Steve,

From: DALLAS SEMICONDUCTOR ERRATA SHEET DS89C420 Revision A2 06/15/01

"1. The maximum operating speed of the microcontroller core over the temperature range and voltage
limits is 33 MHz. If the clock multiplier is used, the external oscillator or crystal frequency must be
scaled appropriately so that the internal clock speed does not exceed 33 MHz.
Work Around: None. Operating speed will be increased in later revisions."

The A-2 rev. is what i'm being shipped.

regards,
p