baud modifier

Tony Duell ard at
Sun Mar 11 14:28:10 CDT 2007

> I'm thinking of a device that would step down the speed of an rs232
> connection from, say, 9600 to 110.  The idea is to allow a computer that
> can't do 110 to talk to an ASR33 teletype.  Does such a device exist?

Are there many computers (apart from the BBC Micro!) that can do 9600 
baud but not 110 baud? I ask merely for information.

> What's it really called?  Does anyone have any schematics for one?

I believe it's a subset of the functionality of an RS232 'protocol 
convereter'. Of course 'protocol conmverter' covers a lot more than 
things with an RS232 itnerface on each side, but I've references to units 
that will change baud rates, parity, etc.

I have a thing called a 'Ferret'. It comes in an attache' case sort of 
housing, and it has the lights-n-switches of an RS232 breakout box, a 
couple of ZIF sockets, cassette interface jacks, D-connectors for RS232, 
current loop, and parallel, a keypad., LCD display, and strip printer. 

Amongst the features of this unit is that it will interface between Rs232 
and current loop _with different baud rates on the 2 interfaces_. Sounds 
like just what you need, but no idea where you'd find one. BTW, it'll 
also do serial (Rs232 or current loop) to parallel interfaceing, work as 
an EPROM programmer, print out data from either serial interface, act as 
a line monitor on an RS232 interfacem etc. You can even program it 
yourself in Z80 machine code.

'Electronics, The Maplin Magazine' (A UK electronics mag, now long 
defunct, published by Maplin who were a major hobbyist component supplier 
back then [1]) did a series of projects to make a RTTY station. One of 
them was a baud/protocol convereter (to converter bwrween 5-bit 45.5 baud 
RTTY and, say, an 8 bit 1200 baud computer serial port). IIRC, it was a 
couple of dumb40 pin UART, some kind of clock gneerator, and a little 
(very little) glue logic. Agai, I have no idea where you'd find the 
article now, but it did include a schematic.

[1] Maplin, the company, are still going, but their range of components 
is a joke. They now mostly sell electornic toys, Lo-Fi, etc.


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