The "motion vector" displays that were generated for Battlestar
Galactica were not
done on the 4051. They were done on the Tektronix 4081, which was a
very interesting machine.
19" DVST (Direct View Storage Tube) for the display, which had a mode
which was called "write-thru" which allowed the beam to run at a reduced
intensity which would cause line segments
not to 'store'. If the beam was moved around fast enough, you could do
moving vectors.
The 4081 was based on an OEM'd Interdata 7/16 CPU board. As I recall,
the Interdata 7/16
had an IBM 360-like instruction set. It was a 16-bit CPU, made to run
with core memory
(thus it had a write-sense-rewrite memory cycle). Tektronix designed a
specialized
display processor, which would share main memory with the CPU, and
operated on "display lists".
The display processor was fast enough that it could draw vector graphics
in write-thru
mode fast enough that (if there weren't too many segments) you could do
some pretty good animations without flicker. As I recall, the display
processor was reasonably smart...allowing a series of vectors to be
'connected' together as an entity, and all that was necessary to move it
around was to update the display list parameters that stated the origin
of the object, e.g., early sprites.
The 4081 CPU cabinet was about the size of one of those small
refrigerators that you can put under a desk. The systems booted (IPL'd)
off a mag-tape cartridge, the same type as used on the 4051. The 4081
generally came with at least one cartridge disk drive (ala DEC RK05, but
made by CDC
as I recall) with one fixed, and one removable cartridge platter, each
of about 5 Megabytes.
There was an operating system for the machine, but I can't remember for
the life of me what
it was called. Most of the programming was done in a macro assembler,
though I think that
there was a FORTRAN complier also available for the machine, along with
PLOT 10 libraries.
Tektronix graphics programmers worked with the producers of the show to
generate the vector
animation graphics on the 4081.
There *was* a modification that some folks did to the 4051 which allowed
it to also do write-thru
animation, but the only way to get anything useful was to write machine
code (4051 BASIC had a means to fill a character string with machine
code and execute it) to run the display system.
With tightly written code (the 4051 used a Motorola 6800 CPU), it was
possible to do some
simple animations without too much flicker. I once saw a "space war"
style game run
on such a modified 4051, and it wasn't bad at all. The later 4052 and
4054 machines, with their biploar implementations of the 6800
instruction set, I believe had a 'write thru' mode to allow vector
graphic animation to be done without having to do hardware
modifications.
I know all of this because I worked at Tektronix at the time, and did a
lot of programming on the 4081 and 4051. I remember a big story in
'Tekweek' (Tektronix' internal company newspaper)
about Tektronix contributing so heavily to the production of Battlestar
Galactica. Not only
were a lot of 4051's used, they also used a lot of TM500 modular test
equipment on the set.
Rick Bensene
Tektronix employee - 1977-1990
The Old Calculator Web Museum
http://oldcalculatormuseum.com
Received on Fri Mar 28 2003 - 23:25:00 GMT