10 Nov
2005
10 Nov
'05
11:46 a.m.
Here it is with relation to the boardswapper guides:
NP/=MonAck/ --( )-- WrFull/=FLB/
NW/=MonStb --( )-- DD15=GS
Gnd --( )-- MonClrAddr/=NL/
Gnd --( )-- +5V
I6=MD(6) --( )-- +5V
CS=MD(7) --( )-- +5V
I4=MD(4) --( ) N/C
I5=MD(5) --( )-- -Vm
I2=MD(2) --( )-- -Vm
I3=MD(3) --( )-- +Vm
I0=MD(0) --( )-- +Vm
I1=MD(1) --( )-- Gnd
IV=MD(9) --( )-- Gnd
CUR=MD(8) --( )-- MD(12)=RDA
UL=MD(11) --( )-- MD(13)=GRA
B=MD(10) --( )-- MD(14)=BLA
AS=GS/=DA14 --( )-- Gnd
Gnd --( )-- Init/
where
NP = New Page (=> load start address + AS + GS from block 0 at address
600000 into address register
)
NL = New Line (=> read one line from crt buffer
into line buffer)
NW = New Word (=> provide next character+attribute data to monitor)
Well, my names were'd too ridiculous, then, considering I worked them out
before seeing the boardswapper guide.
AS = Alpha Select (=> enable alpha display, used as
GS/ for switching
between alpha and graphics on the monochromes)
GS = Graphics Select (=> enable graphics display on the 9845C only,
where alpha & graphics can be displayed simultaneously)
Are you sure that doesn't also apply to the 98780 enhanced mono monitor?
The text and graphic systems are pretty much seperate on that monitor,
OK, there is one video timing chain (on the text PCB) that provides
timing signals to the graphics board too, but the graphics unit has its
own memory, video shift register, etc. The outputs are combinded by a
fairly complex mixer circuit on the interface PCB in the monitor. There
is no good reason why the 2 can't be displayed at the same time.
Quite interesting the INIT/-signal is looped through
to the monitor.
Well, I guess the ciorcuitry needs the power-on reset, etc.
-tony