Good news today! I just got the MLDL really working with MLDL capabilities. The WROM instruction is now correctly recognized. There was a very nasty little bug outside my state machine, and it turned out that the WROM instruction has been working all the time. Just reading the data back from MLDL SRAM failed.
For those interested: The MLDL I now created has one 4K page of SRAM at $E000. I have used an Eramco ROMBOX with several Eproms to test writing and reading individual words in the SRAM with the DAVID ASSEMBLER. Second test was to copy the ERAMCO ESMLDL-OS Eprom contents into page $E000 with the COPYROM instruction that is in ESMLDL-OS. Unplugging the ROMBOX left my good old HP41C (2* speedup) with only the RAM connected, and CAT 2 showed the copied ESMLDL-OS! My other machine, a non-speeded HP41CX, showed the same behaviour.
I will put some pictures I have just taken of the prototype on my website, but that could take a few days. Will let you all know when they are online.
Next step is to test the prototype with FLASH and multiple RAM pages. This requires to load larger amounts of data into memory, and I need the external I/O interface for that. The hardware is pretty simple but I need to do some software programming on the PC to be able to bit-bang the control signals of the external interface of the MLDL.
Meindert