29 Jun
2004
29 Jun
'04
6:40 a.m.
On Tue, 29 Jun 2004, Dave Dunfield wrote:
Hi Guys,
I am trying to help someone with a NorthStar Horizon that has the double
density controller obtain a copy of CP/M for his system. I have located
someone with the software - not it's just a matter of figuring out how to
move it.
My plan is to write a little utility that will allow the one person to read
the disk image into a file on a PC which can be transferred by email, and
then the other guy can write it out to a diskette - this is somewhat complicated
by the fact that NorthStar allows mixed single/double density on a diskette
(I don't know if CP/M does this or not) - my idea is to read it a sector at a
time, and include a density flag for each sector - this will allow copying of
an single, double or mixed mode disk.
Single/double density is TRIVIAL compared to the fun that you are
about to embark on with trying to read and write HARD SECTORED
diskettes with a PC!
Have you considered the possibility of using the Northstar that
HAS the software to make a duplicate copy, and then physically
transporting the duplicate diskette to the machine that needs it?
Snail mail will get it there eventually.
If BOTH Northstars were to be functional (with system software),
then you could read the disk on the N*, and transfer it through
a serial port. Either directly, or with some PCs and internet
in between. But that won't work if the target N* doesn't already
have a boot disk/system software.
I am very familier with the N* single density
controller (and have a system
Then you must be aware of the HARD SECTORED nature.
When you become familiar with the PC floppy disk controller,
you will find that it is somewhat unwilling to deal with
HARD SECTORED formats.
Of course, you COULD build, from scratch, an auxiliary
floppy disk controller for the PC that accepts HARD
SECTORED diskettes. In fact, MicroSolutions once made
one! NO, it is NOT the "Compaticard"!!
The COpyII option board could be modified to do it,
or you could write software to use a CatWeasel.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
running one), however I have never owned the DD
controller.
The N* software manual fairly consistantly refers to SECTORS as either 256 or
512 byte depending on density, and FILE BLOCKS as 256 bytes - there are two
file blocks to physical sector on the DD controller.
My question is this: On page4 H-1 of the NorthStar System Software Manual,
the DCOM (Disk Command) subroutine is documented to have these parameters:
ACC=NUMBER OF BLOCKS
B=COMMAND(0=WRITE, 1=READ, 2=VERIFY, -1=SING-INIT -2=DBL-INIT)
C=UNIT NUMBER, Bit7=DOUBLE DENSITY BIT
DE=STARTING RAM ADRESS HL=STARTING DISK ADDRESS
My concern is that ACC indicates BLOCKS, not SECTORS - does this mean that the DD
controller can read/write 1/2 sectors, must always begin on an even block number,
or is this a typo and it really refers to 512 byte physical SECTORS.
The question also applies to the HL parameter - is this the starting address in 256
byte BLOCKS, or 512 byte SECTORS?
I would have assumed that the low-level command would only work on SECTORS, however
as noted at the beginning of my message, the manual is fairly consistant elseware
to use BLOCKS for 256 byte units, and SECTORS of physical disk units - the use of BLOCKS
here would imply 256 byte logical units.
This was never an issue on my SD system as BLOCK=SECTOR=256 bytes - both are
interchangable.
Can anyone with expereience on the N* DD system help clairify this issue? As I do not
have a DD system to test on, it would save me considerable time.
Thanks,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Vintage computing equipment collector.
http://www.parse.com/~ddunfield/museum/index.html