Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!sun!amdahl!netcom!mcmahan
From: mcmahan@netcom.UUCP (Dave Mc Mahan)
Newsgroups: comp.sys.m68k
Subject: Re: 68332 with MMU
Message-ID: <16849@netcom.UUCP>
Date: 15 Nov 90 07:46:39 GMT
References: <11249@goofy.Apple.COM>
Organization: Dave McMahan @ NetCom Services
Lines: 62


 In a previous article, keithley@applelink.apple.com (Craig Keithley) writes:
>68340 doesn't have a MMU.   Dual channel DMA, dual UARTS
>68332 has a TPU (Timing Processing Unit -  REALLY great for automotive 
>apps)

It was designed due to the automotive applications market, but it is also
quite useful outside that arena.  I'm using it in a medical data transmission
product to gather data (heart information, ECGs and such) from an implanted
defibrillator made by the company I work for.  The data will be sent via
phone modem to the doctor for analysis.  The TPU is ideal for everything
from debouncing pushbuttons to generating unique pulse timing waveforms that
carry PWM data to our device implanted within the body.


>68331 no TPU (cheaper than a 332 )

I think this part does have a TPU, but it as only 8 seperate channels instead
of the 16 channels provided by the 332.  It seems that Motorola is pushing 
this part more heavily in the advertising (as compared to the 332) but that
could be just because it is newer and needs more exposure.

>68302  I forget... Anybody remember?

This chip has various hardware that is useful for decoding digital telecom
data lines such as ISDN, CEPT, and LAN standards.  I believe it is mainly
intended for connection to a high speed digital serial data line (using one
of the standards) and decoding and encoding desired channels of data.

>The 340 has a "background debug mode" implemented in IPU microcode.  
>Instruction execution is suspended when the 340 is in background mode.  
>Using the debug serial I/O port you can change registers, examine memory, 
>etc without needing a debug monitor.

The 332 also has this feature.  I would bet that the 331 also has it, but I
don't know for sure.  The documentation from Motorola "strongly recommends"
that any design for the 332 include the ability to access this feature.  All
you really need to do is put an 8 position header on your product that makes
certain pins of the CPU available in a convienient fashion.


>My only complaint about the 683xx series is that they are too expensive 
>right now. 

This is quite true.  I think the 68332 is down to around $180 or so now.  About
8 weeks ago, it was priced at about $260 from a distributor we deal with.  Of
course, this $260 amount was for sample quantities of 2 so may be slightly
inflated.  The other complaint I have is that you have to buy a minimum of
one tray.  A tray is 36 parts.  Quite a large cash outlay for prototype work.
If you want to do volume surface mount production, a tray of parts is no
big deal.  For designing the product, though, it's a bit steep.  I was told
back in late August or early September that the 332 should cost about $30 by
the end of 1Q91.  We will see if they hit that target.

>Craig Keithley, Apple Computer
>keithley@applelink.apple.com 

   -dave

-- 
Dave McMahan                            mcmahan@netcom.uucp
					{apple,amdahl,claris}!netcom!mcmahan