[comp.sys.apple2] PUSHing to bank $E1

mquinn@pro-gsplus.cts.com (Michael Quinn) (08/23/90)

I've heard people talking about pushing to SHR Ram (bank $E1).  How is this
possible?  I thought you could ONLY have a stack in bank $00... even with
shadowing, this would only go to bank $E0, not $E1.  Is there something I've
missed?
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toddpw@tybalt.caltech.edu (Todd P. Whitesel) (08/24/90)

mquinn@pro-gsplus.cts.com (Michael Quinn) writes:

>I've heard people talking about pushing to SHR Ram (bank $E1).  How is this
>possible?  I thought you could ONLY have a stack in bank $00... even with
>shadowing, this would only go to bank $E0, not $E1.  Is there something I've
>missed?

Yes -- auxiliary memory. You can flip a switch to make bank $00 writes (or
reads, you can control them seperately) go to bank $01.

Add shadowing of the SHR buffer in bank $01 and you get stack/dp writes going
to $01 and $E1.

Todd Whitesel
toddpw @ tybalt.caltech.edu

jwana@pro-harvest.cts.com (John Wana) (08/25/90)

In-Reply-To: message from mquinn@pro-gsplus.cts.com

What you do is use shadowing so that you can put all of your graphics data
onto bank $01 and then you can change the stack pointer to go to bank $01.

To turn on shadowing to page $01 do this:

        lda     $e0c035
        and     #$f7
        sta     $e0c035

umm....i don't have the source to turning on the stack pointer to $01
memorized but if you want, you can mail me or post and i'll put up the code
for putting the stack pointer to $01

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