R65C02P4 (6502) microprocessor R/W pin state while suspended
The main purpose of RDY is to 'stretch' the bus access time for slow memories. During a write cycle that slow memory needs to see the data and active Write signal telling it to write the data. 

The description in the datasheet is incomplete. The entire bus, including data and control lines (not just the address lines) is halted. When RDY is detected during &phi;2 the data bus and /W line are already active. This state will be held through subsequent &phi;2's until RDY is released.