These guys have thought about the problem some for RS-232 (not Mac, uses multiple handshake lines) and software controlled handshakes: http://pdfserv.maxim-ic.com/en/an/AN827.pdf
So the level conversion is done, but other Mac issues remain.
I've also done some digital oscilloscope/FFT work with the built in sound input A/Ds in PB500s, PB1400s and beige G3s along with some REALbasic programming with Sound Manager calls. I found that under some circumstances there is a startup transient when you call for a series of samples to be made, and many need to be discarded before waveform capture. In the PB5XXs the codec is a Crystal Semiconductor CS4216, and if you examine the input circuit recommendations you can see where to bypass the input AC blocking capacitors and build a DC coupled outside preconditioner that level converts to the input level of the A/D that is offset by the REFBUF voltage level, or for non-precision DC work to an approximation thereof.
My current project is to interface a National Instruments SCSI-GPIB-A box using REALbasic and some downloaded code to interface to the GPIB. I want to drive a varied collection of things beyond A/D and D/A including logic analyzers, universal counters, relay boxes and programmable lab bench supplies.
So the level conversion is done, but other Mac issues remain.
I've also done some digital oscilloscope/FFT work with the built in sound input A/Ds in PB500s, PB1400s and beige G3s along with some REALbasic programming with Sound Manager calls. I found that under some circumstances there is a startup transient when you call for a series of samples to be made, and many need to be discarded before waveform capture. In the PB5XXs the codec is a Crystal Semiconductor CS4216, and if you examine the input circuit recommendations you can see where to bypass the input AC blocking capacitors and build a DC coupled outside preconditioner that level converts to the input level of the A/D that is offset by the REFBUF voltage level, or for non-precision DC work to an approximation thereof.
My current project is to interface a National Instruments SCSI-GPIB-A box using REALbasic and some downloaded code to interface to the GPIB. I want to drive a varied collection of things beyond A/D and D/A including logic analyzers, universal counters, relay boxes and programmable lab bench supplies.