[Coco] silly question about ?OM/?FC errors

[Rogelio Perea]

>> Tells BASIC not to reserve any space for pmode graphics
>> screens.  For some of the adventures off the Rainbow Book
>> of Adventures and, you may also need diskoff or diskoff3.
>
> Never heard of these, are they public domain?  Sounds
> interesting.  I've always used Spectrum's 40k disk utility
> which worked a little better than the "pclear 0" pokes,
> but some things still ran out of memory.

DISKOFF and DISKOFF3 were two utilities published in The Rainbow (I believe 
written by Jeremy Spiller, am I way-off here?). The first one is intended 
for use in the CoCo 1/2 and the later in the CoCo 3 (hence the obvious '3' 
there). What these did is that they allowed you to LOAD those particularly 
long ECB programs intended for use on cassette only systems and because of 
their size they wouldn't run under Disk ECB - remember that the disk system 
takes away at east 2k more of RAM when active, 2k that might as well be used 
by a Basic program.

The routines load normally from DECB and then prompt you for a filename, 
which is the one from the .BAS program with the "problem", the drives begin 
to spin and the system will load the program into memory and then the magic 
starts to happen: without loosing the program already in the code buffer, 
the CoCo rearranges memory so the DECB extensions go away, the CoCo system 
will "think" it's running under plain cassette ECB (no disk attached) and 
after a couple more RAM blocks re-arrangement the Basic program starts 
running. To regain DECB the CoCo needs to be cold started.

I know that these utilities were pretty handy mostly for long text adventure 
programs.


-=[ Rogelio ]=-