[Coco] Programs larger than 32K?

[Arthur Flexser]

Actually, I don't know for sure if the KEY264K used peeks and pokes to
share data between the two banks, and switched via interrupts.  I only know
the program from having skimmed some of its docs a long time ago.  But now
that I think about it, it seems to me that things could also be set up to
allow the two banks to both have access to the same Basic variables and
arrays, by manipulating pointers to the variable space so that they matched
up between the two banks.

Art

On Mon, Jan 21, 2019 at 10:17 PM Arthur Flexser <flexser at fiu.edu> wrote:

> This switching of 32K banks is exactly what the KEY264K program does.
> They had it so you could either run 2 programs independently, each in one
> bank, or have the bank switching controlled by interrupts so that in
> effect, the two programs time-shared with one another and perhaps could
> access common data via peeks and pokes.
>
> Art
>
> On Mon, Jan 21, 2019 at 9:44 PM Robert Gault <robert.gault at att.net> wrote:
>
>> Don't know the name of those programs but take a look at the specs for
>> the SN74LS783 (SAM) chip.
>> You will see that in addition to all RAM and RAM/ROM ($FFDF/$FFDE) you
>> can page switch. With 64k RAM
>> installed, writing to $FFD4 gives (page0) normal 32k RAM, but writing to
>> $FFD5 (page1) and your
>> unused 32k is active. Since page switching leaves the ROM present, you
>> might be able to have Basic
>> programs switch pages and in effect use 64k of RAM.
>>
>> Robert
>>
>> L. Curtis Boyle wrote:
>> > There were some commercial programs that allowed two 32k BASIC programs
>> (after a little ML setup, it kept your ROM’s in the upper 32k, and bank
>> switched two 32k RAM banks in the lower half. Can’t remember the names of
>> them, though, off the top of my head.
>> >
>> > Sent from my iPhone
>>
>>