[Simh] An idea for graphics support in SIMH

[Brian Knittel]

This seems like a good approach. Besides the PDP-1, the PDP-11 had the 
VT-11 and the IBM 1130 had the 2250. These are very similar devices -- 
asynchronous display-list vector display processors. Who knows -- maybe 
someone can rig up an Evans and Sutherland PS2 for the PDP-11/70. (I 
think Tom Ferrin's UNIX V6 drivers are available?).  

The approach would also work well for machines with pixel- and 
character-based graphics like the IBM 5100 and 5110. (I have a SIMH 
emulator working, but it's Windows-only at this point due to the 
graphics issue). Then there are the e.g. Cromemco-type boards for the 
Altair, and so on.   

It does sort of open a Pandora's Box though, as it invites the 
proliferation of GUI control panels and other fluff. (Says the author 
of a fluffy, hacked-up GUI control panel for SIMH IBM 1130). One thing 
I like about SIMH is that the experience is all about the software, 
rather than on reproducing the physical appearance of the hardware.  

The tricky part would be the asynchronous nature of these display 
beasts. Could it be done without using a separate thread? Maybe. Or 
could we work up an abstraction of a display thread that was cross-
platform and not too ugly? Maybe. It seems to me that this is where the 
difficulty and elegance will lie.  

Brian