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Battery backed 32k Ram

Posted: Thu Mar 26, 2020 7:29 pm
by janvb
With 32k sram installed i no longer use my atom diskdrive at this moment.
For loading programs i use parallel port and an arduino uno.
But for this to work, i first got to load a machinecode program into the atom.
Do this now by cassette input. Wav file on windows PC. Gets a bit boring now to do it again and again.
:idea: To have this program non volatile in memory i have 2 options, ROM or since i have 32k Sram in a single chip a battery :D .
SRAM connected to Battery.jpg
You can see the wires, red and black connected to the W24512 IC.
Inside Atom.jpg
Did some test, and yes it works… but not always, had to connect a resistor to Vcc and CE to make it work proper.
At first had a regulated power supply connected to the chip. Was very curious how low i could drop the voltage.
Did go as low as 3V and then got an error and worce a randomised screen :oops: :oops: :oops: :oops:
I thought , "GLOEIENDE GLOEIENDE NONDEJU" what have i done now ?? (cursing in dutch).

But finaly found the oops, it didn't have anything to do with supply, but was an accidental coincidence.
To make a long story short, there is a chip beneath the RAM board, IC23, wich seemes to have bad contacts.
This explains also the weird graphics i had some times. (for those who have weird graphic things going on, check this ic).

All works fine now :D :D :D .

Gr.

Jan