ULMO031@FRORS12.BITNET (11/26/88)
Date: 25 November 1988, 21:27:30 EDT
From: Raynaud (1) 47 02 03 55 ULMO031 at FRORS12
Well, many things have been said about that subject. I'd like to give
my opinion, so here it is. But first, please note that this is a 'sensible
subject' for you Apple II guys, you can't usually stand Mac people.
The 65816 is a 16 bits processor. It is normal that it uses 8 bits
for an instruction opcode.
The 68000 is a 32 bits processor, so it uses 16 bits for an
instruction opcode, right.
It is wrong to say you can't have array of more than 32Ko. This is
only right for that IBM program called Turbo Pascal which is supposed to
compile Pascal (and in fact knows only about Basic). You can have an array
of 500 Ko if you like, with NO problem of segmentation.
I would say (forget about the clock speeds) that a 65816 is as good
as a 68000 when it has to treat 16 bits data.
I wouldn't say the zero page of the 65816 corresponds to registers
because to access them, you have to get TWO things from memory (where in
the zero page, and then you get the zero page itself) whereas when you use
real registers, you only have to get the number of it (the access is
faster).
But when you are in a loop, it is much easier (and faster) to have 16
registers (in fact 13 for the Mac) than only 3. I let you imagine what
would happen if you had to work with longs or do maths (MUL or DIV). This
is why I think the 68000 is faster than the 65816. But there are other
reasons : the 68000 allows debugging. You can step, and things like that.
It is hard coded, and very pleasant to use. Also, with the 68020, you can
have coprocessors. And once again, it is very well designed : a
coprocessor just adds new instructions, and it is EXACTLY as if they were
instructions of the main processor. So, with the 68881, you add FSIN,
FCOS, FSQRT, etc... and it is transparent to the programmer, and fast.
Let me tell you one thing : debugging with a 68020 is really a
pleasure.
I also have an Apple II and I am very happy with it. For a
programmer, the main goal is to program, not to look at the chips of his
neighboor. You can enjoy your 65816 really. But do not think it is better
than a 68000. The 65816 has to emulate a 6502, which is a pain for a
modern processor.
Before saying that, I have used both Apple and Mac. I also enjoy
electronics so I can have some ideas about time access and other things
like that.
Alain Raynaud
<ULMO031@FRORS12. BITNET>u546457684ea@deneb.ucdavis.edu (0040;0000004133;0;1;141;) (12/15/88)
How would I get onto the applelink on this unix system?
Any information would be appreciated.
Richard Joe