[Coco] superpet

[Willard Goosey]

I was browsing through the library today and stumbled across a book
called "Introducing the SuperPET" or someting like that, so I picked
it up and looked through it.

Commodore's SuperPET is a dual processor machine, with a 6502 & a
6809.  The 6809 makes it at least vaguely on topic for this list. :-)
It has several interesting features.

First, it's dual processor is either/or.  There's a hardware switch on
the front to select either 6502, 6809, or enable a software switch for
the two.

The memory map (which is the same for either processor) has 32K RAM
starting at 0x0000.  Above that is video RAM, a 4K bank-switchable
page, I/O space, and ROM.  There is an additional 64K RAM that can be
switched into the switchable page, in 4K blocks.  There are also two
ROMs, and switching the processor automatically selects the proper ROM
and reboots the machine.

Disk drives are connected via IEEE-488.  They are intelligent drives,
handling the filesystem themselves.  

The 6502 ROM is Commodore BASIC.  I read somewhere that the PET line
actually had Microsoft BASIC, but Commodore didn't fess up one way or
the other.

The 6809 ROM is more interesting.  It's a BIOS for a Pascal system
developed at the University of Waterloo.  From the description, it
sounds similar to the old P-code system, except that it compiles down
to 6809 binaries.  It is implied that the Pascal system has to load
more code off a disk to be functional.  

I was hoping the book would mention OS-9, but it didn't. :-(

Willard
-- 
Willard Goosey  goosey at sdc.org
Socorro, New Mexico, USA
I search my heart and find Cimmeria, land of Darkness and the Night.
  -- R.E. Howard