Thanks Steve,
I will check that out.
I spent some time this weekend monitoring the bit streams between my pc and the device with a scope to both confirm the bit width is ~ 17uS, which it should be for 56.7k, and also to get a look at the bit patterns of returned info.
Then I did a simple....
Main:
bo = 1
high 5
bo = 1
low 5
goto main
To see what bit width I would see from a 4Mhz clock.
And this came out to around 50uS.
Perhaps if I removed the 'bo = 1's It would speed up a little, but no where near the speed needed. In order to read 56.7
Looking in PBC.INC, it looks to me like 9600 baud is right at the timing limit with a 4Mhz clock. And since 56.7 is such a large jump, I think now a 40Meg chip slowed down to around 24Mhz might be the easiest way to do it using the built in SERIN / SEROUT commands.
Anyway, I also checked out maxim's MAX3110E SPI/rs232 chip, and requested a couple of samples. I built up a schematic for it, and when they come in, I should be right on it.
If I get this working I'll post the schematic and code.
However, the reallity of my project is that I am only sending 2 bytes to the device, and these always the same. And the device is sending 4 bites back.
I think with a little work, I can replicate the command bit stream with a 20Meg crystal. Decoding the incoming bytes will be the hard part.
After sweating over that approach, I'll be eager to play with the Max chip.

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