Re: Sol-20 Helios problem

At the time that the NS system came out (1977-ish), it was $500-ish and 8" systems were $2,000+. But then the Tarbell disk controller came out (1978) for $100 or so, and the price of 8" drives dropped to $500. An 8" system then only cost a couple hundred more than a NS system (instead of $1,500 to $2,500 more) and in my circles at the time, the NS system died pretty quickly.


no.spam@xxxxxxxxxxxxxxxxxxxxxxx wrote:
On Thu, 26 Jul 2007 21:59:53 -0400, Barry Watzman
<WatzmanNOSPAM@xxxxxxxxxx> wrote:

There is no need to pull the Personality module, although it does limit you to 48k of memory. There was a modification to the SOL-20 to move the 4K of memory (2k personality module ROM, 1k video, 1k RAM) to 60K (you have to reassemble and reburn SOLOS to do this, but source code is available, so this is easy if you have a 2708 programmer (typically, a Cromemco Bytesaver)). Many people modified SOLOS (the code in the stock personality module, for which, as noted above, source code is available) to include a floppy disk boot command. I myself have a highly modified version of Solos that includes a dump command with hex/ascii, a memory test and a tarbell disk controller boot command.

The Tarbell (and some others) controllers and 8" drives is a MUCH better solution than the Northstar controller. Back when it came out, the Tarbell controller pretty much killed off the NorthStar system, which had been very popular prior to the availability of cheap 8" soft sector IBM standard systems.

Here in the east the reverse was the case. NS* displaced 8" system
where storage was not a factor and cost was. You could get a
complete Horizon box sans memory for what a dual 8" disk and
controller cost (1979-80). The tarbell was not popular around the
LI area (LICA). What I did see was a mix of controllers that seemed
to remain that way till late 1979 when the DD controllers started
appearing. After that 1793/1 based controllers were the rage.

Allison




John Crane wrote:
Bill,

Thanks for the offer. I know the NorthStar option was THE way to go back in the day. But I've been avoiding that route because 1) I don't have a NorthStar drive/controller and haven't seen one on ebay in quite a while. and 2) I've heard (ever since the mid 80's) to avoid NorthStar because of it's disks. Another source I found for those pesky disks is Athana @ about $30/box of 10. They also sell disks with 16 hard sectors for my Micropolis drives at the same price.

Barry,

I've also toyed with the idea of just pulling the personality module (a SOL lobotomy?) and connecting an 8" drive/controller combo and setting up a vanilla CP/M system. I have a couple of dual 8" drive/controller sets just sitting in storage. But since I have lots of CP/M machines already (I count 6 in the computer room right now), not to mention the innumerable $50 Kaypros & Osbornes on ebay these days, it just seems like work spent to destroy something unique in order to make it non-unique. Of course, I realize that was the whole point back in the day. A user wanted to achieve that level of standardization with CP/M. Lifeboat software was truly a lifeboat!


The Micropolis MDOS system works well, but my main complaint is that you can't redirect I/O like you can with the SOL personality module SET commands. It would be very nice to be able to load software via the serial port. So, I wrote a serial communication program in 8080 assembler using the MDOS assembler and line editor. It all went well however only the line editor file format is documented. Meaning that I can load 8080 assembler source code from my laptop and have the program do the translation on the fly and then write it to disk. But I cannot load BASIC source as it's format is undocumented and it uses it's own editor and not the line editor the assembler uses. If I could at least load some BASIC programs without typing in everything from scratch it would be less painful. When it comes to running PT software from MDOS, I haven't tried it. But since they appear to use different memory maps with different "allocated" sections of memory, I would suppose a translation would involve scanning an object file looking for memory references, JMPs, etc. and changing them. And checking for program code existing in the forbidden "allocated" zones, moving it, and changing all internal as well as external references to objects in the zone. It could be done, but it's not trivial.


For now, I'll proclaim the Sol "good enough" and archive it. I still have automatic searches running on ebay that will notify me if NorthStar drives show up. In the meantime, I've got a SWTPC 6800 that's calling for attention.


Thanks all !

-John


"Barry Watzman" <WatzmanNOSPAM@xxxxxxxxxx> wrote in message news:46a51378$0$20567$4c368faf@xxxxxxxxxxxxxxxxx
A better solution is just to use a standard 8" controller and drives .... the tarbell controller (single density) works fine. Hard sector 5.25" media is very difficult to find and only stores 100k.


Bill Sudbrink wrote:
In article <pYidnSTVeI7sGz7bnZ2dnUVZ_sm3nZ2d@xxxxxxxxxxxxxx> "John Crane" <jc email> writes:
I heard they were finicky, but I didn't know it was that bad. I have a pair of Micropolis 5.25 drives already working with the Sol (yes I did remove the Micropolis card before adding the Helios cards to test). Maybe I'll just stick with those. They run MDOS with Micropolis's own BASIC and Assembler. Not too bad, but it's so "non-standard" I feel I'm in my own little world whenever I work on the Sol. I can't run CP/M or PT software under MDOS. I can, of course, still load my PT software via cassette (I loaded the hex codes for some games (TREK80, CHESS, LIFE, etc.)via laptop then saved it on cassette tapes so I could have that genuine 70's feel).

A common solution from the time was to use a Northstar controller and drive.
I have a receipt from 1979 showing that combination was sold retail. If you
can get yourself set up that way, I can provide Lifeboat CP/M images (CBIOS
modified for SOL-20, originally from Dave D's site). The media isn't really
that hard to lay hands on, you just have to plow through lots of 5 1/4, 5.25,
floppy, disk, diskette, 360K, etc. searches on ebay. Most sellers don't
know what they have, contact the seller to be sure that the photo is really
of the lot for sale. Finally, once you are set up and running, you can use
my RUNENT utility to run just about all of the software from sol20.org from
disk.


.

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