Author: Eugene Nalimov
Date: 23:39:39 03/09/00
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On March 10, 2000 at 02:00:32, Christophe Theron wrote: >On March 09, 2000 at 19:23:01, John Coffey wrote: > >> >>>So by your definition, a PC with SDRAM is 64-bit, whereas a new Pentium III with >>>Rambus memory is 16-bit. Or maybe 256-bit, due to the interface to the L2 cache? >>>Gets confusing quickly... >>> >> >> >>I am not going to make any claims to modern processors that I don't program. >>The 68000 fetched data and instructions from memory 16 bits at a time. I don't >>see anything wrong with my definition. >> >>John > > >I have heard that some 64Kb limitations (for code or data) apply to the 68000. I >don't understand why, as it has 32 bits registers. The 16 bits address bus is >very similar to the 386sx 16 address bus (the 386sx had 32 bits registers). > >What's the problem with the 68000? Are there really such limitations? > > > Christophe First 32k of address space (and of course last 32k) can directly addressed used 2 bytes address included in the instruction, not 4 bytes address, so typical instruction occupies 4 bytes instead of 6. So if you'll manage to allocate all your globals there, your program would be noticeable shorter. Important consideration for the systems with limited ROM/RAM. Eugene
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