Re: Apple /// Information Site

[mdj <mdj.mdj@gmail.com>]

On Jun 25, 7:26 pm, a23 <a...@base10.net> wrote:
> www.apple3.org

Thankyou for this... I had long wondered how the memory organisation
of the Apple /// worked, now I know :-)

Quite, umm, wacky, actually. The bank switching is less sophisticated
than I thought (I prefer the Apple IIe/IIc approach), but I admit I'm
quite taken with the "Extended Indirect Addressing".

For those that don't know, the Apple /// supports an extension on top
of standard 6502 indirect index addressing mode, allowing a bank
specification in a third byte, which permits you to reference any
location in the (possible) 512k of memory, at least for data. JMP's
and JSR's to different banks have to work via a bank select register,
somewhat similar to doing an XFER on the IIe/IIc.

Still, it's nice to finally understand the hardware model after all
these years :-)

Matt