>
>
> I asked a friend of mine who worked for the company that did the graphics
> for Starfighter about the computers used in the process.
>
> Her reply was as follows:
>
> > They were done on a Ramtek 2020, with the images stored and
> > manipulated using a VAX mainframe. There were a number of things
> > that people thought were models which were really images done with
> > the Ramtek.
I'm not familiar with that model of Ramtek, but I can talk about a couple
of related things that may be of interest.
The first is that Ramtek also made lower-end (and I guess cheaper) units,
like the RM-9460. This used a 68000 as the main CPU, along with a couple
of Z80's for I/O (serial port handling,etc) and some AMD2900 stuff for
panning/zooming/window control. The basic design was roughly what you'd
expect.
A more interesting machine was the I2S model 70 series. I2S are/were
International Imaging Systems, who split off (?) from Stanford Technology
Corp. The model 70 was a work of art. The basic idea was a 'byteplane' - a
raster-scanned area of memory with one byte per pixel. There were a number
of these (6-12 was typical), and the outputs of each one went to 3 look up
tables, which defined the RGB values for each of the 256 possible bytes.
The outputs of all 'Red' lookup tables were then added together (there was
a 14-input full adder board!), and the output of that went to another
lookup table, and then to a DAC. Repeat all that for the other 2 colours.
So far I've described an interesting graphics display, but there was more.
There was a thing called the 'feedback ALU' which used 2 of the byteplanes
as a 16 bit accumulator. You defined a region on the screen (using a
bitplane - this region did not have to be rectangular, or even
contiguous), and then defined a function (one of the standard ones
provided by the 74181 ALU chip) to be used inside the region, and a
different one outside. The thing then performed the function between the
displayed image (I _think_ one colour at a time) and the accumulator, and
put the result in the accumulator. Oh, you could shift the byteplanes
arround, so that you could combine the values from neighbouring pixels.
There was also a programable cursor (trackball or tablet-controlled), a
histogram board, and even (on some model 75's) a hardware sequencer board
(using a 2910 and some RAM) that would run a sequence of operations again
and again.
I don't know if one was ever used for the special effects in a film, but
I'm almost _sure_ one was used to process the weather satellite pictures
for the BBC television broadcasts in the UK.
Oh, and if you think minicomputers are complex, try one of these. Some
early model 70's used 4K DRAMs for the byteplanes. There were typically
3-6 _thousand_ RAM chips, along with a lot of TTL logic....
--
-tony
ard12_at_eng.cam.ac.uk
The gates in my computer are AND,OR and NOT, not Bill
Received on Wed May 07 1997 - 19:06:19 BST