Dwayne Dietrich

68000/coldfire difference

Discussion created by Dwayne Dietrich Employee on Apr 1, 2006
Latest reply on Apr 1, 2006 by Dwayne Dietrich
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Aug 24, 2005, 4:48 AM
Post #1 of 17 (276 views)
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 [ColdFire] 68000/coldfire difference  Can't Post 
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right now i implement a 68k system. 68ec000, 128kbyte flash, 256kbyte ram.
this includes to write an assembler. it is more than 50 percent complete.
now, the 68000 is microcode based (the chip contains a microcode table).
can someone list up the difference between 68000/coldfire (in a few lines)?
additionally, i plan to write assemblers for the SH2 (hitachi), and probably even for the pentium. the implementation is in BASIC, and highly relies on tables. additionally, a native version (which can translate itself) is planned for the 68000 board.
the purpose is to write a few demos for the SEGA MEGA DRIVE.
recently i soldered in a PLCC version of the 68ec000, including bending all the pins into flatpack style. for real flatpack, they are too small for manual soldering.
 
Aug 24, 2005, 6:00 AM
Post #2 of 17 (275 views)
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 Re: [ColdFire] 68000/coldfire difference [In reply to]  Can't Post 
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The Coldfire has almost the same programming model as the 68k. There are a
few extra instructions (especially for cores with extra functionality, like
a MAC unit), and it is missing some of the more obtuse addressing modes from
later 68k chips. Otherwise, the real difference between the cores is that
the Coldfire is far more efficient. There are, of course, huge differences
between individual Coldfire chips and a 68000 chip - the ColdFire series are
microcontrollers with lots of built-in peripherals, rather than just a plain
cpu. You'd want to look at the Freescale web site to get summaries of the
different Coldfire micros.
I can't imagine why anyone would write an assembler for the 68000, or the
Coldfire for that matter, unless it is as a learning experiance. There are
many assemblers available, including the excellent open source gnu assembler
(which can be cross-compiled to run on a 68k machine if you want). Most
people would use C or another high-level language, however - again there is
a huge range of tools available.
By the way, it's normal to use a capital letter at the start of sentences in
English - Latin is out of fashion these days.
mvh.,
David
 
 
----- Original Message -----
From: Alex Finn
To:
Sent: Wednesday, August 24, 2005 1:48 PM
Subject: [ColdFire] 68000/coldfire difference

right now i implement a 68k system. 68ec000, 128kbyte flash, 256kbyte ram.
this includes to write an assembler. it is more than 50 percent complete.
now, the 68000 is microcode based (the chip contains a microcode table).
can someone list up the difference between 68000/coldfire (in a few lines)?
additionally, i plan to write assemblers for the SH2 (hitachi), and probably
even for the pentium. the implementation is in BASIC, and highly relies on
tables. additionally, a native version (which can translate itself) is
planned for the 68000 board.
the purpose is to write a few demos for the SEGA MEGA DRIVE.
recently i soldered in a PLCC version of the 68ec000, including bending all
the pins into flatpack style. for real flatpack, they are too small for
manual soldering.

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Aug 24, 2005, 6:09 AM
Post #3 of 17 (275 views)
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 Re: [ColdFire] 68000/coldfire difference [In reply to]  Can't Post 
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thanks for your reply.
about the suggestion to check the freescale site, i did that today.
indeed writing the 68000 assembler prodcued better understanding, now i tend to integrate "microcode tables" into all of my programs.
another issue: the documentation of the sega master system/mega drive are not official releases. the native version allows to write programs on the mega drive itself, and i plan to include a rudimentary programming documentation into the system.
by the way there is a plug'n'play TV set (on the current market), which (i guess) includes a 68000 core. probably it can take any MEGA DRIVE software, however, it does not have a module port.
people notice everything small. however, it is legal latin spelling, and hints for capitalization are hard to find sometimes.
alex.

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Aug 24, 2005, 6:12 AM
Post #4 of 17 (275 views)
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 Re: [ColdFire] 68000/coldfire difference [In reply to]  Can't Post 
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hi,
see my web .......... i think there we could collaborate
tell me about your 68ec000 system
 
-----------------------------------------------
right now i implement a 68k system. 68ec000, 128kbyte flash, 256kbyte
ram..
this includes to write an assembler. it is more than 50 percent
complete.
now, the 68000 is microcode based (the chip contains a microcode
table).
can someone list up the difference between 68000/coldfire (in a few
lines)?
additionally, i plan to write assemblers for the SH2 (hitachi), and
probably even for the pentium. the implementation is in BASIC, and
highly relies on tables. additionally, a native version (which can
translate itself) is planned for the 68000 board.
the purpose is to write a few demos for the SEGA MEGA DRIVE.
recently i soldered in a PLCC version of the 68ec000, including bending
all the pins into flatpack style. for real flatpack, they are too small
for manual soldering.
 
>http://spaces.msn.com/members/afinn23console
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Aug 24, 2005, 8:23 AM
Post #5 of 17 (275 views)
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 Re: [ColdFire] 68000/coldfire difference [In reply to]  Can't Post 
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>The Coldfire has almost the same programming model as the 68k. There are a
>few extra instructions (especially for cores with extra functionality, like
>a MAC unit), and it is missing some of the more obtuse addressing modes from
>later 68k chips. Otherwise, the real difference between the cores is that
>the Coldfire is far more efficient. There are, of course, huge differences
>between individual Coldfire chips and a 68000 chip - the ColdFire series are
>microcontrollers with lots of built-in peripherals, rather than just a plain
>cpu. You'd want to look at the Freescale web site to get summaries of the
>different Coldfire micros.
ColdFire limits its instruction/operand combinations to those that are
no longer than 48 bits. This means that many of the operand
combinations that were valid for the 68k are illegal for ColdFire.
Also most of the ColdFire instructions operate on 32 bit operands,
and have no 8 or 16 bit counterparts like the 68k has.
--
Peter Barada

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Message Edited by Dietrich on 04-03-2006 11:08 AM

Message Edited by Dietrich on 04-04-2006 01:38 PM

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