Date   : Tue, 08 Oct 2002 01:01:40 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: speed

"james watson" <james@...> wrote:
> Is it possible to speed a BBC micro up. Perhaps by disabling certain
> events or by any other method?.
 
All system interupts other than the keyboard and TIME can be turned off
with:
     *FX151,78,62
 
All system interupts other than the keyboard can be turned off with:
     *FX151,78,126
 
All system interupts, INCLUDING KEYBOARD, can be turned off with:
     *FX151,78,127
 
*CAUTION* - the operating system checks the system VIA on BREAK, and if it
finds all interupts disabled, as with *FX151,78,127, it does a power-on
reset, clearing all memory!
 
You could even assemble a SEI:RTS can call it to disable all hardware
interupts:
     P%=&900:[SEI:RTS:]:CALL &900
 
The operating system regulalry turns interupts back on, and enables
various system interupts. For instance, OSRDCH enables interupts, so as
soon as you try for an input, interupts will be back on again.
 
Decades ago I wrote a small program to test the execution speed of the
BBC BASIC interpreter on various platforms.  A copy is inside my Z80Tube
emulator at http://www.mdfs.net/Apps/Emulators/Tube/Z80Tube.zip the file
is Extras.ClockSp
 
-- 
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@...                - Running on BBCs & Masters with SJ MDFS FileServer
Z80+6502/CoPro+Tubes/Econet+SJ - - - - - - - http://www.mdfs.net/User/JGH/
 Never, ever, EVER, *EVER*, *E*V*E*R* use an apostrophe to make a plural