New subject: not HARD SECTORS on a PC (was: NorthStar Double Density - DOS low level DCOM function

29 Jun 2004

At 11:40 29/06/2004 -0700, you wrote:
...
 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! 
Nobody said anything about reading/writing hard sectored disks on the PC
- both parties have a functional N* system - I've already written software to
transfer images to/from the my Altair running the N* single-density controller,
(same images work under my emulator) and the PC via serial transfer - all I
want to do is to update that to support double density - that way both of them
can upload/download images to/from the PC, however I don't have the DD controller
to test with, hence my request for some clairification regarding some of the
finer points which are not explicit in the documentation - basically I have to
send it to one of the other involved parties to get them to test it, so I would
like to eliminate the variables as much as possible.

I've already written a utility which allows me to take a binary N* executable,
and transfer it into a N* system by essentially "typeing it" into the N*
monitor (which all N* systems have) via the serial port.

So - by sending this utility, and a binary of the disk transfer to both
parties - they can both move the transfer program unto a n* disk, then use
that to read/write diskette images to/from the PC via serial transfer.

...
 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. 
Yeah - but that doesn't make it any easier in the future, and it's
complicated and slowed by the fact that 10 sector disks are in short
supply - the guy making the copy is in the States, and doesn't have
any disks to spare. I and the guy needing the copy are in Canada - so
for the snail mail technique, I first have to send diskettes to the
States (and he has to import them through customs), then he has to send
them back to me (and I have to import them through customers).

Alternately, I could send him a ZIP containing two PC programs and a N*
binary. He uses the first one to put the binary onto his system, then the
second one in conjunction with that binary to read the disk images into
PC files, which he ZIP's and sends to me).

Next time - 1/2 the work is done, and it becomes even simpler.

...
 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. 
Uh yeah (what a good idea :-) - but to do this, I need to understand
the details of the double-density use of the N* DCOM function (OS low
level disk acccess call) - which is what I asked about (please read
earlier post).

...
   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. 
And what makes you think I am not familier the the PC controller (having
designed and implemented several 756 based controllers from scratch) - the
PeeCee controller has nothing to do with this, which is why I was asking
about the N* DCOM function (part of the N* DOS servies, which would be
booted on a N* system using the N* disk controller, and are used to read/wrote
diskettes using the NORTH START controller).

I don't think I mentioned the PC disk controller in my posting.

Granted - I did not explicitly say I was doing a serial link, however that is
not what I asked about (I have all the info and experience I need to do serial
transfers) - I asked about the N* DCOM call, which should have been enough to
let you know that what I am trying to do is read/write the disks via the N*
DCOM call (ie: N* OS). Refer to my original posting to see that there are a
couple of non-obvious things which I'd like to know without having to "try
it"
remotely a whole bunch of times.

...
 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. 
Got an option board - but why bother - both parties have a running N* horizon
with DD controller - ie: hardware already exists to read/write the disks.

...
 Grumpy Ol' Fred     		cisin(a)xenosoft.com 
I'll say - did you have an answer to my original questions?

Regards,
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

HARD SECTORS on a PC? (was: NorthStar Double Density - DOS low level DCOM function