23 Feb
2009
23 Feb
'09
3:26 a.m.
On Sun, 22 Feb 2009, Josh Dersch wrote:
Richard wrote:
We have several third-party ROM and RAM modules for our 4051. A RAM module
(called BACKRAM) behaves like a ROM module after you have loaded the
contents from tape. There is one module with support for CBM drives,
special I/O routines, assembler and firmware routines.
The documentation (alas German only) for these ROMs can be found at
ftp.informatik.uni-stuttgart.de/pub/cm/tek4051/
BTW it *is* possible to write 6800 programs, it's just not officially
documented. The magic command is
CALL "exec" [,{Var1} [,{Var2} {,...]]], {Loaderstring}
(see exec.txt and ram_loader.prg)
I guess the best way to get data transferred from
these systems is to
use the GPIB interface and transfer the programs out of the system and
into the internet. I wonder if the easiest would be to use a
Commodore GPIB compatable floppy drive or something.
Or over the optional RS-232 expansion (at a whopping 2400bps). I've been
experimenting with this idea for archiving 405x tapes (and Bob Rosenbloom has
offered to lend me a couple of tapes to play with) but the major catch is
that the 4051 appears to _only_ be programmable in BASIC -- there's no
PEEK/POKE or ways to call user 6800 machine code. This wouldn't be a problem
except that it's possible to protect tape files with the "SECRET" command
--
this makes a given file execute-only, so it appears to be impossible to read
the contents of the file using BASIC commands. I'm guessing that most (if
not all) commercial software tapes are protected in such a manner, but I
suppose I'll find out. I'm looking into whether if it's possible to
adapt one of the "backpack"
expansions to take EPROMs instead of MCM6832 ROMs. Anyone done this before?
Given a bit of hacking it'd then be possible to write some 6800 code to do a
binary dump of the tapes, bypassing the protection mechanisms.
I've already written a little BASIC program that uses the special ROM
functions in order to create real tape dumps into a CBM floppy file. These
dumps contain all records etc., and it is possible to create a real tape
from that image. The commands are TREAD and TWRITE.
The file sysrom.txt contains a descriptions of the system ROM entry points
and the function they perform.
And here's how to un-secret a program (see exec.txt):
L$="7?008039"
CALL "exec",L$
Christian