[net.micro] TI99/4A Assistance

nessus@nsc.UUCP (10/11/83)

     Does anyone out there know how the TI99/4A organizes its VDP RAM?  When I
run a rather large program, the first time I try to access the screen using a
user-defined display character the computer gives me a "MEMORY FULL" error
message.  The sequence of operations is this:

	...	...
	1000	CALL CHAR(112"[character definition code]")
	...	...
	2000	CALL HCHAR(10,8,112)
	[at this point the computer goes back to monitor/interpreter(?) and
	says:
	MEMORY FULL AT 2000

     I would like to know what causes this to happen.  The program is smaller
than it was before, yet the computer says "MEMORY FULL".  

     Also, I need some info on how the 9918A Video chip operates.  If anyone can
mail me info on how to access the chip, how to use it, and so on, it would be
appreciated.

					Kchula-Rrit

				menlo70!nsc!nessus

shacklet@ittral.UUCP (Cliff Shackelton) (10/13/83)

As far as I can tell, any user defined characters use **A LOT** of 
memory. All of the RAM in the '99 is connected to the VDG and I think
that this has something to do with it. One possible fix is don't load
your cassette on top of another program. Clear the unit by hitting
"QUIT" and load it into an empty RAM. Data on the VDG is available
from TI in the form of a data book, as it is a standard over the 
counter part. TI semiconductor dealers should be able to supply both
the data book and the part.