Re: Upgrading the Apple][ to //e

[dempson@actrix.gen.nz (David Empson)]

Robert Steinmetz <not-rsteinmetz@mindspring.com> wrote:

> I have my original Apple][ and for a long time when I used it 
> every day I was able to keep it up with all of the current 
> technology I needed. I eventually moved to a //c and a Laser 128.
> 
> 
> I am wonder how close I can get i to compliance with a //e.

[Details snipped]

> What steps can I take to make this machine more compatible with 
> the //e?

It sounds like you've already done everything that is feasible.

Software which requires a IIe may depend on any of the following
features, none of which are available in a ][ or ][+, due to lack of
hardware support:

- Auxiliary memory (128K, with bank switching in several regions and
lots of associated soft switches).  A large memory card in a standard
slot can't simulate the bank switching technique, so the best you can
get is a data storage facility or a multi-bank language card.  Some
applications can use these sorts of cards for additional data storage,
but anything which requires a "128K IIe" is unlikely to work.

- IIe hardware-compatible and/or 80-column text display.  This is tied
into the auxiliary memory mechanism.  An 80-column card in slot 3 will
be compatible with a fair amount of software, but some may depend on
specific features of the IIe 80-column firmware or hardware.

- Double hi-res graphics mode.  Also tied into the auxiliary memory
hardware.

- Double lo-res graphics mode.  Also tied into the auxiliary memory
hardware.  Not used very often, and doesn't have firmware support in the
IIe, but can be used by applications which have their own display
driver.

- Alternate character set, including inverse lower case, plus MouseText
on an enhanced IIe.  This is only a cosmetic display issue.

With the enhanced IIe, there are also some firmware features that are
missing from the ][/][+, including the mini-assembler and enhanced
interrupt support.

There are some other minor details, such as the self-test code in the
$C100-$C7FF area, and the different behaviour of RESET (][/][+ language
card remains selected after reset, but the IIe always switches to
motherboard ROM).

-- 
David Empson
dempson@actrix.gen.nz