[comp.sys.handhelds] HP48SX memory cards

nisse@milou.cd.chalmers.se (Nils Andersson) (06/10/90)

There has been a discussion about if standard epson cards may be used with the
HP48SX or not. The main problem seems to be the voltage in the HP48SX, which
is a little bit to low for errorfree use of standard cards. When the voltage
gets too low the address pins will be connected to ground. This is correct
according to the data sheet for the cards, but there is another pin of interest.
This pin is output from the card and tell whether the incoming voltage is ok or
not. If it is ok the output will bee a logical one, else zero. The question is
now if HP48SX does not use this information when it tries to read/write the
RAM card. It seems odd to me if the engineers at HP didn't use this, 
but I wouldn't mind getting a good answer to this question!

Nils Andersson
nisse@cd.chalmers.se