realtime 'pd' problems

[NJCross]

Hi,
I'm using pd (Pure Data) and YDL 2.2 on a PowerBook 500MHz 'pismo'
and I'm unable to access my built-in microphone using pd's adc~ object.

When I start-up pd I get these error messages:

[root@localhost root]# pd
couldn't open MIDI input device 1
couldn't open MIDI output device 1
opened 0 MIDI input device(s) and 0 MIDI output device(s).
OSS: requested audio buffer size 7056 limited to 4096
error: OSS: SNDCTL_DSP_CHANNELS failed /dev/dsp

Midi isn't an issue here.I don't use it. But,not being able to set the audio 
buffer size and 'error: OSS: SNDCTL_DSP_CHANNELS failed /dev/dsp' are 
puzzling.
btw - dsp works OK on sound files in 'pd', no problem.

Can any YDL/pd users suggest a possible solution?
Thanks in advance,
Keith