Re: Language Card

["Stefan Miganowicz" <nrsdpms1@tiac.net>]

How do you access integer basic on the card?


Thanks,
Stefan
David Empson <dempson@actrix.gen.nz> wrote in message
1e04vm4.1wrk3he1fjpq4wN%dempson@actrix.gen.nz">news:1e04vm4.1wrk3he1fjpq4wN%dempson@actrix.gen.nz...
> Ed Hillman <ehillman@erinet.com> wrote:
>
> > On Fri, 22 Oct 1999 19:42:45 -0400, "Stefan Miganowicz"
> > <nrsdpms1@tiac.net> wrote:
> >
> > >What exactly does an Apple Language Card do in an Apple II+?
> >
> > The "langauage card" was orignally intended to hold in an extra 16K of
> > RAM whichever of the two BASIC dialects was not resident in your
> > machine's ROM.
>
> Not exactly.  Its actual purpose (and the reason for the name) is that
> it was supplied with and required by the "Apple II Language System",
> which is better known as Apple II UCSD Pascal.
>
> The ability to have both variants of BASIC available without an
> additional ROM card was an added bonus.
>
> Integer or Applesoft BASIC loaded into the language card only uses 12K,
> leaving 4K unused.  The full 16K is used with Pascal, and most of it is
> also used by the ProDOS kernel.
>
> The card works by switching out the 12K of motherboard ROM, replacing it
> with RAM.  This 12K area is divided into two sub-areas: the first 4K
> (D000-DFFF) has two separate banks of RAM, and the remaining 8K
> (E000-FFFF) is common to both banks.
>
> The language card has soft-switches to independently control read-enable
> and write-enable functions for the RAM, and to select the bank.  In
> total, there are eight soft-switches:
>
> C080    Read language card bank 1, write protected
> C081    Read ROM, write language card bank 1
> C082    Read ROM, language card write protected
> C083    Read/write language card bank 1
> C088    Read language card bank 2, write protected
> C089    Read ROM, write language card bank 2
> C08A    Read ROM, language card write protected
> C08B    Read/write language card bank 2
>
> All of the "write enable" locations (C081, C083, C089 and C08B) require
> two accesses to enable writes (subsequent accesses toggle write enable
> into the opposite state, I think).  Accessing any of the other soft
> switches disables writes.
>
> > Eventually the extra memory on the card was used for other things and
> > the cards began to be known as "16K RAM Cards"/
>
> It is also worth noting that the language card functionality is built
> into the motherboard on the Apple IIe and later machines (there is no
> physical slot 0 any more), and that it is called "bank-switched memory"
> in these machines (which is a very silly name, in my opinion, since it
> isn't the only type of bank switched memory in the IIe).
>
> --
> David Empson
> dempson@actrix.gen.nz
> Snail mail: P O Box 27-103, Wellington, New Zealand