Re: Restoring a NorthStar Horizon, problems with SRAM board
- From: Dave.Dunfield@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (Dave Dunfield)
- Date: Fri, 01 Jun 2007 12:28:29 GMT
I am trying to determine if the computer is reliable or not. Do you
have any suggestions on what I can run from a NS DOS 5.1DQ disk to
verify the computer is working reliably? I have run various monitor
programs and BASIC and all seem to work as far as I can tell. The
system stays up for extended periods but I do not have any way to
really gauge whether it is working well or not. Also, I have many
disks which came with it but I do not know which ones are blank or
not. I can do LI commands from the DOS prompt but that does not work
on all disks. I think these disks are a collage of many systems disks
including a NorthStar Horizon and I am not sure what is in there.
The N* monitor has a memory test command - One version of the monitor
can be configured to run stand-alone - use that one, and test the blocks
of RAM above and below the block occupied by the monitor for an
extended period of time (each) - This will give you a pretty good indication
of the RAM.
There is also a DT utility on disk - you will need a scratch/blank disk,
and it will test the disks read/write - of both of these tests pass, your
system is in pretty good shape.
The disks that do not accept 'LI' - Have you tried both UPPER and
lower case? - N* requires upper case, and most I/O routines do the
translation, but some do not - It's also remarkably easy to corrupt
the command table entry for "LI" before saving a customized version
of DOS - do any of the other commands work on these disks?
If you get no response at all, it could be that the I/O routines are
customized for a different input device...
All the monitors on the NorthStar boot disk have been customized to
use the Flashwriter for video output and the parallel keyboard for
input. All except the M5700 monitor which uses the first serial port
for IO. After I review NST.ASM, which appears fully correct for the
default case my machine is, I assemble the NST program using ASMZ80
per instructions and that goes fine. Then I launch the NST program
with default parameters "NST UH NST" which also goes fine.
Just keep track of the memory location used by the monitor and
the NST program - this is covered in my information. Depending
on which N* monitor you use, you may have to move the data
transfer buffer.
I am running full screen on my laptop and when I start the M5700
monitor on the NorthStar, I see "MONITOR 5.1" come up on the laptop
screen and a ">" prompt. I can type return and simple commands to the
monitor and it seems to work.
However, here is where the problem occurs: When I type DS 2D00 at the
">" prompt per instructions, I get the prompt for the first value and
I press F1 to send the NST file. Then things start going wrong
because some of the characters are just dropped and the NST file is
never completely uploaded.
Some hex numbers come across fine, others only a single character,
some none at all. Usually, it gets several lines down and stalls out
the entry program. Pressing return at prompt regains control and
returns me to a ">" prompt.
I expect the problem is that you have modified I/O drivers in the
Horizon monitor.
You may need to poke around with the monitor and determine what the
N* serial port is being set to - it should work fine of they match.
You could try the paremter: U=0'-'~S or U=1'='~S
To maximiize transfer speed, NST allows for characters being buffered
in the uarts on RX/TX - the default U=2'='~S allows for two outstanding
characters (one in each direction). The one suggested above allows for
0 or 1 oustanding characters, so the monitor will send a character and
wait for the echo before sending the next character.
You can also use my HDM80 with appropriate U= parameters. In this
case you would need to download the full "DOS + client" image for
NST (assuming you started the system from the HDM80 ROM).
I read the instructions again but maybe I am not understanding what is
happening here. I tried varying the communication parameters but only
C=1:81N9600 seems to work. C=1:71E9600 also works but has the same
characteristics. Changing baud rate does not work for other than
9600. Is there a way to specify hardware flow control of the serial
port? Does it affect serial communications?
When I press F1 at the regular monitor prompt (not in the
instructions, I know, just an experiment) I see the string of hex
numbers being sent but they seem awful slow for 9600 bps.
Win2k often takes 100ms to report a recived character to the DOS
box ... this slows down single-character at a time transfers
considerably - It could also be that NST is waiting for the echo
and not getting it, or getting out of sync from the monitor '?'
error response and timeing out to recover.
I tried the W= parameter as it sounded promising that maybe Win2K was
interfering with the serial port somehow but I do not know what a more
reasonable value would be if 18 is the default. Changing the value to
a larger number does not seem to have an effect. I do not know why
and I don't really understand so I leave it alone.
It should be fine under W2K - I've seen XP take *10 seconds* to report
a character received by the physical uart up to the DOS box ... 2K is
usually on the order of a few 10s of milliseconds.
What does seem to solve the problem is the U= parameter. The default
of 2 is apparently not working on my computer so I tried U=0"="~S but
that did not work either. However, when I tried U=1"="~S it seems to
work. Then I was able to get the NST program to upload the NST stub
program on the NorthStar just as I would expect. Once that occurred,
I just followed the directions and did a "JP 2D00" and the monitor
prompt disappeared. I am not sure why this worked but I suspect it
has to do with my old and slow laptop running Win2K and having less
than ideal serial port drivers.
Could be. Best to do this stuff under real DOS or Win9X (which is
real DOS) - The further you go up Microsloths OS "progression",
he worse the DOS box works, especially for serial comms.
It all looks good so I press F10 to exit the upload terminal and run
the NST command locally on the laptop with "NST RD MASTER". The
computer is busy for a while and the NorthStar is reading sectors and
the laptop is recording them as you would expect. After a while, it
finishes and there is a MASTER.NSI file in my C:\HORIZON directory.
With the new master boot image recorded, I load the HORIZON simulator,
mount the NSDOS50D disk in drive 1 and MASTER in drive 2. Start the
simulator and do a LI command at the DOS prompt. I can see the
simulators boot disk directory. Do a "LI 2" command at the DOS prompt
and I see the MASTER boot disk directory I just recorded. In addition,
I was able to start the M5700 monitor in the simulator and it appears
to run fine.
Good.
By the way, I was also able to put some disks in the drive 2 of the
NorthStar and get them to give a directory listing. However, there
are other disks which when I type "LI 2" on the NorthStar NSDOS
prompt, I just get garbage. I do not know if this is another
operating system like CP/M or is it a single density floppy disk or
just a corrupted disk. There are many disks like this and with rather
mysterious contents.
If is is single-density, it should still show a directory (DD DOS handles
both SD and DD disks) - most likely it's CP/M, or possibly another OS
(UCSD for example).
Do any of these boot? (ie: does another OS come up) - keep in
mind that they may boot to the serial console or your flashwriter
depending on how they are configured.
If this does not get you anywhere, read some of the disks into
images. Then you can boot CP/M on my simulator and see if you
can read the directories (indicating that they are CP/M disks) -
if that does not work, try hex-editing the image files and look for
ASCII strings that might identity the content.
Again, sorry for the long message but I would like to keep you and
anyone else interested up to date on my progress on restoring the
NorthStar Horizon. There are still many things to do on this
wonderful old computer but tonight has been a good night so that is
all for now.
Excellent - Glad to know it's alive and well!
PS, one profoundly ironic thing I noticed is my NorthStar takes about
5-10 seconds to boot from power off to DOS prompt. My laptop running
Win2K and easily 2 orders of magnitude greater processing power, takes
about 10 minutes to boot. This drives me nuts. How is it that
computers actually boot SLOWER as time progresses? :-)
"Progress"...
Dave
--
Dunfield Development Services http://www.dunfield.com
Low cost software development tools for embedded systems
Software/firmware development services Fax:613-256-5821
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