This question is under investigation. On the Integrated Development System, the BIOS is in the flash when delivered. There is a DOS and a Linux partition on the hard disk. A VxWorks demonstration program resides in the DOS partition. The Phoenix BIOS will fit into 256K of the flash.
Burst mode is supported.
It is possible to use any frequency up to 66 MHz. See the Clock discussion in the ZFx86 databook. Read the BUR documentation in the databook for more details. The ISA memory mapper is simple. It is fully described in the ZF logic chapter of the data book, and highlighted in the ZF Logic Chapter of the Training Manual.