Video Generation
Galaksija did not have a dedicated video circuitry. Inspired by the CDP 1802 application book, its Z80A CPU was directly responsible for modulating the monochrome video signal with a little help of a shift register. Galaksija's CPU would write one byte to the shift register, which would, in turn, serialize its 8 bits one by one to the video output.
Since Galaksija had little RAM, a portion of it was taken not to store information for each pixel separately but character codes. CPU then had to look up character definitions in its character definitions ROM to find the values to send to the shift register.
This was standard operation available in Galaksija's ROM. Some software, however, reportedly took the responsibility for driving the shift register (and thus generating video) and was able to use various tricks to achieve what appears as high-resolution graphics, such as with user defined graphic characters.
It was thus possible for Galaksija with sufficient RAM upgrade (having at least 6144 bytes available for video memory) to achieve 256x208 graphics without any specialized circuitry. Other resolutions were also possible while maintaining only pixel width, by changing the amount of the active area of video picture and/or handling two interlaced video fields separately. Changing the number of active lines would have also altered the CPU usage for video generation and ratio of it available for other use.
Read more about this topic: Galaksija (computer)
Famous quotes containing the words video and/or generation:
“We attempt to remember our collective American childhood, the way it was, but what we often remember is a combination of real past, pieces reshaped by bitterness and love, and, of course, the video pastthe portrayals of family life on such television programs as Leave it to Beaver and Father Knows Best and all the rest.”
—Richard Louv (20th century)
“The pork sizzles and cries for fish. Luckily for the foolish race, and this particularly foolish generation of trout, the night shut down at last, not a little deepened by the dark side of Ktaadn, which, like a permanent shadow, reared itself from the eastern bank.”
—Henry David Thoreau (18171862)