>8088 is actually a 20 bit CPU
It’s more complex than that. To specify an
address you use a 16 bit base register and a 16 bit offset to form a 20 bit physical address (recalling the hack). Notice the use of two 16bit instructions. To access more than 64KB of memory, this hack must be use i.e. some commentaries associated this to "brain damage".
To compound the memory restrictions; the original IBM PC can be expanded to 256K (i.e. maximum memory using IBM parts at that time(1)).
Usually, "Bit’ness" refers to GPRs and Pointers.(simplifying). Note that the current X86-32 can ready handle 64bit data sets(e.g. 3DNow, SSE, AMD32's EV6 FSB, internal data path).
Reference
1.
http://en.wikipedia.org/wiki/IBM_PC