[GreenKeys] Current Loop or RS232?

[info at drukknop.nl]

A test program is also in the books on bitsaver i mentioned earlier. If 
there are more serial cards in the system, check their adressses.

there is code on our hack42.nl site to dump the contents of the core 
memory via the teletype. that way you can check if the core is still 
functional or has missing bits and you have a hardcopy of whats on the 
machine. how many kwords does the system have?

On 16-09-17 01:53, tony.podrasky wrote:
> Yes,
> 
> What you'll need:
> 
> o 9-Volt battery.
> o 1K resistor.
> o Clip leads.
> o Simpson Analyzer (multi-meter / oscilloscope)
> o Pin-out of a standard DB-9 / DB-25 - or whatever
>    kind of connector you have.
> 
> If you can find a pin-out for the connector you'll be
> way ahead, if not give this a try.
> 
> Ground the meter. Check each pin on the PDP8's I/O port
> and see if any have about 12 volts on them. If so it's
> probably RS-232.
> 
> Now, YOU'LL have to write a small program that checks for
> interrupts. If you can do that, the next thing we'll go over
> is grounding one end of the 9-v battery, and connecting the
> 1K resistor in series with the other end and touching it to
> each pin of the connector - and watch for the program to halt.
> If it doesn't halt, flip the battery around and try again (because
> RS-232 is pretty much +12v and -12v.
> 
> Let me know how that goes.
> 
> UE,
> K2EAA - TONY
> NNNN
> ZCZC
> 
> 
> On 09/15/2017 02:43 PM, Paul Heller wrote:
>> After looking a long time I finally got hold of a PDP8. I got it from
>> another ham. The guy I got it from said he used to have a teletype
>> hooked up to it.
>>
>> Is there a way I can determine if it is a current loop or an RS232
>> interface?  I assume if I guess wrong I could damage the teletype or
>> the terminal board in the computer. Is this a valid worry?
>>
>>
>> Thanks for any help. I'm a newbie to DEC computers. Maybe I can
>> finally put that tape relay in my teletype to good use.
>>
>> Paul ______________________________________________________________
>