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

[Robert Gault]

AtariJunkie wrote:
> Ok I admit it I forgot!
> 
> I am testing all of my software and I have a lot of text adventure games
> that give ?OM erro or ?FC errors when running them
> 
> I remember there was always a 'memory clear' command but don't remember it.
> There was something I used to type in to allow enough memory to run these...
> 
> PCLEAR something? or CLEAR something?
> 
> Sometimes PCLEAR 1 before loading the game will work but I think there was a
> number, number or something....
> 
> Help!
> 
> Erik
> 
> 
> 
> 

You have not said whether you are using a disk or tape only Coco system. 
User memory will start at $E00 or $600 depending on the above.

Let's assume a disk system with user memory starting at $E00. Normally 
you can only issue a PCLEAR1 and memory from $E00-$13FF is reserved for 
graphics. However, the address for the start of a Basic program is 
stored at $19-$1A (25-26 decimal) in system memory. If you change this 
from $1401 to $E01, store a $00 at $E00, and issue a NEW command, Basic 
will eliminate the graphics memory.


NEW:PCLEAR1:PRINTMEM
27432
POKE&H19,&H0E:POKE&HE00,0:NEW:PRINTMEM
28968

You have recovered 28968-27432=1536 or $600 bytes of memory that would 
have been used for a page of PMODE graphics. Now even if you have a disk 
system but don't want to use any disk commands, you can ....
POKE&H19,6:POKE&H600,0:NEW:PRINTMEM
31016

Now you have recovered 31016-27432=3584 or $E00 bytes of memory.