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May 22nd, 2010, 03:35 PM
Professional Graphics Controller
The IBM Professional Graphics Controller (sometimes called Professional Graphics Adapter or Professional Graphics Array) was, being released in 1984, one of the very first graphics options for the IBM PC to have 2D/3D hardware acceleration. The PGC consisted of two full length cards and one half length card, bolted together like a sandwich. The PGC takes up two ajacent 8-bit ISA slots with spacing based on the PC/XT, so the card can not be used with the original IBM 5150 PC. The card was intended for CAD (Computer Aided Design), and a PGC with matching monitor was priced at about $4500 USD (of 1984 currency).
Natively, the PGC only supports the resolution of 640*480 pixels with a palette of 256 colours (selectable from a total of 4096). If jumper W1 is altered, CGA emulation is enabled, but all the pixels in med-res mode are quartopled in size, making up the resolution of 640*400 (pixels in high-res mode are just doubled to make the same resolution).
The core of the card is the 8088-2 CPU running at 8MHz, it reads commands and data from the input buffer and writes graphic data to the framebuffer. In addition, it also handles the settings for the hardware acceleration. For the hosting computer to do anything with the PGC, it sends commands to the card's input buffer/control area, which is mapped in the memroy map of the host computer. Those commands are processed by the 8088-2, in either ASCII or HEX mode. There is no other way for the host PC to control the PGC.
The PGC was made untill 1987, but due to it's high price and slow graphics processing, it was never an option for the mass-market, EGA was more appealing there. This was not strange since IBM never intended the PGC for the mass-market after all.
The PGC outputs with either 640*480, or 640*400 resolution at 4-bit RGB. The interface is just the same as 9-pin VGA, with the only difference that the PCG uses composite sync instead of H/V sync. Despite this, most VGA monitors will be able to understand the signals from the PGC when a 9-to-15 pin VGA cable is used.
Category:ISA cards