Date   : Sun, 29 Jul 2007 17:13:22 +0100
From   : dominic@... (Dominic Beesley)
Subject: Comms software

Hi all,

I'm fairly sure the serial buffering works ok, my BASIC serial link test 
program at (oh pants my website has been eaten by demon well the basic 
program that was there) didn't lose any incoming data, the MOS asserted the 
hardware control in plenty of time and not a byte was lost.

I did do some "improved" (hacked) buffering code to try and get better 
performance when I was doing my Contiki port. It sort of worked for a while 
then went crazy for a bit.

I think Tequila must do its own buffering as the standard MOS code seemed to 
be a bit buggy IIRC

I agree however that 19200 cannot be sustained although in Tequila it
is a fair bit quicker doing XModem at 19.2 than at 9.6 again ultra reliable
at 19.2 on a longish (50') cable with no shielding or special buffering for
RS232->RS432.

I'd dearly love to find a full version of Tequila or Dave Sainty or another 
better terminal program (the free version has a ***king annoying delay at
startup and misses out on Y/Z Modem).

Cheers

Dom


----- Original Message ----- 
From: "Sprow" <info@...>
To: <bbc-micro@...>
Sent: Sunday, July 29, 2007 4:40 PM
Subject: Re: [BBC-Micro] Comms software


> In article <46AC6AF2.2060009@...>,
>   Andrew Benham <adsb@...> wrote:
>> Sprow wrote:
>
>> > Isn't that why you can set the handshake threshold with OSByte 203?
>> > Presumably a reliable link can be achieved by increasing this value 
>> > from
>> > its default of 9 to (say) 18 or higher?
>>
>> Sorry, that's too late.  The bottleneck is in the interrupt service
>> routine, reading the characters from the UART and putting them in
>> the buffer.
>
> Another plan foiled.
>
>> I'm now thinking whether there's a way to put a 16550 on the 1 MHz bus
>> and use NMI to handle it.  Could speed up my program to backup my hard
>> disk to the serial port...
>
> Could you just lift the IRQ pin out of its socket and wire it across to
> somewhere near S9? The MOS wouldn't see UART IRQs any more and you'd be 
> free
> to write an NMI handler to get bytes yourself, or one of my second serial
> port boards
>  http://www.sprow.co.uk/bbc/extraserial.htm
> with a track cut from IRQ and wired to NMI,
> Sprow.
>
>
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