Data Technology Corporation
Information

If you have a DTC 5150BX hard disk controller and want to upgrade
your  system with a larger fixed disk or a non standard one,  you
have  a couple of options.  You can get DTC to send you an  EPROM
for about $25 or,  if you have access to an EPROM programmer, you
can do it yourself.

You  have to dump the ROM and change part of the parameter  table
and  load  the	changed code into a 2764  EPROM.  There  are  two
versions  of the ROM.  One will have a CRC of D400 and the  other
will have a CRC of E000.

The parameter table starts at location 21D for the one with a CRC
of D400 and 21E for the other one.  (Add one to each location for
the E000 one.)

The Installation Guide has a list of drivetype switch settings to
set  up for your type of drive.  DTC #7 says:  "Reserved for non-
standard  drives.  Contact DTC for information." This is the  one
you want to use.  The parameter table for this one starts at loc-
ation 28D hex (or 28E if the CRC is E000).  The following is what
goes into each location:

Location       Contents

28D	       Number of cylinders (low)
28E	       Number of cylinders (high)
28F	       Number of heads
290	       Start of reduced write current (low)
291	       Start of reduced write current (high)
292	       Start of write precompensation (low)
293	       Start of write precompensation (high)
294	       ECC burst (Always hex B)
295	       Step rate -- 00=3 milliseconds
03=13 microseconds
05=70 microseconds
296	       Drive ready timeout (19 is a good number)
297	       Format drive timeout (FF is a good number)
298	       General operations timeout (50 is a good number)
299	       Set to 00
29A	       Set to 00
29B	       Set to 00
29C	       Set to 00

In location F02,  put whatever it takes to make the CRC come  out
with zero for the last two digits. Otherwise it will not work.

I  have tried this and It worked for me.  I used a Data I/O  prom
programmer.  If you have any problems,	leave me a message on the
Dallas RBBS.

Jim Finch