PDP 11/03

Johnny Billquist bqt at update.uu.se
Mon Nov 9 16:19:28 CST 2015

On 2015-11-09 23:05, Noel Chiappa wrote:
>      > From: Henk Gooijen
>      > As far as my limited PDP-11 knowledge goes, none of them used
>      > handshake.
> I'm pretty sure this is true of all the ones that had a hardwired serial
> console - it's definitely true of the 11/23 and J11 chip ones (/73, etc), and
> probably the 11/03's too (although it's been 30+ years since I used one of
> those, so don't hold me to that :-).
>      > So, Rxd, TxD and GND is all you need to connect.
> Errq, many of them _require_ a loop-back between a pair of pins on the
> Berg/DuPont connector to operate - this is true of the DL11 (M7800 - UNIBUS),
> DLV11 (M7940 - QBUS), DLV11-J (M8043) and 11/23+, for instance), and probably
> the 11/83-84 too. So just connecting up R, X, and Gnd alone won't do it.

Good point. The DL(V)11 is a general serial interface. If it's like the 
KL-8 cousin, it can use both TTL, EIA and 20mA. Converters for EIA and 
20mA is on the board, and you route the TTL signals through one or the 
other converter, and then use the other end of those converters for 
connecting to the external device. So, different cables/BERG connectors, 
gave you different interfaces. Of course, you can reroute the cabling in 
the BERG connector yourself as well...

>      > Also, common (?) is *no* parity.
> That, and number of bits, I have no idea about - we always changed things to
> our local standard (8 bits, no parity, 2 stop bits, IIRC) straight away. Best
> to check the hardware, and see what it's set to, and either set it to what
> you're using, or change what you're plugging into it to match.

Agree. But in general I would concur with Henk on this. Most everything 
in DEC used to be 8N1, except for really old stuff, when they were fond 
of mark parity.


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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