Subject: Proposed to comp.arch

From: Bill Broadley <[email-masked]>
Date: Mon, 28 Jun 1993 06:28:32 -0500 (EDT)

I was thinking of posting this with 2 goals: Explore any other options for
cpu, and get more people interested in design, and purchase of the board.
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Subject: Best cpu under $300

I'm looking for the best cpu to put in a motherboard to be designed for a 
small quantity production run (say between 25-100) to run a free unix port.  

Mandatory considerations: 
   Maximum to memory cpu speed 40 Mhz (for ease of design)
   Must run gcc (for easy of porting a free unix).
   Around $300 or less in quantity of 25-100  (going for a < $700 motherboard)

How do I define best?  
	Maximizing speed (specint, specfp) 
	minimizing cost/complexity of the implementation.  
	Cleaness of design/architecture.
	Ease of programming.

Optional floating point would be great for those who can't afford it.
 
So this probably rules out any Mips 4000, Alpha, Pentium chips on cost alone.

I've heard that the i860 and i960 are tough to program, and I don't like the 
design of the 486.

Post or email.
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Optionally:

If you interested in the design of the motherboard send a subscribe to 
[email-masked]

-- 
Bill					1st>	[email-masked]
[email-masked] <2nd 	3rd> 	             [email-masked]
Linux is great.         Bike to live, live to bike.                      PGP-ok

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From: Bill Broadley <[email-masked]>
Date: Mon, 28 Jun 1993 08:56:14 -0500 (EDT)

> 
> Your post to Comp.arch mentioned the I960 as "hard to program".
> This is not true. The 960 has a clean architecture, and has a GCC 
> port.
> 
> 				Roger.

Hmmm I heard several things that make it unattractive for programming
in unix.  (which I kinda believe because nobody uses it for unix).

Does it do context switching well?  I have heard things like mult a,b,c
Multiplies a*b and puts the answer from 3 multiplies ago in c.

It's supposed to be very fast (at least in fp) but very hard to
extract that performance.  Any info would be appreciated.

There's an i860 port for gcc also.

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From: Bill Broadley <[email-masked]>
Date: Mon, 28 Jun 1993 09:54:27 -0500 (EDT)

> 
> The pipeline in software (mul a,b,c -> result from two multiplies back in
> c) is an '860 "feature".
Ahh I guess I got confused...

> 
> The '960 is inattractive for a Unix implementation. In that you are right.
> 
Well thats definitely the target, I change the wording thanks.

> The different versions of the '960 have either a MMU, FP or a Super Scalar
> version. No two of these go together (I think... I use the Super Scalar
> version: the I960 CA). For Unix you need all three. (The military
> is able to get two of them.....)
> 
I'd guess FP and Superscaler.  No need for MMU.