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Re: Why no byte write on Alpha?

Our group is working on GaAs microprocessor designs, and we have made
many of the same decisions that DEC made on Alpha.
There are two main reasons to avoid byte read and write.

1) Adds a mux on reads, 
	As Mark F. from HP has said, this is no big deal in CMOS.
	but what about other technologies? We are constantly finding
	archetectural decisions that have been made based on  1.2 micron
	CMOS technology that make things very difficult for us in GaAs.
	DEC has said that the architecture is to last for XX (25?) years.
	Decisions made based on current technology often look out of place
	decades later, look at the VAX. Granted, this one instruction will not
	make or break an implementation, but DEC has done a very good job of
	designing a technology neutral architecture.

2)a read-modify-write is required on writes.
	To allow ECC protected writeback primary cache, a RMW is 
	needed to update the ECC bits.

Mike Upton
Gallium Arsenide Processor Project
University of Michigan