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View Full Version : fun with TI-74s...



JGardner
July 15th, 2012, 11:01 AM
Default user memory "partition" in a Basicalc is at >4000, aka 0x4000h among the heathen...

>4000 & up is cartridge memory, >3FFF & below is "System" RAM. 8K Cartridge memory
can be appended to system RAM with [ CALL ADDMEM ].

Executing CALL ADDMEM with a 32K cartridge appends 8K - The Basicalc model ignores
the other 24K (which can also be useful, but that's for another day).

To append an entire 32K cartridge a loadable sub-program, MEMADD.SUB must be used.

OK, you already know all that - But what if you don't want to append the entire 32K for some
reason - Possible?

Apparently it is. To reset the partition to (say) >8000, try the following:

1) NEW ALL
2) RUN "100.LOAD.PGM"
3) "100.POKE.SUB"
4) "Q"
5) NEW
6) CALL POKE(8192,127): CALL POKE(84,127): NEW

FRE(0) now indicates 23993 bytes of BASIC-usable RAM., with 16K of the cartridge still
above the "partition".

Seems to work normally here - YMMV, & I'd like to hear about it if it does.

Jack

JGardner
July 17th, 2012, 08:04 AM
Hmm, this revision resets the partition <and> survives cycling power...

NEW ALL
CALL POKE(8192,127): CALL POKE(84,127): CALL POKE(8212,255): NEW

Downloading & running pgms, with PCIF & my homebrew serial PC link, both
works. So far... :)

Jack

acadiel
November 3rd, 2017, 09:27 AM
Hmm, this revision resets the partition <and> survives cycling power...

NEW ALL
CALL POKE(8192,127): CALL POKE(84,127): CALL POKE(8212,255): NEW

Downloading & running pgms, with PCIF & my homebrew serial PC link, both
works. So far... :)

Jack

Hey Jack.

Resurrecting an old thread. Considering soldering a 32K chip to the 74 (with a shut off switch if you want to use the cartridge) to see if I can put 32K in the cartridge space. Have enough knowledge of the board to see how I can put that chip at >4000-BFFF?