I was aware that nobody actually intended the O/P use a member of that family. Today, however, one can use an ARM that's capable of real-time emulation of an 805x with large memory, not that anyone would do that.

The segmented architecture of the 8088 became popular in PC's only because the IBM folks weren't smart enough to make a product work. They tried the MC6809 among others, but, thanks to political infighting, etc, they ended up with a circuit that looked suspiciously like the Intel prototype of an i80188 application, and adopted it at the last minute in order to avoid being shut down. They never did manage to get a 68008 to meet their needs and ultimately accepted the 8088, with its segmented memory architecture despite the fact they'd rejected the MC6809 because it used an essentially similar construct, simply because they'd been presented with a working circuit at that late date.

I've used an 805x MCU with a 320 KB memory, though the 805x has served only as an address generator. Clearly, it's possible, but really not a good idea. There are, I believe, some 805x's that support larger-than-64KB data and/or code space though I'm not familiar with their features, some of which clearly support the larger memory model. Since the O/P posted on the 8052.COM site rather than some other, I'd guess he wants to use the very good instruction set that MCU provides.

Now, you said, "then they definitely have a reason to dislike the use of a 8051 for accessing 16-bit RAM." which confuses me somewhat. 16-bit RAM is not byte-wide, and 805x's are, after all, byte-processors.

The choice of MCU's, as you've said, should be made on the basis of system requirements and not just one's preference for one MCU over another. There's been no explanation from the O/P of why he needed a large memory map, nor even whether it was for code or data. He did say it should be on-chip, though, and I don't know of any 805x with a really substantial amount of data space on board. I'd be happy to see it, though, provided it would also be accessible by external hardware.

RE