RS232 voltage level converter box

[Michael B. Brutman]

Tony Duell wrote:
> And the PCjr serial port is at RS232 levels anyway. The PCjr seiral cable 
> is just a cahle, no intenral componnets (I have the PCjr TechRef with 
> schematics...)

Good point - I'm looking in the TechRef and see that now too.  I don't 
know why I was assuming TTL logic levels.

> If it was used wit ha PCjr, then I would guess that the PCjr was 
> connected to the RS232 side of this coverter, and some other device, 
> using a TTL level serial port, was connected to the 20 pin header.
> 
> I can't think fo anything offhand that would have such a port. It might 
> have been something very specialised (say to control or program some 
> measuring instrument or something).
> 
> -tony
> 
> 

Still clueless.  The RS232 side of this device is male, and the serial 
adapter cable for a PCjr is also male, so it would have needed a gender 
changer to work in that arrangement.

Can I throw something stupid out here?  I'm making an assumption that it 
was for the serial port.  However, if it's just converting voltage 
levels is it possible that it was driven by the parallel port?  That's 
TTL level.  (I have no idea what they were attaching to the other side ..)


Mike