The 4 kB ROM normally contained "Screenware Pak I", which provided routines to emulate an 85 by 40 line character screen, which also allowed the user to define their own 12 by 6 pixel character sets in the card's RAM. The screen buffer could be moved to or from the computer's main memory - useful for printing when pushed from the card to the computer, or displaying bitmap graphics when reversed. The data sent over the bus was examined by the Z80 on the card, which then ran a selected subroutine contained in its ROM to place data into the frame buffer. Users programmed the MicroAngelo in assembly language using the Z80's input/output parallel ports, which sent data over the internal S-100 bus at relatively high speeds. The original MA512 board included 32 kB of RAM for the frame buffer, a Z80 processor operating as a controller and memory refresh driver, and 4 kB of ROM containing one of two optional sets of subroutines. Early versions of AutoCAD supported the MicroAngelo system. The MicroAngelo Palette (or Colour Mixing) Card used the output of multiple MicroAngelo's as individual bit-planes to produce images with up to 256 colors (using 8 cards). Each MicroAngelo board produced a 512 by 480 pixel monochrome image, high resolution for the era. SCION's MicroAngelo was an early graphics card for S-100 bus computers. Not to be confused with Microangelo Toolset.
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