question about CPU operations

[dockery@griffin.cuc.ab.CA (Sean Dockery)]

I have a small question about the old 6502 CPU in the old Apple II's.

In the Apple II Reference Manual, it states that the 1.023MHz 6502
requires approximately 300ns for a read operation and 100ns for a
write operation.

However, it is also documentation that performing a write operation is
carried out by first performing a read of the datum in a memory
location followed by a write of the datum in a given register.

My question is simply,

	Does the write operation of the 6502 CPU require 400ns or the
	100ns as stated?  I have a feeling that a write *operation*
	actually requires but 100ns, but a write *instruction*
	requires 400ns to execute.

Can anyone clarify which is the case?  How long does it actually take?

sean
--
# internet: dockery@griffin.cuc.ab.ca   | "alone.  death can't hold a candle
#      -or- dockery@pro-calgary.cts.com |  to it, and hell is a poor synonym"
# pro-line: dockery@pro-calgary         |                       -stephen king
#     uucp: crash!pro-calgary!dockery   | disclaimer: i am unemployed