HP48GX RAM card design

[pdo]

Hi Wan,

Nice work!

For the record, the 330 ohm resistors in the data lines were put there to limit the current flow in case of contention between the processor and RAM chip. i.e. if something was very wrong in the control or timing of the chip and the processor and RAM were both trying to drive opposite levels onto the data lines at the same time.

An abundance of caution, you might say, because I had no proper specification for the processor chip and didn't want to damage it if my design was wrong.

Paul