This document copyright Herbert R. Johnson 2007. Last updated Nov 19 2007.
Price and other information can be found in this notice.
To return to the S-100 home pageclick here.
A Northstar system I repaired in 2006 and later is on this Web page link.
In due course I'll have a better history of Northstar computers here. A very early S-100 manufacturer, they were one of the first to offer a floppy disk controller and floppy drive and with their own DOS. Their early systems used hard-sectored diskettes; they continued to use hard sector for some time. They offered a floating point card built from programmed chips (PALs). They also built an integrated system with keyboard and CRT display (Advantage model). An informative NorthStar Web site established by NorthStar employee Alan Bowker is at this site as of 2007.
In Aug 2006, Northstar software developer Dave Ashley posted the following in comp.sys.northstar, and permitted me to post it here:
My dad's name is Allen Miller Ashley. He developed lots of software for 8080/z80, then in the 80's did a lot of business writing cross assemblers. As I recall when [my Dad and I] worked on [the Comstar compiler] I was 14 and a freshman in high school. This would have been about 1979-80. The compiler took NorthStar BASIC programs and produced Z-80 assembly language. This would then get fed to my dad's existing compiler/linker and you'd get a binary, presumably behaving the same as the original program, only it would be much faster and also obfuscated (harder to reverse engineer object code than a BASIC program).
Also for small programs the resultant binary would be smaller than the BASIC interpreter plus the BASIC program. I remember the documentation had a graph of the likely cutoff point where your BASIC program would end up compiled larger than the original source plus interpreter. It was pretty big though.
The whole package was $400. The pricing was set to match Microsoft's compiler, which worked for Microsoft BASIC. Maybe $395. Back in those days M$ was just another pissant.
I wrote a bunch of the support functions. I remember I wrote the PRINT USING implementation and I had to run exhaustive experiments on what N* BASIC would do to make sure my version matched. The behaviour was documented but still you'd need to make it match exactly.
I remember my coding style drove my dad nuts. We were programming in 8080 or z80 assembly language. I'd have some routine that would do something, and it would call some other routine. Since I was writing both routines, I'd pass arguments in registers in whatever way was convenient. Sometimes I'd use the accumulator, sometimes D, sometimes H. Sometimes DE would be a pointer, sometimes HL would be. In effect you wouldn't know how to call a function unless you went and looked at it. We weren't much on comments. What I was trying to do was avoid lots of push/pops and utilize all the registers fully. Net effect was small, efficient code but it wasn't really maintainable by other people. That didn't matter since I knew how all the functions worked together...
My dad did the expression evaluator, which would have been pretty complicated for me to attempt at the time. I think I did the file IO stuff also. It's difficult to remember all the pieces. I think the project went on for 3 months or so. It was good money for someone my age to be making.
I got interested in digital electronics and spent some of the money on parts + other stuff.
I'd guess we sold between 200 and 300 copies of the compiler. Probably not more than 500. I think later my dad dropped the price to $200 and sold some more. I never paid much attention to the business details.
Hope the above is useful. - Dave Ashley, Aug 2006
By arrangement with Barry Watzman, I have the following disassembled
Northstar software on my Web site for download:
NSDOS.PRN, DOS version 2.? disassmbly printfile;
NSBOOT.ASM, disassembly of disk boot code
It's easy to "flip" or "reverse" the cable connector between the floppy controller and the edge connector on the drive. Andrew advised me of the risk this poses to Northstar floppy controllers, in response to some comments of mine as below:
> Most of the time, when a floppy is cabled "backward" - that is upside > down - the drive light comes on IMMEDIATELY when the drive is powered. > That's because the drive select lines are active low, and grounding them > will "select" the drive. Of course the cable has to be hooked up AT BOTH > ENDS for this result to occur. I"ve never known this mis-connection to > damage the drive, just power down the stuff and flip the connection. > Hooking up the drive to the WRONG connector could be a disaster, > depending. - Herb Johnson
Andrew replied: I have seen this often. On PC controllers and drives it usually means nothing but on NorthStar controllers, it is instant death for the controller and the drive. The funny thing is that the red stripe on PC floppy cables is opposite to what it means on NorthStar cables. Now I never know which is which without testing to see which pins are grounded. It just depends so I like to be extra sure before taking the plunge with nearly irreplaceable items.
As a precaution, I use a separate power supply for the drive and attach the cabling to the host computer with everything off. Then I turn on the drive's power supply, while keeping the computer off, and if it does what you describe, I know the cable is hooked up backwards. Since I am sensitive to this issue, I rarely ever see it but it might save my FDC someday
[As to where this is documented,] it is mentioned at the very end of the NorthStar MDS-A-D manual, revison 1, page 40, errata and additional information, paragraph #2. - Andrew Lynch
Here's a copy of that: "Applying power to a disk drive while the ribbon cable is incorrectly plugged in to either the drive or the controller can DO DAMAGE TO THE DISK DRIVE! It is very important that the instructions given in the CABLE CONFIGURATION section of the MICRO DISK SYSTEM document be followed very carefully. DO NOT follow the instructions in the OEM manual and DO NOT use the pin 1 mark on the ribbon cable plug as an indicator of how the plug should be connected." - Herb Johnson
disassembly, NorthStar DOS2 and BOOT2, disassembled by Barry
Watzman. 20 pgs. Also available here on my Web site by
permission for download, see above.
disassembly, "NOrthStar DOS2 and BOOT2. Assembled without errors to
original." Well commented. Also PROM boot code. 20 pgs.
No guarantees on this!
disassembly, "DOS 2, BOOT 2" (simple disassembly, no comments). 22 pgs
No guarantees on this!
