Hi,

Darrel correct me if I am wrong, I am a bit rusty here.

The shadow registers are not memory mapped but are actually hardware registers, a single level deep hardware stack that can save your context (W,Status, BSR). Optional during <b>call, something s , </b> or a <b>return, something s , </b> and automatic when entering interrupt. You decide whether you want to restore them by Retfie Fast . So when a low priority interrupt (0x0018h) is interrupted by a high priority one, the context saved while entering the low priority is lost. Thus it works best if you are using only HP Ints or using it for only HP Ints.