ROMWBW and RTC (NVRAM) support on RC EZ80 system

[Richard Deane]

Hi,

I've got ROMWBW (github version of yesterday) working nicely on rc2014
to autoboot into cpm3 using nvram and switches

I note however that on RCEZ80 (Dean Netherton's design) RTC is
supported for giving system date but not NVRAM.

I suppose there is an architectural reason for this and would love an
explanation.


Cheers
Richard

[Wayne Warthen]

Hi Richard,

Dean would know better, but I don't think the eZ80 has NVRAM, just an RTC.

Thanks, Wayne

[Bill McMullen]

That's correct Wayne, there isn't NVRAM.  The eZ80F92 has an RTC with 1 second resolution, 8KB of SRAM and 128KB + 256B of flash memory.

[Richard Deane]

Thanks,

I was hoping the ez80 would emulate the necessary nvram given there is
some flash ram. Too optimistic I guess.
Richard

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[Dean Netherton]

Hi,

Travelling at the moment - typing on phone. Sorry for typos

I had forgotten about that 256 bytes of flash rom. (Was thinking of just using a page in the main 128k rom)

 Would imagine it could be used for the nvram equivalent .

I have and still do, would like to implement some more firmware code to do the low level logic.  Encapsulating the main function, ports etc.

With some ez80 firmware extensions handling the read and write of specific bytes, 

then the hbios driver could be updated to delegate to the firmware (in same way all the ez80 hbios drivers do)

The only thing stopping this is time

  

Happy if others want to make a pr.  

Richard. Please feel free to add an issue to the ez80 GitHub repo

 To request the enhancement 

Cheers

Dean

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[Richard Deane]

No worries, will do.
cheers
Richard