41CL MMU Backup

[Monte Dalrymple]

(06-01-2020 11:48 PM)twoweims Wrote:  

(06-01-2020 10:48 PM)Monte Dalrymple Wrote:  As in the original HP41, these locations are not readable. The bus stays 3-state for these addresses.

The RAM corresponding to those register addresses is accessible using the NEWT WCMD however (I think, not sure I ever tried it.)

I was able to YPOKE a value into 800800 then YMCPY 800>801 then YPOKE a new value into 801800 then YMCPY 801>800 then YPEEK the changed value from 800800.
So it looks like YPEEK/YPOKE and YMCPY can read and write from this location!

That confirms what I expected. All of these functions use the WCMD instruction.