From:	IN%"rhialto@polder.ubc.kun.nl"  "Olaf Seibert" 18-JUN-1996 04:25:05.80
> Hm, how is the console mode on the VS/MV2000 implemented anyway?
> A real CPU (and if so, can it be used for anything)? Microcode in the
> normal CPU? Voodoo? Something else?

When a MicroVAX is reset, it begins executing at 0x20040000. The console
mode of the VS2000 is a program sitting in ROM on the motherboard.

Traditionally, the first longword of the ROM is a branch to the start of
code and the second longword (0x20040004) is used to help identify the
system; i.e., given a system with  a MicroVAX II processor (which you
discover by reading the SID IPR), you can read 0x20040004 to find out which
system this is.

BTW, AFAIK the only thing the MV2000/VS2000 jumperr does is set a bit in
a register which tells the OS not to trust the monochrome frame buffer. This
allows DEC to build MV2000s without frame buffers (to lower the cost) or
with mildly defective parts (which would prevent monochrome video from
working).

Roger Ivie
ivie@cc.usu.edu