8 Jul
1999
8 Jul
'99
1:41 p.m.
Many 8K static memory boards had provision for battery
backup.
Some cards used S100 pin 14 for this. These diodes were to feed
the battery voltage to the VR outputs. They are not required if
you are not using a backup battery with this card.
Yup! That's just how they are wired. Now, I've just put it back
in, and the behavior has changed! I still can't DEPOSIT anything,
however there does now seem to be data in the card. It's in an
interesting pattern (excuse the C syntax):
if (address == 0x0000)
data = 0xCF;
else if (address & 0x0200)
{
if (address & 0x0002)
data = 0x00;
else
data = 0xFF;
}
else
{
if (address & 0x0002)
data = 0xFF;
else
data = 0x00;
}
Do static RAMs just power up with random data or does this indicate
some kind of crossover between the address and data lines?
Thanks,
Bill