VS3100 M76 SPX Video


Video  board  switch gang 
(underneath the hard drive facing the machine's front panel.)
             |
 ____________|___________________________   
|            |                           |         
|------------|---------------------------| 
|        |   |   |__________|  __________|
| P/S    |   | o    o         |          |
|        |   |                |  SCSI    |     
|        |   |  hdd1 area     |  fdd     |
|        |   |                |  i/f     |  
|        |   | o    o         |  area    |
|        |  \|/o    o         |          |
|        |   #                |__________|
|        |      hdd2 area     ___________|
|        |                   |           |
|        |     o    o        |  fdd      |
|        |                   |  area     |
|        |                   |           |
|        |                   |           |
|        |                   |           |
------------------------------------------ 

     (left side of case)
  _____     /|\
 | O N |     |
 | # # |     |
 | 1 2 |     |
  ~~~~~

Switch    (0=down, 1=up)
      mode    field    color Hfreq Vfreq
1 2                    depth (Khz) (Hz)
_________________________________________________
0 0   GPX  1024 x  800    1    55   60  
0 1   SPX  1280 x 1024    1    70   66
1 0   GPX  1024 x  800    8    55   60
1 1   SPX  1280 x 1024    8    70   66

All modes use EIA-343 video including sync on green    

The  video address layout information that I obtained  was  using 
the  **VMS Installation and Operations VAXstation 2000,  MicroVAX 
2000**   volume   order  number  AA-LB34A-TE.  (kudos   to   Marc 
Malagelada)

Field Layout

0x38000000
|                    0x38000fff
|                    |
V____________________V_____
|<------1024-------->|  /|\
|                    |   |
|                    |   |
|        GPX         |  800
|                    |   |
|____________________|__\|/_

0x38000000
|                    0x38011ff
|                    |
V____________________V_____
|<------1280-------->|  /|\
|                    |   |
|       SPX          |   |
|                    |  1024
|                    |   |
|____________________|__\|/_


Mapping repeats @ 0x38400000, 0x38800000, 0x38c00000

Pixels  are mapped in a progressive manner both horizontally  and 
vertically. There is no interlacing of pixel layout with  respect 
to to memory.

     As  it  stands  now, my system seems to  only  display  full 
intensity  white when 0xff's are written to that area of  memory. 
Any other number will not display any pixels


P.S.A