Connecting LK250 to VAXmate

Rob Jarratt robert.jarratt at
Fri Nov 15 11:05:25 CST 2019

Someone else has given me the information now, so no need to do anything.






From: Rob Jarratt <robert.jarratt at> 
Sent: 14 November 2019 20:59
To: 'Jason T' <silent700 at>; 'General Discussion: On-Topic and Off-Topic Posts' <cctalk at>; rob at
Subject: RE: Connecting LK250 to VAXmate


Hello Jason,


I have all the bits necessary to make a cable for the LK250 now, without butchering the IBM Model M cable I bought (which turns out to only have 4 out of 6 wires). All I need now is the pinout. I have the VAXmate technical description which gives me pin numbers and signals for the cable, but I am not really sure how that maps to the connector pins. So, if you, or anyone else, could tell me the pinout for the LK250 cable I would be very grateful. From the technical description it looks like I may be able to get away with only 4 wires, not sure.






From: Jason T <silent700 at <mailto:silent700 at> > 
Sent: 15 June 2019 14:46
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at <mailto:cctalk at> >; robert.jarratt at <mailto:robert.jarratt at> ; rob at <mailto:rob at> 
Subject: Re: Connecting LK250 to VAXmate


On Sat, Jun 15, 2019, 03:28 Rob Jarratt via cctalk <cctalk at <mailto:cctalk at> > wrote:

I recently acquired a VAXmate with an LK250 keyboard. The problem is the
keyboard came without the cable. It uses an 8-pin SDL connector and the
usual tiny MMJ-like connector at the keyboard end. I don't know the pinout
and I don't have the necessary crimping tools, is there any source for such
a cable?


Is it actually MMJ, with the offset pin, like a DEC serial cable? Or is it just an RJ connector like a telephone handset?  And is the SDL end the same type as on an IBM model M keyboard?


I have a VAXmate buried in storage. With enough prodding I could dig it out and try to determine the pinout of the cable. 

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