a bad day for vaxen

[Dan Gahlinger]

yeah I dont have a dremel, and I'm not good that way.
it'd be best if I could just test some known good cables

even with a monitor hooked up, and let it wait over 5 minutes I got nothing.
even 15 minutes and still nothing.

one system I get a "blue" screen and thats it
on another i get the color test patterns, then nothing
the third i get a black screen and monitor says its receiving no signal.

:(

Dan.
----------------------------------------
> From: dave06a at dunfield.com
> To: cctalk at classiccmp.org
> Date: Sat, 23 Feb 2008 07:08:19 -0500
> Subject: RE: a bad day for vaxen
> 
>>do I need a null-modem cable or straight?
>>yes I know it's non-standard, but still.
>>I have a DEC 9 pin adapter.
> 
> An essential tool for anyone interfacing to serial equipment is a
> "light box" - just a box with LEDs to show which signals are being
> driven by a particular interface. I prefer the kind with two-color
> LEDs which show the polarity of the signal.
> 
> To determine if you need a null modem, you need to determine which
> signals are being driven - You can use a LED or a multimeter set
> to measure current (few milliamps), in series with a suitable resistor
> to limit the current (few 100 ohms).
> 
> The PC is setup to look like a DTE (Data Terminal Equipment), which
> means it drives (25 pin connector numbering):
> 
> TD - Pin 2
> RTS - Pin 4
> DTR - Pin 20
> 
> The device which interfaces to it must look like a DCE (Data
> Communications Equipment) and should drive:
> 
> RD - Pin 3
> CTS - Pin 5
> DSR - Pin 6
> DCD - Pin 8 (Not usually required unless the software is
>   expecting a modem)
> 
> 
> Note that the PC 9-pin connector has a different pinout that the
> traditional DB-25. This little chart may help:
> 
> [View this message with a fixed pitch font - if you can't easily
> do that, save it to a file and view it from a text editor running
> on a text mode (non-graphical) screen]
> 
>                   PC (25 pin)                            AT (9 pin)
> 1   2   3   4   5   6   7   8   9  10  11  12  13    1   2   3   4   5
>  14  15  16  17  18  19  20  21  22  23  24  25        6   7   8   9
> 
>     Signal name               Origin   25-Pin(PC)  9-Pin(AT)
>     --------------------------------------------------------
>     Protective Ground   (GND)   ---         1          -
>     Transmit Data       (TXD)   DTE         2          3
>     Receive Data        (RXD)   DCE         3          2
>     Request To Send     (RTS)   DTE         4          7
>     Clear To Send       (CTS)   DCE         5          8
>     Data Set Ready      (DSR)   DCE         6          6
>     Signal Ground       (GND)   ---         7          5
>     Data Carrier Detect (DCD)   DCE         8          1
>     Data Terminal Ready (DTR)   DTE        20          4
>     Ring Indicator      (RI )   DCE        22          9
> 
> Connectors viewed from rear of PC.
> 
> With all your cabling attached to the VAX, check the current being
> provided on TD, RD, RTS, CTS, DTR and DSR - note that not all of
> these may be driven - it is common practice to "loop back" signals
> which are not available on the interface. For example, RTS may be
> connected to CTS - so that when the PC asserts RTS, it will see
> CTS - even though that signal is not provided by the terminating
> equipment.
> 
> If your VAX cable is providing current on RD, and NOT on TD, RTS
> or DTR, then it should be directly connected to a PC.
> 
> If the VAX cable is providing current on TD and NOT on RD, CTS or
> DSR then you will need a "null-modem" cable which swaps TD/RD,
> RTS/CTS and DTR/DSR.
> 
> If your interface is providing current on a combination of signals
> which originate at both sources (example, TD and CTS) then you have
> a mis-wired cable.
> 
> 
>>I think my RJ12 (6 pin phone like cable with locks off-set) are no good.
>>
>>i have no idea where to get "new" dec connect cables :(
> 
> I've had good luck making MMJ connectors from RJ-45 Ethernet connectors
> with a dremel tool - if you are careful, the result fits nicely, and
> even locks into place correctly with the tab. I can post a couple of
> photos if you want to see.
> 
> The adapter I created to interface the PC to my VAXen looks like this:
> 
> [View this message with a fixed pitch font - if you can't easily
> do that, save it to a file and view it from a text editor running
> on a text mode (non-graphical) screen]
>            
>   6 3 7 - 2 20   DB-25 serial pins (so chart above for names & DB-9)
> 
> + | | | | | | +
> + | | | | | | +  View of top side of connector
> +             +  Looking down on connection pins.
> +             +
> +-------------+
>    | Cable |
> 
> Since RTS/CTS are not provided on the VAX MMJ interface, my cable
> also loops RTS to CTS.
> 
> This connects directly to the PC (no null modem).
> 
> 
>>i got 2 systems going out of all of them. not very good... 
> 
> Just in case it's "been a while" ... Don't forget that some VAXen
> seem to take quite a few seconds before the serial output of the
> self-tests starts after power-on. The first time I powered up a
> VAX I thought it wasn't working at first...
> 
> 
> Dave
> 
> --
> dave06a (at)    Dave Dunfield
> dunfield (dot)  Firmware development services & tools: www.dunfield.com
> com             Collector of vintage computing equipment:
>                 http://www.classiccmp.org/dunfield/index.html

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