[sebhc] Re: Re-creating actual floppies from archive
robin.england at dial.pipex.com
Mon Mar 27 06:35:30 CST 2006
Thanks (again) for your valuable assistance! BTW I hope you are feeling
Unfortunately due to my job I don't get much free time to spend on my hobby,
but this weekend I was able to finally spend a couple of hours in my
workshop and got to the bottom of the serial problem I was having! At last I
have your disk transfer program working fine now!
The cause of the lack of serial comms was actually that the 8250 itself was
faulty. Talk about bad luck; I had originally discounted the serial card
having a hardware fault because I tried swapped serial cards between my two
H89s and this had not fixed the fault. As it turns out, BOTH the serial
cards had duff 8250s in the LP port circuit !
In the end, I swapped an 8250 from one of the other ports on the card to the
LP section and your loader started to work fine. I can't imagine why the
8250s on the LP port on both machines should have both suffered the same
fate; the line drivers associated with the LP port on both serial cards are
absolutely fine. I'd have thought that if someone has mis-connected the LP
port on both machines, or subjected it to static discharge the line drivers
would have been the first to go!
There was one other problem that's worth mentioning for those who also want
to use your H89TRANS. On my pure DOS machine I have Windows 3.1 installed
and as is usual with Win3.1 installations, I also have SmartDrive installed.
When I initially got your loader program communicating I found that at some
random point during the transfer of data between the H89 and the DOS PC, the
communication would suddenly stop. However, when using the floppy drive (on
the DOS PC) as the source or destination, the problem did not occur. I found
that not loading SMARTDRV.SYS on the DOS PC fixed this and allowed the data
transfer to complete successfully.
I've now saved the loader on the H89 to a new disk successfully so I don't
have to re-enter the loader into the H89 each time. Also have successfully
'imaged' one of my original disks and have written it back to another (blank
but INITed) disk with no problems.
I've only two disks that came with the machines, both are HDOS with INIT,
SYSGEN and one has BASIC, so I'm looking forward to playing with some of the
images that are now in the archive.
I also got myself a Z80 assembler (freeware) from Programmer's Heaven which
works fine (I converted your source listing for the loader from 8080 to Z80
opcodes successfully and it generates an exact (hex) listing to your octal
listing for your 42 byte loader which was reassuring!).
BTW, another approach I thought about trying was to use a different serial
port in your loader program by changing the base address (0xE0) but I can't
find a map of I/O addresses for devices in the H89, is there a definitive
Also, can you (or anyone) explain the significance of the volume number to
me? Your program allows you to set (override) a volume number or take it
from a disk image. I assume that this is the 'unique volume number' that you
are asked to input (from 1 - 255) when INITialising a disk. What is the
importance of this (i.e. will setting the wrong volume number when creating
an actual disk mean that the disk won't work?).
Thanks again for your help!
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