Frequency-dependent parameters question

[ndru]

According to the AC Characteristics table for the W65C816S, certain parameters are dependent on the frequency at which the chip is being run at, eg. tAH = 10ns at 14MHz, and 40ns at 2MHz. I understand that some parameters are obviously frequency dependent, such as Clock Pulse Width Low and High, but why do the Hold and Setup times of the chip change?

[GARTHWILSON]

You're looking at the 1.8V spec.s. The part can work at 1.8V, but it was primarily intended for 5V; so when you cut the power supply voltage down to 1.8V, the internal propagation delays and transition times are slower.

[kc5tja]

Also, it looks like the original chips were 'binned' for speed -- some are rated for 2MHz tops, some for 4MHz, etc. As yields improved, quality became more consistent, and now they essentially only have one processor -- the 14MHz part. Which I guess is supposedly able to go as fast as 20MHz, but whether it's consistent is unknown to me.

[ndru]

Thanks for the explanations, I never considered the VDD row.