28 Jul
2014
28 Jul
'14
9:53 p.m.
Doug,
Buffering is definitely an issue. This is the big reason I need to get a program like
kermiot (or xmodem or just about anything) that I can use that will give me some flow
control.
A suggestion of splitting up the hex file in to a bunch of smaller files sounds like a
good idea. If I understand the HEX file format correctly, each line has the start memory
address for that line, so chopping it up and loading all of the pieces one at a time on
the Horizon sounds like it might work. I have successfully transferred a 5k file, but the
one I'm trying to do is 70k. At a worst case, 70k/5 is 14 separate files...
I'm surprised that with all of the cool features that CP/M brought to computers that
flow control wasn't one of them.
Ian
On Jul 28, 2014, at 9:26 PM, Doug Jackson <doug at doughq.com> wrote:
Ian,
I remember the NorthStar - It was a fun machine that I got to play with occasionally at
the local computer shop. I only owned a Pulsar Little Big Board, but it has dual 1.2Mb
floppies....
But your post has reminded me of the dreaded buffer problems I would run into during
transfers.
This was probably the number one issue when I was a youngster playing with CP/M - I went
to great pains to modify the BDOS (?) to provide both XON/XOFF and Hardware handshaking -
that ended up being the solution. Simply dropping the speed down never helped. I wanted
to write a circular buffer but that never happened - and I suspect that the floppy disk
interrupt probably got priority anyway.
There simply was never the capacity to chuck data at a buffer once the disk starts
spinning.
Doug
On 29/07/2014 1:55 PM, dwight wrote:
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From: ian at platinum.net
Subject: NorthStar Horizon Bootstrap Assistance
Date: Mon, 28 Jul 2014 20:29:04 -0700
To: cctalk at classiccmp.org
Hello All,
I've mentioned before that I'm bringing a NorthStar Horizon back to life.
I've managed to get quite far, with a fully functional 32K machine running (the second
32k board has an unknown problem at the moment).
I've used Dave's NSI utilities to create a CP/M boot disk, which is now working.
CP/M is able to format disks, etc. The problem I'm having now is getting other CP/M
utilities in to the machine. I'm thinking that KERMIT is a good tool to get in,
because once I've got that, I can use serial to transfer anything else I want.
I'm trying to follow the kermit-80 documentation about getting a couple of HEX files
in to the machine then using MLOAD to merge them and create the binary.
The problem I'm having is that the main kermit hex file (CPSKER.HEX) is 70k in size.
I've tried both the bootstrap ASM that comes with kermit, as well as using pip, but as
soon as I hit the buffer size and a disk write happens, I get a buffer overflow and the
transfer breaks.
Does anyone have any ideas? I'm thinking that if I could get the kermit binary (or
even the hex files) on to a CP/M formatted NSI image, I could bootstrap that image over.
Does anyone have a binary for kermit for the Northstar Horizon? Is anyone able to create
an NSI image (double density single sided) that contains this binary, or the two HEX files
in it?
Or is there some magical incantation that I might be missing? I've got a very
limited subset of programs on the CP/M boot disk:
A>dir
A: MOVCPM COM : CONFIG COM : ASM COM : COPY COM
A: FORMAT COM : FILECOPY COM : DDT COM : ED COM
A: LOAD COM : PIP COM : STAT COM : SYSGEN COM
A: SAVEUSER COM : SETCPM COM : SUBMIT COM : XSUB COM
A: DUMP COM : DUMP ASM : MEMR COM : MEMR DOC
A: HORUSER ASM : USER ASM : DISKDEF LIB : READ-ME DOC
A>
Thanks in advance for any assistance!!!
Ian
You might just break the HEX file into smaller pieces. Once in the
N*'smemory, you can save them as binaries. Once you have themall on disk, bring them
into memory and piece them together andsave as one binary image.Dwight