Re: Floating Bus quirks

[kentd@cup.hp.com (Kent Dickey)]

>>> I was reading the October, 1982 issue of SofTalk, wherein Bob Bishop has
>>> a nice little article that starts with a quick little program that
>>> displays text in the upper half of the screen, and graphics in the lower
>>> half.

KEGS does not emulate the floating bus, but does support mid-screen
changes.  Super-hires, lores, hires, and text on one screen is
no problem.  Multicolor text works great too.  (Due to laziness on
my part, switching happens only every 8 screen lines, but this could
be fixed pretty easily).

The problem with the floating bus is you don't know whether code
reading $c051 or $c050 (for instance) needs to get the floating data
or if it's just trying to switch graphics modes.  KEGS could
calculate the correct floating data, but then everything would be
slower since lots of code is reading locations which "float" all
the time.  I decided not to do it since the only thing
I knew that relied on the floating bus was Bob Bishop's demo program
which has no real value (other than gee-whiz factor).  I could
add it as a feature if people wanted it, though.

Supporting this has nothing to do with your PC's refresh rate.
It's also pretty easy.

KEGS, with full source code, is available at:
http://www.crosswinds.net/san-jose/~kentd/kegs/

No Windows port is available (yet), but KEGS works on Linux, HP-UX, Solaris,
and OS/2.

Kent