🚀 go-pugleaf

  I replied by email directly to the person who asked about a
Northstar Advantage, but since there seems to be interest in this
group, I thought I would post a general answer.

  The Northstar Advantage is/was a wonderful computer (my first!)  It
is a Z80 machine with both CP/M and Northstar DOS operating systems
available.  It has 6 (non-standard) expansion slots.  One accessory
adds an 8086 processor, and if added, one can run MSDOS.  The
resulting hybrid is totally IMB incompatable, so only generic MSDOS
programs will run.  Because CP/M never had the rigid hardware
requirements of the IBM clone world, virtually all CP/M programs will
run.  The disks are 5.25" 10 hard sectored "quad density" (360K/disk).
The format is also used on Northstar Horizons (an S100 buss machine).
Really, nothing but a Northstar can read or write to these disks.  All
of the software in the world cannot deal with holes punched in the
disk.  Northstar (R.I.P.) used to carry on a vigorous defense of their
decision to go with hard sectored disks.  They claim to have made the
first 5.25" drive system for microcomputers.  (I am told that the
original name of the company was "Kentucky Fried Computers", but that
the Colonel persuaded them to change.)  Although Northstar is out of
business, there is a company still supporting the line.  They sell
software and hardware, including hard disk expansion kits, etc.

  What makes this machine so neat is the graphics capability (unusual
on CP/M machines) and to a lesser extent, the memory management.  It
has a 640x240 pixel black and green bitmapped screen.  Like the Mac,
everything is graphics, including text.  The address space of the Z80
is increased from the normal 64K to 256K by the addition of address
registers.  64K is mapped as main memory, 20K is mapped into a second
64K chunk as video memory, and up to 8K is mapped into a third 64K
space for rom (4k rom is standard).  64K is unused.  Graphics is
accomplished by writing to video ram.  Graphics subroutines
(accessible from assembly language) are provided with Northstar's CP/M
and with Northstar DOS, graphics are available from BASIC.  Northstar
also sold some business graphics programs.  The DEMO disk had some
really neat graphics displays!  The character set is stored in
rom, along with bootstrap routines.  My Advantage was customized by
the dealer by the addition of an 8k rom containing an alternate
character set which included a set of greek and mathematical
characters useful for scientific writing.

  I believe the main thing which kept the Advantage from being a
raging success is that it came out at the wrong time; just as IBM PCs
took over the world.

  For the interested, there is a comp.sys.northstar newsgroup which at
present is very low traffic.

-David Steffen- (ste...@mbir.bcm.tmc.edu)