Xref: utzoo comp.sys.amiga:47724 rec.games.video:5231
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!texbell!sugar!karl
From: karl@sugar.hackercorp.com (Karl Lehenbauer)
Newsgroups: comp.sys.amiga,rec.games.video
Subject: Re: The Lynx CPU (???)  (Was:Re: Developing for the Lynx)
Message-ID: <4952@sugar.hackercorp.com>
Date: 18 Jan 90 05:41:45 GMT
References: <8581@cbnewsm.ATT.COM> <759@cs.wmich.edu> <7243@lindy.Stanford.EDU>
Reply-To: karl@sugar.hackercorp.com (Karl Lehenbauer)
Distribution: usa
Organization: Sugar Land Unix - Houston
Lines: 39

In article <7243@lindy.Stanford.EDU> unknown@ucscb.UCSC.EDU (The Unknown User) writes:
>>	I didn't find out what language was supported, but a 4 MHz 65C02
>>can compete with an 8 MHz 68000 in execution cycles, so don't sell it short.
>>A few 16 MHz coprocessors don't hurt either.  As far as a simulator, the board
>>executes all the code, so simulation on the Amiga screen isn't needed.

>	Wow, someone's finally giving the 65c02 some credit.

65C02?  That's the fast CMOS 6502, right?  A 6502 with a few new instructions
like zero a register and push x and y, right?  The rest of this article 
assumes that this is the same 65C02 I had on an accelerator card in my ][+ a 
few years back, and not something like the 65816.

Whimper.

Look, the 6502 has, basically, three general purpose registers,
A, X, and Y.  (It also has a status register, program counter and an
eight-bit stack pointer).  You cannot use register indexing to go more
than 256 bytes past an address.  You cannot do indirect addressing unless
the address you want to indirect through resides in the first 256 bytes
of memory.  The stack is limited to 256 bytes.

A MULTIPLY INSTRUCTION??  PSHAW.  On the 6502 you will do it with eight-bit
registers and single bit shifts.  A 16 X 16->32 bit multiply in 6502 assembler
is *pages.*  (It's ONE instruction on the 68000.)

A 16-bit move from memory to memory is four instructions, to do with indirect
addressing requires something like twelve.

Although the 6502 can execute instructions in fewer clock cycles than most
other cruddy old eight-bit CISC microprocessors, those instructions typically
don't do as much.  From a programming standpoint the architecture is so totally 
brain-dead that even an 8080 looks heavenly by comparison.

The scalable sprites and stuff, though, sound really interesting.
-- 
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