baud modifier

Tony Duell ard at p850ug1.demon.co.uk
Sun Mar 11 20:19:24 CDT 2007


> > Are there many computers (apart from the BBC Micro!) that can do 9600
> > baud but not 110 baud? I ask merely for information.
> >
> 
> I am fairly sure I persuaded a beeb to do 110 once, for dial-up to a
> cetain university to play MUD.. I think it was as simple as changing a
> jumper over, but this was about 25 years ago and so i forget exactly
> which one..  It was certainly a non-permenant mod..

I wasn't aware of any such jumper... The baud rate generator in the Beeb 
is inside the Serial ULA (the acutal serial chip is a 6850), and I didn't 
think there was any way to get that to generate the appropratie output 
frequency. 

I certainly remeber the fun a friend of mine had linking an ASR33 to his 
Beeb, and he was enough of a hacker to know just about every jumper on 
the board. Output was not a problem, you could bit-bang that using the 
'break' signal, but there was no way to read the state of the RxD line 
for input. We may well have ended up bit-baning it both ways using pins 
on the user port.

> 
> On 11/03/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> >
> > [1] Maplin, the company, are still going, but their range of components
> > is a joke. They now mostly sell electornic toys, Lo-Fi, etc.
> 
> Tell me about it... I cleaned out two stores this weekend to get
> enough 33uF 25V electrolytics for a repair I was doing... hardly
> exotic, I thought, but the total quantity between two stores?  Five!

I've beem told that 1k resistors (that's the standard, 0.6W 1% resistors, 
nothing exotic) are 'order only' components at some shops. 

-tony



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