12 Mar
2007
12 Mar
'07
1:43 a.m.
On 12/03/2007 07:42, Rob wrote:
On 12/03/07, Tony Duell <ard at
p850ug1.demon.co.uk> wrote:
Having had a quick squint (well it is 7am) at the beeb schematics, I'm
pretty sure it was changing S28/S29 - these alter the inputs to IC42,
a 74LS164 4 bit counter, used as a divider on the clock input to the
Serial ULA
That's right, and it's a standard mod, described in Acorn's notes.
Changing S28 increases the baud rate so you get 108 baud instead of 75.
It affects the cassette baud rate as well, of course.
--
Pete Peter Turnbull
Network Manager
University of York
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.