Hi Jay & Peter,

Peter.. I did consider just mapping the upper 32k program space into the upper 32k data space, but as you said, that would only leave me with the lower 32k data space for RAM and I/O.. my application requires at least 32k of data RAM and handles quite a lot I/O space.. so I use the '154 to swap the upper 32k of program space into the I/O space when it needs writing, and then back into the program space when it's code needs to be executed and access to the I/O is required. Ideally I'd like to access even more RAM, but I'm deciding whether I can really be bothered with paging (the reason why I can't stand PICs, and why I hate VESA graphics programming in real mode on a PC!!!). By the way, do you know where I could get the schematic of the standard development board?

Jay.. Yes I agree, the '154 is a bloody ugly beast.. quite annoying seeing as I'm only going to be using 4 of it's outputs. I didn't know there was a '154 circuit going about.. you mean to tell me I didn't need to sit in bed for two hours giving my self a headache deciding what to do?!?!?! Infact, whilst I'm writing this, it's just occured to me that it might be possible to use a '138.. hmmm..

Bye for now.