Disassembly, NorthStar DOS release 4 Aug 1978. 25 pages
No guarantees on this!
disassembly, PROM from N* DD disk controller, 2 pgs. No guarantees!
disassembly, NorthStar Double density DOS file. DOS 5.1 1979.
26 pgs. No guarantees on this!
Horizon HD-5 HD5x Hard disk Installation Guide, 1981. 20 pgs
Z80 Macro Assembler manual - copy, ask
HRD-Z manual - copy, ask
Hard Disk Operating System (HDOS 2.1.X, 1982)
I/O entry points, routines included. 210 pgs
Northstar User Guide (unpacking, use) 16 pgs
Northstar advertizing and flyers, 8 pgs
Lifeboat Assoc. CP/M 2 on NorthStar DD/QD User's notes, 25 pgs
HRAM User/Technical manual 66 pgs
Micro-Disk System MDS-A manual (rev 5 or no rev) 32 pgs each
Micro-Disk System MDS-A-D double density manual (rev 2);
AD3 schematics, 1979 errata: 40 pgs
Micro-DIsk System MDC schematics ONLY, 4 pgs.
ZPB-A Manual, 33 pgs
ZPB-A Manual, rev 3, 34 pgs
North Star Disk Operating System Ver 2, 20 pgs
North Star Disk Operating System Ver 2 release 2 rev 5, 20 pgs
North Star System Software Manual Soft Doc, rev 2.1A, 260 pgs
North Star System Software Manual Soft Doc, rev 2.1, 260 pgs
North Star System Software Manual Soft Doc, rev 1, with errata, 260 pgs
North Star BASIC Version 6 Ver 6 FPB rev 5, 30 pgs
DDSC #1, The DOS mover (relocating the DOS), 18 pgs
North Star Monitor, Ver 1, 14 pgs
Release 4 System Software changes, June 1978, 11 pgs
Diskette Controller schematics, 4 pgs
Floating Point Board, 22 pgs
Advantage PIO PCB schematic, 2 pgs
Advantage AVD PIO Parallel schematic, 2 pgs
Northstar HRZ-MB-4 addenum, schematic (motherboard), June 1980, 10 pgs
Northstar 32K RAM, 2 versions, 40 pgs
Northstar Horizon Computer System manual, Double Density: includes
MDS-AD2, HRZ-MB2, power supply schematics, assembly and descriptions,
HRZ-D Version 1. (yellow paper cover) 92 pgs
Northstar Horizon Computer System manual, Double Density, 25011B: includes
MDS-AD, HRZ-MB, power supply schematics for 1977-8,
technical descriptions. Blue/white cover. 64 pgs
RAM 16A manual - copy, ask
BASIC cross reference - copy, ask
Engineering drawings available: schematics, circuit board layouts,
parts lists, mechanical layouts. Contact me for details, unusual
"inside" information from NorthStar products as follows:
HRZ chassis, motherboard (120V or 230V)
HRAM (32K, 48K, 64K)
HRZ-HD5 (including power supply, cables)
ZPB-A
HRZ-UP8 (including PROM source listings, schematics; 26 pages
HRZ-TIO (paddle board)
Horizon 8/16: fabrication, power transformers, chassis
RAM 32-A (schematic only)
Additional manuals as of April 2004: all by Northstar unless noted otherwise
Disk operating system Ver 2 rel 3 1977 revision 5, 18 pgs
Hard Disk System users manual #25031B, w/schematic of HDS-18, about 150 pages
ADVANTAGE user manual #0451, 1981, hard drive system, some source code, 66 pgs
HSIO-4 User/Technical manual 00187b, 1981, 106 pgs
System Software Manual, rev 2.1, over 100 pgs
Addendum to System Software Manual, rev 2.1 1980, 18pgs + 6 pgs additional
BASIC Ver 6 FPB 1977 rev 5, 26 pgs
G-CPM preface #00482RD1, 1981 (graphic CP/M), 80 pgs
Monitor Version 1 Rev 1 1977 14 pgs
64K RAM board Rev 1 1977, 40 pgs
64K RAM board rev 2 1978, 40 pgs
Microdisk System manual, MDS-A D, DD, rev 2 1978, 40 pgs
G-DOS Disk Operating System manual (graphics), #00485 RD1 1981 108 pgs
Soft Doc System Software Manual rev 2.1 1979 about 100 pgs
Soft Doc Errata Rev 2.1A 1979 10 pgs + 18 pgs notes
Z80A Processor Board ZPB-A rev 1 1977 34 pgs
User Guide to NorthStar Basic by R. R. Rogers, Interactive Computers publisher, 240 pgs
ZILOG Z80 CPU tech Manual (distributed by N*) 1977, 75 pgs
CP/M BIOS Manual ref 2.27, 3/82 by Centra Systems 54 pgs
CP/M 2.2 preface by N*, #25045A, 46 pgs
Additional Northstar related manuals, 2006
InfoSoft NS BASIC double density Program Interface manual, 25 pgs
HDS Hybrid Development System by Allen Ashley, 1979, 32 pgs
Northstar "addendum" for various manuals:
System Software Manual Rev 2.1 July 1980, source, 14 pgs
System Software Manual Rev 1 Dec 1978, incomplete. 4 pgs.
Northstar User Group NSUG newsletter/magazine "The Compass"
Vol I, #1, 24 pgs
Vol I, #2, 24 pgs
Vol I, #3 38 pgs
Vol I, #4 42 pgs
Vol II, #1, 46 pgs (copy)
Vol II, #2, 44 pgs
Vol II #3, 40 pgs
Vol II, #4, 40 pgs
Vol III #1 34 pgs
Vol III #3, 60 pgs
Vol IV #1, 36 pgs
Vol IV special 10 pgs
Herb Johnson
Copyright © 2007 Herb Johnson