The P89V51RD2 comes with SoftICE, which is a variation on Keil's FlashMon. Although it is a monitor, it plugs into Keil's uVision and behaves just as ICEs do - single-stepping, breakpoints, comfortable access to internals.

Has its limitations (of which the occupied UART is the biggest pain), but this modification eats much less of other resources (notably ERAM (the "internal external" RAM)) than the original FlashMon, storing intermediate data into the boot section of FLASH. For manual, you must go to the SST site (you certainly have noticed my rants about the P89V51RD2 being a relabelled SST product rather than a genuine NXP part?)

JW