68k homebuilts

Sridhar Ayengar ploopster at gmail.com
Mon Dec 15 13:44:35 CST 2008


bfranchuk at jetnet.ab.ca wrote:
> der Mouse wrote:
>>> How do you have RISC from a CPLD since RISC implies a large register
>>> stack?
>>>     
>>
>> It does?  I thought it implied a (moderately) minimalist instruction
>> set.  This tends to correlate with having lots of registers, but that's
>> hardly necessary - consider the PDP-8, for example.
>>
>>   
> The idea of a RISC is that out of few general addressing modes
> ( to keep decoding simple ) you generate all the other needed
> ones in software. Since decoding is so simple you can ran faster by 
> pipelining
> everything and goes real fast, providing *gotya* main memory is that fast
> too.

But again, none of those performance enhancement strategies are 
*required* to be in a RISC chip.

Peace...  Sridhar



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