Re: Battery Backed RAM Card

[aiiadict@gmail.com]

>Mind you, even if you did get the RAM to keep its data, you'd have to
>modify it before shutting down the system to get the processor into
>the right state to start executing from where it was again.
>Talk about needlessly complex.  :-)


When the Apple II boots, the 6502 jmps to
specific RAM location to start code
execution.

Replace it with small program:

is open-apple pressed?
yes - continue normal boot
no  -  (default state)
       lda PCLO
       PHA
       lda PCHI
       PHA
       load a,x,y status byte
       RTS

and when you turn computer
off with RAM "keeper" in operation:

generate interrupt
save a,x,y, status byte
store PC register in PCLO, PCHI

**********************************************

Rich