Re: Disk ][ Launcher (was: Late night musings...)

[nathan@visi.com (Nathan Mates)]

In article <Pine.SGI.3.91r.960829090359.18978A-100000@freenet>,
Greg J. Buchner <buchner@freenet.msp.mn.us> wrote:
>Well, I had Swatdisk for a while, but I couldn't find any current
>need for it for me.  I don't need to get anything off of 5.25 images,
>I just want to run stuff off of them, mostly Ultima ///, Ultima V &
>Wings of Fury.  I'm not looking for a desktop //e emulator...what
>I'd be interested in is something like DOS 3.3 Launcher that instead
>of re-routing the DOS 3.3 stuff to ProDOS commands, would route the
>5.25 disk interface calls to ProDOS.

   Problem: 2 of those 3 games you mentioned (U5 and WoF) use 64-128K
of memory. ProDOS wants to also reside in the upper 16K of the first
64K of memory, and if the game stomps over the OS, it can't do any
more disk access. Dos 3.3 Launcher does a great job, for anything
using only the first 48K of memory. If it wants 64K, *CRASH* sooner or
later.

   The essential problem is that most games assumed that they had full
control over the system, and could write anything in memory where they
wanted to. That was true at the time, and games didwell with a reboot
between them. Now, when the OS encourages sharing of system resources
in order to get multiple things loaded at once, the games which are
written in a diametrically opposed manner won't work.

   Is that a surprise that games don't get along with the rest of the
system? The solution is to rewrite those games or the OS. Neither is a
particularly pleasing or easy task. GS/OS and many GS/OS programs share
parts of the first 64K of ram for "direct page" access. That is where
games want exclusive use of ram. Something's got to give.

   Finally, you seem to want to "route the 5.25" disk interface calls
to ProDOS." Dos 3.3 Launcher already does translate RWTS calls so that
sector level access is possible from _anything_that_follows_the_rules_.
You can't really get at any lower level-- you can't really snoop or
even intercept on anything that bangs on the 5.25" disk hardware
directly.

   After all this, you wonder why programmers get testy when anyone
starts trying to throw out the rules. Things may work better for that
one program, but down the road, there will be FAR worse consequences.

Nathan Mates

--
<*> Nathan Mates http://www.visi.com/~nathan/      <*>
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