Hi Peter,
as you know, on the DS8c310 the code fetch speed is not increased for one instruction, but the fetched instruction is beeing processed faster (you need for most of the instructions 4 clock cycles instead of the 12 of a standard 8031).
Nevertheless, the speed of the Eprom is not a problem running at 11.059 Mhz: an "old" Eprom with 200ns would fit without problems (see AN57 on www.dalsemi.com).
But for other reasons I MUST maintain the 11.059 Mhz.

The original question was if there is another alternative to the DS80c310. The best answer would be: "Yes, there is an alternative from xxx (not Dallas), which is pin- and function compatible with the DS80c310. So go ahead with your plans on using Dallas, since there is a second source".
Another answer could be "Look, there is another uC from yyy, which needs only 3 clock cycles instead of 4".

Best regards,

Gerardo