The Importance of Terminology's Quality

[Martin Gregorie]

On Fri, 22 Aug 2008 22:56:09 +0000, sln wrote:

> On Thu, 21 Aug 2008 09:11:48 -0500, rpw3 at rpw3.org (Rob Warnock) wrote:
> 
>>sln at netherlands.com> wrote:
>>*IS* raw machine code, *NOT* assembler!!
> [snip]
> 
> I don't see the distinction.
> Just dissasemble it and find out.
>
There's a 1:1 relationship between machine code and assembler. 
Unless its a macro-assembler, of course!
 
> 
> Each op is a routine in microcode.
> That is machine code. Those op routines use machine cycles.
>
Not necessarily. An awful lot of CPU cycles were used before microcode 
was introduced. Mainframes and minis designed before about 1970 didn't 
use or need it and I'm pretty sure that there was no microcode in the 
original 8/16 bit microprocessors either (6800, 6809, 6502, 8080, 8086, 
Z80 and friends).

The number of clock cycles per instruction isn't a guide either. The only 
processors I know that got close to 1 cycle/instruction were all RISC, 
all used large lumps of microcode and were heavily pipelined.

By contrast the ICL 1900 series (3rd generation mainframe, no microcode, 
no pipeline, 24 bit word) averaged 3 clock cycles per instruction. 
Motorola 6800 and 6809 (no microcode or pipelines either, 1 byte fetch) 
average 4 - 5 cycles/instruction.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
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