I do not know the similarity between the Dallas chip and the Philips Mx series ('51 with 16Mb addressing) - for all I know they may be equivalent - but the tools for the Mx are at
http://www.semiconductors.philips.com/products/...ools/8051/

Anyhow, you may want to check www.phytec.com, they are pretty quick to pick up new derivatives.

Erik