>I just thought I'd drop a note, telling the list that I've fixed the bugs
>in the BMVIEW program, and made some minor changes to the layout of the
>code.
Cool!
>And now I have a quick question for the list - does anyone know for
>certain, what is the sequence of writes which enables the Backup RAM, and
>what disables it ?
To enable the RAM it's:
lda #$80
sta $1807
And to disable it it's:
lda $1803
And apparently a 'csl' is also needed when accessing the Backup RAM,
it must be a slow RAM or something like that.
>I seem to recall that enabling is succesive writes to $1407 - 3 specific
>bytes, I think ?
Hmm strange, that sounds familiar, I already heard of this 3 bytes
sequence, but I can't remember where...
The code above is what they use in the System Card.
>I am asking, because I have been playing with my Develo box lately, and
>found that reading segment $F7 yields only a series of bytes equivalent to
>the MSB of the address lines...
Very interesting!
>(I wonder if I can format a Develo-style MX file to download to the
>machine, to unlock the RAM...)
Should be easy. :)
David