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> but the WDC segmentation model was cleaner, etc... Eh, I don't think this is generally true. Intel's decision to have the segments overlap so much was defini
by mikepavone 4y ago
> but the WDC segmentation model was cleaner, etc...
Eh, I don't think this is generally true. Intel's decision to have the segments overlap so much was definitely very short-sighted, but the 8086 has a big advantage in having multiple segment registers with the ability to override which is used via an instruction prefix. This makes copying data between two pages straightforward on the 8086 whereas you need to constantly reload the databank register on the 65C816.
I think as a pure 16-bit design the 8086 is actually pretty good. It's not at all a forward-looking design though so it wasn't well suited to being the basis of the default PC architecture for decades to come.
- pcwalton 4y ago> This makes copying data between two pages straightforward on the 8086 whereas you need to constantly reload the databank register on the 65C816. Don't the MVN and MVP block transfer instructions let you specify separate data banks for the source and the destination? (I agree that the 8086 was a superior design to the 65816 in most other ways.)
- mikepavone 4y agoYou're right. If all you want to do is literally copy bytes without any other processing then those instructions will handle it.