Personal computer having normal and high speed execution modes

Claim 1

A personal computer having a high speed microprocessor responsive to a mode select signal for executing applications programs, in either a FAST mode or a SLOW mode, where the high speed microprocessor is software compatible with a slow speed microprocessor, the high speed microprocessor having an internal pre-fetch queue, the high than the pre-fetch queue on a slow speed microprocessor, said computer further comprising: (a) a RAM memory having addressable memory word locations comprising a plurality of bytes; (b) a clock generator responsive to the mode select signal for generating the clocking signals to said high speed microprocessor such that (i) in the slow mode, the clocking frequency is approximately the same as the normal clocking frequency for a slow micro-processor, and (ii) in the FAST mode, the clocking frequency is higher than the normal clocking frequency for a slow microprocessor; (c) logic means responsive to the mode select signal and said clock generator for controlling the wait state of said high speed microprocessor when in the SLOW speed mode so that every other word access to the RAM memory by the high speed microprocessor requires two consecutive word fetches to the same memory address to obtain the contents of the location addressed thereby enabling the high speed microprocessor to execute application programs prepared for a slow speed microprocessor in the SLOW mode, on an average, at substantially the same speed as the program normally runs an applications software package on a slow speed microprocessor; and (d) switching means to switch the clocking frequency to SLOW mode during any Direct Memory Access (DMA) cycle.