Yes, the extra cycle has to do with slow memory access (1980's!) and is
there on every MSX, even long before the MSX engine chip was there. And it
has to stay because of the many programs that rely on timing based on
instruction time.
I did not know this in 1987 or so when i wrote a software driven rs232
driver via the joystick interface. Counting instructions and the time they
take from the book just did not want to match with what i saw on my scope
until i decied to add one state based on my experiments. Great fun!
Later i discovered it in a book as a confirmation (is this not in the
Redbook?).
Hans
-----Original Message-----
From: Frits Hilderink [mailto:[EMAIL PROTECTED]]
Sent: 05 April 2000 16:15
To: [EMAIL PROTECTED]
Subject: Z80 T-States
Is it true that every Z80 instruction on a MSX takes
one extra T-State because of a delay caused by
the MSX Engine ?
In other words, a NOP instructions takes 4 T-States,
but in a real MSX it would take 5 T-States.
Frits
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