Re: A89: Starting out assembly, need help
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Re: A89: Starting out assembly, need help
-----Ursprüngliche Nachricht-----
Von: Daniel7073@aol.com <Daniel7073@aol.com>
An: assembly-89@lists.ticalc.org <assembly-89@lists.ticalc.org>
Datum: Freitag, 4. Dezember 1998 01:25
Betreff: Re: A89: Starting out assembly, need help
>
>In a message dated 12/3/98 8:37:25 AM Pacific Standard Time,
>nlmueller@students.wisc.edu writes:
>
><< No, the m68k is executing five instructions at once. This way, on a 10
MHz
> chip it takes 5 cycles to finish one instruction, but only 1 cycle to
> finish the next instruction. >>
This is plain wrong. I guess you are referring to the 68000 ??
The 68000 is not pipelined. Its using a microcode sequencer (and even a
nanocode sequencer - its
the only CPU [afaik] who has such a thing)
It takes at least 4 cycles for every instruction to execute. No instruction
overlap.
However on the 68020 and 68030 certian instructions do overlap (actually bus
cycle/execution cycles do). The 68040 is fully pipelined and executing about
6 instructions at once, with max. one retiring each cycle. The 68060 is both
pipelined and superscalar. Its executing up to 20 instructions at once with
max. two cycles plus one branch per cycle.
But this is not interesting for us, since the TI89 just has a 68000.
This kind of information can be found in the CPU usermanuals. Check out
motorolas website.