As I remember there was even a schematic being passed
around to use a
standard composite monitor and split out the keyboard interface.
Well, I certainly posted one a few years back -- for a universal
colour/mono/2-monitor cable. Here it is again...
A universal DEC Rainbow video cable
-----------------------------------
This cable allows almost all possible monitor combinations to be used
with the Rainbow (see below).
Connections :
-------------
Rainbow end (DA15-S)
1 >----------+---------+-- Blue Gnd
9 >-------O---------O-- Blue
2 >----------+---------+-- Green Gnd
10 >-------O---------O-- Green
3 >----------+---------+-- Red Gnd
11 >-------O---------O-- Red
4 >----------+---------+-- Mono Gnd
12 >-------O---------O-- Mono
5 >----+
13 >-+ +------------ Power Gnd
6 >----------+------------ Key Gnd
14 >-------------------- From Key
7 >----------------------- Power 12V
15 >-------------------- To Key
8 >----------------------- Key 12V
Box-mounted connectors :
VR201 (DA15-P)
1 o
9 o
2 o
10 o
3 o
11 o
4 o-----------+--------+--- Mono Gnd
12 o--------O--------O--- Mono
5 o-------+---------------- Power Gnd
13 o |
6 o-------+---------------- Key Gnd
14 o--------------------- From Key
7 o------------------------ Power 12V
15 o--------------------- To Key
8 o------------------------ Key 12V
Monitor BNCs :
Red
( o )--------- Red Gnd
|
+----------- Red
Green
( o )--------- Green Gnd
|
+----------- Green
Blue
( o )--------- Blue Gnd
|
+----------- Blue
Mono
( o )--------- Mono Gnd
|
+----------- Mono
LK201 keyboard (RJ11-- front face view)
-------
| |
----- -----
| |
| |
| |
-- ^ ^ ^ ^--
| | | |
From Key -----+ | | +----- To Key
Key 12V----------+ +-------- Key Gnd
Components :
------------
DA15S socket + hood (to fit Rainbow video connector)
DA15P plug + jackposts (for VR201 connection)
4 off 75 Ohm BNC sockets (for monitor connections). You could use other
connectors, like RCA phono, but BNC are standard.
RJ11 socket, chassis mounting (for LK201 keyboard). Chassis mounting
sockets of this type are very hard to find. I ended up making a bracket
to clamp a PCB-mounting one to the panel
Metal box of a suitable size to hold the above connectors (apart from the
DA15S).
1m cable. At least 4 75 Ohm screened cores and 6 single wires. I used a
'unversal SCART cable' which has 6 75 ohm screened cores (I simply
ignored 2 of them), a 4 way screened cable (I used this for the 4
keyboard connections) and 4 other wires (2 in parallel for each of Power
12V and Power Gnd).
Possible monitor combinations :
-------------------------------
1) VR201 only
This is pretty useless, but you can connect a VR201 mono monitor using
the DEC lead to the DA15P on the box. Connect the LK201 keyboard to
either the VR201 or the RJ11 on the box.
2) Standard composite mono monitor
Connect monitor input to 'mono' BNC on the box. Connect LK201 to the RJ11
on the box. This works just like a VR201, but you can use any monitor
3) VR201 and separate mono graphics monitor
Connect VR201 to DA15P. Connect LK201to either RJ11 on the box or to
VR201. Connect second (composite) monitor to the 'green' BNC. You can use
the dual monitor driver for GSX and have text on the VR201 and graphics on
the second monitor
4) Two composite mono monitors
Connect one to 'mono' BNC, other to 'green' BNC. Connect LK201 to RJ11 on
box. Using the dual monitor driver, you get text on the first monitor and
graphics on the second monitor
5) RGB (sync-on-green) colour monitor (e.g. VR241)
Connect monitor inputs to BNCs as follows :
Red - Red
Green - Mono
Blue - Blue.
Connect LK201 to RJ11 on box. This gives the standard DEC color monitor
connections giving green text and colour graphics using the colour
monitor driver
6) RGB monitor and VR201
Connect VR201 to DA15P on box. Connect LK201 to RJ11 on box. Connect
color monitor as follows
Red - Red
Green - Green
Blue - Blue
This gives separate text and colour graphics displays when used with the
dual monitor driver
7) RGB monitor and composite mono monitor
Connect mono monitor input to 'mono' BNC. Connect LK201 to RJ11. Connect
colour monitor as follows
Red - Red
Green - Green
Blue - Blue
This gives separate text and colour graphics displays when used with the
dual monitor driver
-tony