On Thu, 5 Aug 1999, Bo Zimmerman wrote:
>
> The Commodore SuperPET SP9000 -- Wow, there are not one, but TWO revisions
> of the SP9000 expansion board. The older is a double expansion board,
> feeding off the main power supply directly, having 16 or so memory chips to
> make up the 64K expansion, and actually double-deckered over the main board.
> The newer (the one I use) is a single integrated expansion board drawing
> power from the little 5 pin port near the back of the main board, and having
> only 8 memory chips. This stuff is merely amusing, but not perplexing.
>
> What I don't understand though, is the last difference between them.
> The older board had, mounted on the right hand side, a second pair of
> switches in addition to the standard "Read/RW/Prog" and "6502/6509/Prog"
> switches. These other switches were two-position instead of three, and one
> was marked "RAM/ROM" and the other was marked with the name of a chip
> socket, and something like "disable, enable". These switches were attached
> in two places. One was to a pair of chips in the expansion sockets of the
> main board. The other was to an extra 3 pin port on the lower of the two
> expansion board (one not present on newer version). Can someone with an
> older superPET tell me what this extra pair of switches does? I couldn't
> tell myself because there is apparantly something wrong with the memory on
> the expansion board -- none of the languages would boot, but would lock up
> the computer.
There are 4 switches on my SuperPET(the old version).
1. Read R/W Prog. - This controls access to the 64K expansion memory.
It must be at R/W to run the Waterloo system
2. 6809 6502 Prog. - This controlls access to the processor.
It must be at 6809 to run the Waterloo System.
NOTE: Both switches 1. and 2. are connect by a single 6 pin connector on
the right side of the board.
3. UD11 RAM ROM - This controlls access to $9000-9FFF.
This must be set to RAM for the Waterloo system.
This is actually a double switch. The part
to the outside of the computer controlls the the chip
select line for the ROM by way of an adapter. The part
of the switch towards the inside of the computer
controls RAM access and is connected to the 3 pin
connector at the front of the board.
4. UD12 OFF ON - This controll access to the ROM at UD12($A000-AFFF).
This must be off for the Waterloo system.
It is connected to an adapter in socket UD12.
In addition, there should be a small daughter board in a card edge
connector towards the right rear of the top(memory) board. The chips on
the board should be facing towards the rear of the computer. The Waterloo
software will not load without this board.
The chips in sockets UD11 and UD12 could be anything. Some PET software
required a ROM in these sockets and the switches are a way of turning them
on and off. Also, when SuperPETs were shipped from the factory, they had
ROMs in these sockets. These ROMs had no function that I could find. In
fact, all the ROMs that I saw were actually obselete ROMs, apparently
placed in the sockets for test purposes, and simply left there. Look
carefully at these ROMs. You may have some rare version of an old ROM.
-
This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tcm.hut.fi.
Archive generated by hypermail 2.1.1.