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Discussion on: Why is 32-bit called x86 and not x32?

jeroen1205 profile image
Jeroen Jacobs • Edited on

No, the 286 had a Protected Mode, but it was not 32-bit. It was actually a 24-bit addressing mode which allowed access to 16MB of RAM.

Since the 286 was strictly a 16bit processor, it used segmentation even in Protected Mode. The segment register was loaded with a 16-bit index, which pointed to an entry in a descriptor table. This entry contained the actual 24bit base address.

If this sound complicated to you, you are right, it is. 286 Protected Mode was barely used. You were still restricted to 64Kb addressing within that one segment.

tobiassn profile image
Tobias SN

Huh. I read that Protected Mode was introduced with the 286, and just assumed that it meant that the 286 was 32-bit. Thanks for the clarification.