10 Aug
2012
10 Aug
'12
10:10 a.m.
On 8/10/12 5:58 AM, Andrew Lynch wrote:
Hi
Does anyone know of an X Window server implementation for the NEC 7220 GDC?
The chip has several names including the Intel 82720, NEC 7220A, NEC 7220D,
uPD7220, uPD72020, etc. Essentially this graphics chip was the main rival
to the MC6845 prior to the domination of the IBM PC architecture for
microcomputers.
The 7220 and 6845 are quite different. The 6845 is pretty much just a timing
generator, the 7220 is a microcoded graphics processor. The problem you'll have
with putting a window system on a 7220 is the same one that SGI had with the
68000 IRIS frame buffers. Neither is really designed for direct access to the
framebuffer. Both assumed the graphics model was geometry, and not rasterops.
You'll be better off with some flavor of VGA (hopefully with an extended flat
pixel addressing space) with the processor talking directly to it, and not try
to use an 80's era drawing processor.
--Al (been there, done that at AED with an AMD QPDM)