movie computers (The List! )

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(a)eng.cam.ac.uk The gates in my computer are AND,OR and NOT, not Bill