To:         Jefferson@marketing@GRiD
            Tindle@Development@GRiD
From:       Strang
Subject:    1537 422 and keyboard ports
Date sent:  10/18/89 3:29 PM
Copies:     Schlipper@marketing@GRiD
            Bailey


Judy and Jeff,

Here is a list of what I would do with up to 6 additional signal inputs for the 1537s 422 serial port.  Jeff tells me that only 1 or 2 additional signal inputs are really possible, but I did 6 choices just in case.  They are arranged in order of preference, with choice 1 being most preferred and choice 6 being least preferred.  The signal names I give are what I think the added signals would be called, based on the existing signal names.  The chip numbers are from the 02-March-89 schematics, so they may be out of date.

   Signal Name    chip and pin      where on 25 pin
---------------------------------------------------

1. SETXCA~        26LS32 U56, pin 10    11
Allows balanced TRxCA input

2. SRI_SI~        26LS32 U56, pin 14    12
Allows balanced DCDB, RTxCB, or SYNCA input

3. SDSRA~         26LS32 U55, pin 10    13
Allows balanced CTSB or TRxCB input

4. SSYNCA         26LS32 U56, pin 7     21
5. SSYNCA~        26LS32 U56, pin 6     23
Allows full time balanced SYNCA input, independent of any strang bit settings.  These two should be done together, and at the same time SYNCA~ on the 85C30 should be routed to U56, pin 5, instead of U52 (74HC157), pin 9, and pins 10 and 11 on U52 should be grounded.

6. SDCDA~         26LS32 U56, pin 2     19
Allows balanced DCDA input


I notice that you have changed the 1537 keyboard input to a 9 pin connector.  I looked for tempest PC/AT compatible keyboard sources at AFCEA this year, and found that there were 3: IBM, Wang, and a third party whose name I don't recall (ITC?).  Wang uses a DB9 connector on their keyboard, and it sounded like one of the other 2 did also, though it was not known if they used the same pinout.  I think Wang used a male connector on the keyboard and a female on the computer, as is currently planned for the 1537.

My point is, if there is a tempest PC/AT compatible keyboard maker who uses a DB9 connector and we are also using one, it would make a lot of sense if we arranged our connector's sex and pinout to match the keyboard.  I can't find my notes from that AFCEA show right now, but I did get names for appropriate people at Wang.  I gave them Judy's name and number also, so they may have contacted her since.  Are you guys interested in pursuing this?  Should I do anything?

Will