25 Jun
2007
25 Jun
'07
9:52 a.m.
On 22/06/07, Chuck Guzis <cclist at sydex.com> wrote:
The GI CP-1600 16-bit CPU had an architecture very
similar to the PDP-
11, but used a 10-bit instruction word. I think GI even marketed 10
bit ROMs. These were used in various incarnations as the CPU in many
Activision consoles.
Since a few people have picked up on this, I've done a bit of
Googling. Everywhere seems to say that it was a fairly vanilla 16-bit
CPU, it just had 10-bit opcodes, so Intellivision used 10-bit memory
in the cartridges. 10 bits is a "deckle", apparently.
http://en.wikipedia.org/wiki/Intellivision
<<
Intellivision was the first 16-bit game console, though some people
have mistakenly referred to it as a 10-bit system because the CPU's
instruction set and game cartridges are 10 bits wide. A 10-bit chunk
of data is called a "decle". The registers in the microprocessor,
where the mathematical logic is processed, were 16 bits wide.
>
http://www.intellivisionlives.com/bluesky/hardware/intelli_tech.html#cpu
<<
CPU
The CPU is the General Instruments CP1610. This is a general purpose
16-bit microprocessor which has 1024 separate op-codes, and can
equally well use 8-bit, 10-bit, 14-bit, and 16-bit RAM or ROM. The
CP1610 in the Intellivision uses a machine cycle rate of 894.886 KHz.
Individual operations on the 1610 take between 4 and 12 microcycles
(Note: the CP1600 is the prototypical or conventional form of the
microprocessor; the CP1610 used in the Intellivision is precisely the
same in all respects except for a differing clock rate.)
Since most 1610 instructions are 10-bits wide, game programs are
stored in 10-bit wide ROMs. This 10-bit "byte" is referred to as a
decle (rhymes with "heckle"). Some instructions require 16 bits; these
are stored in two successive 10-bit locations, referred to as a
bidecle. (For prototyping, dual 8-bit EPROMs are used, with the low 8
bits of each decle stored in one EPROM and the top 2 bits stored in
the other.)
>
And the fairly detailed overview at:
http://intelliwiki.kylesblog.com/index.php/CP1610
--
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