MOVCPM and save it to
   disk. Use DDT to load the new CP/M and then enter
   the following:

a1f80
jmp e278	;changes the cold start jump to our routine
.		;exit a option
a20f8		;our routine
mvi a,0
sta ef13
mvi a,fb	;restore cold start jump
sta e101
mvi a,e4
sta e102
jmp e4fb	;continue with cold start routines
,		;exit a option

   Now use ^C to exit ddt and run sysgen answering
   the 'source?' prompt with just a carriage return
   and the 'destination?' prompt with the drive that
   contains the disk you wish to modify.

   From then on the system will set the step rate to
   6 ms every time a cold start or reset is done.




2. The other method is to use the DSKNURSE or DU
   utility program:

with the disk to change the system tracks on in the
b: drive and du in the a: drive enter:


du;lb;g0;t1;s7;d;ch78,3e,00,32,13,ef,3e,fb,32;w


After the du prompt returns enter:


+;d;ch0;01;e1;3e;e4;32;02;e1;c3;fb;e4;w;x


The system tracks have now been modified to change
the step rate to 6 ms on each cold start.


THIS HAS ONLY BEEN TESTED WITH A DOUBLE-DENSITY
OSBORNE. IT WILL NOT WORK WITH SINGLE-DENSITY
MACHINES.


Simon Ewins,
676 Oriole Parkway,
Toronto, Ontario.
(416) 484-9427


--------- end -------------------------------------

08/01/83

