MC68000 "size" (was Re: modern serial terminal)

On Wed, Nov 07, 2007 at 03:42:16PM -0800, Eric J Korpela wrote: As will you and I... the MC68020 is unarguably a 32-bit processor, but the MC68000 is much more a 32-bit processor than a 16-bit processor. The external data bus _is_ 16 bits for the MC68000, but the internal register model is 32 bits. The address bus is 24 bits, not 32, but a 16-bit processor like the 80286 or the PDP-11 has 16-bit address registers, and can't access more than 64K without register segments or an MMU or something similar. The MC68000 needs no additional decoding hardware or tricky software to address its full 16M address space (which is the same size address bus as the VAX-11/750, which to all accounts _is_ a 32-bit processor). There's a reason I described the 68000 as a 16/32 processor earlier today... internally it *is* 32 bits. The bus interface is just reduced to save on the pin count, etc. Look at the size of the ALU and the accumulator(s)/data registers, then come back to me. -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 8-Nov-2007 at 00:20 Z South Pole Station PSC 468 Box 400 Temp -52.2 F (-46.8 C) Windchill -71.5 F (-57.5 C) APO AP 96598 Wind 4.2 kts Grid 332 Barometer 686.1 mb (10399 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html