11/45 progress & questions

[Tony Duell]

> The DL11 controller has a crystal that does odd baud rates, the only usable 
> one by any of my terminals is 110 baud (I think the crystal in it is like 
> 408.xxxx or somesuch. I read in the docs that you can use a different 

IIRC the board has a divide-by-2^n circuit between the oscillator and 
the UART, where <n> is determined by the (rotary) switches. 

Which means that one frequency of crystal will give you the standard 
doubling series of baud rates -- 150, 300, 600, 1200, 2400, etc. The odd 
frequency crystals were used for things like 110, 134.5, etc. In ganeral 
only one divisor setting gave a useful baud rate with those other 
crystals (the crystal you have presumably also gives 220, 440, etc baud, 
but nothing uses those rates).


> crystal and get more "common" (and higher) baud rates. The docs tell me what 
> speed crystal to get - but is this crystal something I can just order from 
> jameco/digikey/whoever and plug it in? The docs sound like it is only a 
> crystal swap required. Correct?

It is just the crystal that uou need to change. And I think the one for 
300/600/1200/etc baud is a normal frequency. The problem will be getting 
it in a can that will plug into DEC's socket, but I think you can just 
solder the crystal to the tags on that socket if you have to.

I beleive there are companies that will custom grind just about any 
frequency crystal. Radio amateurs used to know of such places to get the 
crystals to put PMR, etc radios onto the amateur bands. The price wasn't 
that high if you didn't mind waiting.

-tony