[rescue] VT420 ConnectivityQuestions

[Steve Hatle]

I'm 99.9% sure you need to go through MMJ. I used to put out a lot of 
these for POS retail, and I can never remember using the DB-25 for 
anything.

I think the terminals came in the box with a short MMJ cable and an MMJ 
to DB-25 adapter, or we bought them at the same time we bought the 
terminals. They were DEC branded, and I may have a couple in my stash 
since I saved a 420 from there. This was all 20+ years ago, but if you 
really need an adapter and/or cable let me know and I'll dig.

Steve

> Lionel Peterson <mailto:lionel4287 at gmail.com>
> May 2, 2022 at 7:39 PM
> I researched this a while ago, but now I can't find it: can I connect 
> to a VT420 terminal through the DB25 connector on the back, or do I 
> have to use either of the MMJ ports?
>
> My initial tests tell me the DB25 is simply for a local printer, the 
> terminal sessions want to be on one of the MMJ ports, correct?
>
> Can someone help me configure a 'no soldering' solution to connect my 
> VT420 to the on-board UART on the RPi 4 GPIO pins? I assume 
> www.pacificcable.com is the preferred vendor, and what I need is a 
> cable to go from MMJ on the terminal to a DB9 Female connector, 
> probably null modem, since I want to hook the terminal to the TX/RX 
> pins on the RPi 4 thru a level converter that takes TTL-level signals 
> to 'proper' RS-232 level.
>
> My research shows the MMJ to DB9 or DB/5 requires shorting a few pins 
> together, and that's hard to do with an MMJ->DB9 adapter shell - 
> pacific cable shows what appear to be pre-built adapters for $6 vs 
> $3.50 for DIY adapter shells
>
> Any advice? Reccomendation?
>
> I think I need an MMJ cable & pre-built adapter shell.
>
> Ken
>
> Ken
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