On Jun 6, 2018, at 5:17 PM, Jim Manley via cctalk
<cctalk at classiccmp.org> wrote:
...
I'm one of the early senior docents at the Computer History Museum in
SillyCon Valley and yammered on endlessly about the 6600 and its neighbor,
the 7600, but I never thought about character generation on the displays
beyond it being vector-based drawing. I'm pretty sure it was done via
look-up tables that directed the beams along vectors on the displays for
the operating PDP-1 we play Spacewar!
The crazy thing about the 6000 series display controller is that it doesn't use tables
at all. The selection of what stroke step to produce for a given character and point in
time is defined by a very large collection of gates. The 170 controller does use table
lookup (a ROM with the equivalent information). I wonder why a ROM wasn't used in the
6000. Perhaps they couldn't find a cost-effective technology that's fast enough?
Core rope would work just fine for this, but not at 100 ns cycle time.
paul