Re: Old IIc needs new chipset

[dempson@swell.actrix.gen.nz (David Empson)]

In article <Aug01.194148.51884@acs.ucalgary.ca> sbdocker@acs.ucalgary.ca (Sean Brendan Dockery) writes:
> 
> You can't run files of type SYS from the BASIC prompt *unless* they
> have a ".SYSTEM" extension (at least, this seems to be an unspoken
> rule -- someone correct me if I am wrong).

You stand corrected!  :-)

You can run any SYS file from BASIC.SYSTEM by using the "smart run"
(dash) command, _provided_ it isn't too large.  BASIC attempts to load
the entire SYS file at location $2000, and you'll get a NO BUFFERS
AVAILABLE error if the file would overwrite BASIC.SYSTEM and/or its I/O
buffers (about $9200 if you have no files open).

Thus any SYS file larger than $7200 bytes cannot be launched directly
from BASIC.SYSTEM.

SHRINKIT is much larger than this.  Because of this problem, it is
also supplied with a small pre-loader called SHRINKIT.SYSTEM, which
loads at $2000, relocates itself below $2000, then loads the main
SHRINKIT program (which causes no problems now that BASIC.SYSTEM is
out of the way).

If you're using a program selector such as Birds Better Bye or the
ProDOS 1.9+ selector, then there is no problem launching SHRINKIT
directly.  The SHRINKIT.SYSTEM file is only required if you want to
launch SHRINKIT from BASIC.SYSTEM.


The only thing that is special about a filename ending in .SYSTEM is
that ProDOS can potentially launch it on startup (if it is the first
such file in the directory).
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz                                                
Snail mail: P.O. Box 27-103, Wellington, New Zealand