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- Path: sparky!uunet!sun-barr!apple!apple!netcomsv!mork!mcmahan
- From: mcmahan@netcom.com (Dave Mc Mahan)
- Newsgroups: comp.sys.m68k
- Subject: Re: Simple, ignorant question.
- Message-ID: <szfmc9.mcmahan@netcom.com>
- Date: 22 Jul 92 16:39:00 GMT
- References: <83786@netnews.upenn.edu>
- Organization: Dave McMahan @ NetCom Services
- Lines: 42
-
-
- In a previous article, magsman@cattell.psych.upenn.edu (Madeleine Schneider) writes:
- >so what computers and devices use 683xx processors, and what
- >is (in simple terms) the difference from the 680xx family?
-
- As stated previously, the 68xxx family CPU types are general purpose. They
- require a fair amount of support logic in addition to the CPU for proper
- operation. They are capable of (probably) more throughput in general
- classes of computation, but they cost more to implement because of the
- extra glue chips required.
-
- The 683xx family of processors is intended for embedded applications. They
- can be used as general purpose processors, but where they really shine is
- when they are used in a place that has a dedicated need for a CPU (i.e.-
- they aren't going to execute just any old program somebody types in) and
- the designer wants to avoid having to build a 100 square inch board to do
- something. The 683xx processors were designed so that you don't need tons
- of extra support chips to get going. The 68332 was originally designed to
- be placed into an automotive environment and do things like control engine
- timing, transmission control, etc. To get it running, about all you
- really need is one crystal, the CPU, some pullup resistors, and a 16-bit
- wide EPROM. The chip comes with a minimum amount of RAM (2 Kbytes) on
- board that allow you to place some program variables and the stack within
- it. If you want more RAM, all you have to do is add the RAM chips.
- Decoding and chip-selection is supported by the CPU chip directly. The
- 68332 also has lots of little extra things to make life easier. It comes
- with a periodic timer so you can track passage of time, synchronous serial
- ports so you can easily communicate with things like A/D converters without
- lots of extra parts or wide data busses, chip-select logic so you can
- easily add extra RAM or ROM without having to build up entire DTACK
- circuits, an RS-232 compatible async port that provides digital logic
- signals for RS-232 connection (you supply a logic-to-RS232 level
- converter), an on-board PLL so you can use a cheap 32 Khz watch crystal to
- create a CPU frequency of up to 16 MHz, etc.
-
- >maggie : magsman@cattell.psych.upenn.edu
-
- -dave
-
- --
- Dave McMahan mcmahan@netcom.com
- {apple,amdahl,claris}!netcom!mcmahan
-