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A92: Plans for porting Fargo to the 92 Plus (and possibly the 89 as well)
I started writing this as a reply to a message on ti-hardware, then I
realized that it was off-topic. So I decided to post it here:
I plan on porting Fargo to the TI-92 Plus. Programs will almost certainly
*not* need to be rewritten. Even if the RAM addresses change drastically,
I'll be able to make a program converter that will adapt old Fargo II
programs to work with the new TI-92 Plus compatible Fargo. In fact I have
been planning for this contingency, which is why I require (and allow)
Fargo II programs to use the base address of LCD RAM (tios::globals) as a
base address to which offsets may be added, yielding pointers to various
RAM globals. The alternative would have been putting a separate entry in
the tios table for each and every global variable, and that idea did not
appeal to me at all.
Warning -- NEVER do something like this:
lea tios::kb_globals,a2 ; get base address of keyboard globals
... ; code that doesn't modify A2
move.w $C(a2),d0 ; get current keyboard "scancode"
ALWAYS do this instead:
move.w tios::kb_globals+$C,d0
Note that the same rule applies to tios::globals!
This is very important, because it places an entry in the relocation table
(actually the import table) for every reference to a potentially
ROM-specific address. This will make it easy for me to write a conversion
program if the need arises. Probably what will happen is that I will divide
the block of globals referred to by tios::globals into several pieces,
making sure they are contiguous on the 92+ as well as previous ROM
versions. I'm hoping there won't need to be very many pieces. (Actually I'm
hoping there won't be a need for a conversion program at all.)
I am tentatively considering the idea of porting Fargo to the TI-89. Of
course, in order to be able to seriously consider this idea (let alone plan
it), I'll need a lot more information on the 89 than is currently
available. And it also depends on whether or not I decide to buy an 89.
(Note that I will buy the 92 Plus immediately after it hits the market, no
questions asked. The TI-89, on the other hand, is a horse of a different
color. I *may* buy it.)
---
David Ellsworth
davidell@earthling.net
IRC: eXocomp
ICQ: 2300673