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M7602/VCB01/QVSS interface information

J

jmdhuse

Experienced Member
Joined
Apr 30, 2022
Messages
270
Location
USA - Arizona
Hello All,

I've been starting to mess around with MicroVAX stuff lately, and I got my hands on the monochrome display board used in many of the VAXStation configurations: M7602/VCB01/QVSS. I wasn't able to find any documentation on the 20-pin IDC connector that ideally would go to a patch panel that provides the interface for the monitor, keyboard, and mouse/tablet. So, I spent some time tracing out circuits and believe I have determined all the pin definitions. Here they are, for anyone to use (or to correct!!!):

1 GND
2 +12V
3 RXD_KEYBOARD (4800 baud)
4 TXD_KEYBOARD
5 GND
6 -12V
7 RXD_TABLET (4800 baud)
8 TXD_TABLET
9 HSYNC
10 MOUSE_Y_COUNT
11 MOUSE_X_COUNT
12 VIDEO
13 MOUSE_Y_UP/DOWN
14 MOUSE_X_UP/DOWN
15 MOUSE_BUTTON_1
16 VSYNC
17 +5V
18 MOUSE_BUTTON_2
19 MOUSE_BUTTON_3
20 GND

All the signals are TTL-level, except for the keyboard and tablet, which use RS-232 (+/-12V, inverted logic) signaling. Also, I might have X and Y on the mouse backwards, and I am not sure of the actual mouse button numbering. I don't have a keyboard or mouse in my possession, but I figure this would be useful for anyone (including me) who might try to emulate them with more modern hardware.

Cheers, Jon.
 
jmdhuse said:
Hello All,

So, I spent some time tracing out circuits and believe I have determined all the pin definitions. Here they are, for anyone to use (or to correct!!!):
Click to expand...
I'm just starting to experiment with this board, and this will save me some trouble. Thanks!
 
jmdhuse said:
Hello All,

I've been starting to mess around with MicroVAX stuff lately, and I got my hands on the monochrome display board used in many of the VAXStation configurations: M7602/VCB01/QVSS. I wasn't able to find any documentation on the 20-pin IDC connector that ideally would go to a patch panel that provides the interface for the monitor, keyboard, and mouse/tablet. So, I spent some time tracing out circuits and believe I have determined all the pin definitions. Here they are, for anyone to use (or to correct!!!):

1 GND
2 +12V
3 RXD_KEYBOARD (4800 baud)
4 TXD_KEYBOARD
5 GND
6 -12V
7 RXD_TABLET (4800 baud)
8 TXD_TABLET
9 HSYNC
10 MOUSE_Y_COUNT
11 MOUSE_X_COUNT
12 VIDEO
13 MOUSE_Y_UP/DOWN
14 MOUSE_X_UP/DOWN
15 MOUSE_BUTTON_1
16 VSYNC
17 +5V
18 MOUSE_BUTTON_2
19 MOUSE_BUTTON_3
20 GND

All the signals are TTL-level, except for the keyboard and tablet, which use RS-232 (+/-12V, inverted logic) signaling. Also, I might have X and Y on the mouse backwards, and I am not sure of the actual mouse button numbering. I don't have a keyboard or mouse in my possession, but I figure this would be useful for anyone (including me) who might try to emulate them with more modern hardware.

Cheers, Jon.
Click to expand...
I think there was an error in my analysis... Pin 12 of the IDC connector is not the video signal, that is presented on the miniature coax connector. I need to hunt a little more to figure out what pin 12 is. It looks like it is a buffered version of the CSR.4 register bit "VIDEN".
 
Last edited:
I have my VCB01 wired into a keyboard and monitor now. Some more connection information about making the connections with the bulkhead patch panel.
 

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I'm starting to experiment with the VCB01 again - this time installing one a MicroVAX I. I found a cabinet kit for cheap, but it didn't have the mini coax cable with it. In your work with the card, did you have occasion to figure out what sort of connector the coax cable uses? I've never seen one like it before. The cable looks like RG174, I just need to find a couple of those crimp on ends for it. Failing that I'll probably have to solder some pigtail leads to the board and panel.
 
I have one of the proper cables for it... the crimped-on connectors are unlike anything else I've seen... I can try to take some close-up photos, if you think that would be helpful...
 
jmdhuse said:
I have one of the proper cables for it... the crimped-on connectors are unlike anything else I've seen... I can try to take some close-up photos, if you think that would be helpful...
Click to expand...
Ah, thanks for the offer. I actually have one legit cable, in use on another system, so I know how they look. I've worked with coax in radios for a long time and I've never seen anything like these connectors. Closest I've seen to it is SMC - it's the only connector family I know of that has the "plug, that would normally be considered the male part, have a female pin, and the "jack" that would normally be female, have a male pin. But SMC includes a substantial shell around each of them and attaching threads, that aren't present on the VCB01 and its cable. Before I break out the soldering gear, I think I'll try just using the inner pin of the "plug" part of an SMC connector, and see if it will will work with the shell and nut omitted.
 
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