I'm adding an off chip external SRAM to a MSC1210Y5 (32K Flash ROM, 256 internal RAM, 1024 On-chip external RAM). For discussion purposes, let's focus on the external RAM. I'm mapping the on-chip ext RAM to 0x0000 - 0x03FF (with no flash ROM mapped as data memory - all flash ROM is program memory). Now when I access ext RAM address 0x0400, it accesses my off chip external RAM which is how it suppose to work.

My question, when I'm accessing ext RAM address, 0x0000 - 0x03FF, I still see the *WR & *RD lines active. Is this how this chip works? I was expecting that if you access only the on-chip external RAM, the chip inhibits any off-chip access. Thanks.

-John G-