
The KK Computer: A Radical 6502 Redesign - peter_d_sherman
http://laughtonelectronics.com/Arcana/KimKlone/Kimklone_short_summary.html
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peter_d_sherman
Excerpt:

What Can It Do?

"The main feature is fast access to a flat, 24- bit address space. [This is on
an 1980's, 64K max, 8-bit microprocessor!] Although there are many ways to
retrofit a 'C02 with expanded memory, AFAIK none can touch this implementation
for speed. Given any random address in the 16 megabyte space, KK can fetch
that byte in 6-8 cyles. It's fast because:

the extended addressing is part of the instruction set. There's no MMU to
spoon-feed. memory is organized as blocks of 64K (not a fraction thereof, such
as 16K) Units of 64K make it easy to treat the entire memory as a linear, 16
megabyte space. That's because the results of address arithmetic — a 24-bit
addition, for example — are directly acceptable by the machine. The most-
significant byte is the block address. This is far more efficient than a
scheme using, say, 16K blocks because a 16K-block system needs to mask and
shift the addition result to isolate the block address before it can be passed
to the hardware. Efficient linear addressing opens the door to a modest range
of "big data" applications — tasks which would cause most expanded- memory
8-bit machines to hit the wall. They suffer an order- of- magnitude speed
disadvantage simulating a linear space."

