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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: ThomasML on August 30, 2007, 12:44:18 AM
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What's the difference between the various 68xxx-series available today (the original 68000-series is hard to get without ordering larger quantities, it seems). Can one use 68333 instead of the 68000 for the minimig, what would be the implications?
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Thomas
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Without digging too deeply in to freescale's document library, they arn't 100 % compatible. Digikey.com shows the part availabe but in only large quantities. Anyone else have a source?
Plaz
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ThomasML wrote:
What's the difference between the various 68xxx-series available today (the original 68000-series is hard to get without ordering larger quantities, it seems). Can one use 68333 instead of the 68000 for the minimig, what would be the implications?
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Thomas
68306 is a microcontroller with a 68000 core, DRAM controller, GPIO, DUART, 5V I/O, etc ...
683xx CPU32 core:
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- M68000 Opcode Compatibility
- Selected M68010 Enhancements (Virtual Memory, Vector Base Register, Loop Mode)
- Selected M68020 Enhancements (Addressing Modes, Instructions)
-BDM/JTAG CPU core debugging capable.
68331 is a microcontroller with on chip SRAM a CPU32 core (CPU32 = stripped down 68020 instruction set), 5V I/O, A/D, GPT timer, SPI, and SCI.
68332 is a microcontroller with on chip SRAM with a CPU32 core (CPU32 = stripped down 68020 instruction set), 5V I/O, TPU, A/D, SPI, and SCI.
68333 is a microcontroller with on chip SRAM and on chip FLASH with a CPU32 core (CPU32 = stripped down 68020 instruction set),5V I/O, TPU, SCI.
68376 is a microcontroller with on chip SRAM with a CPU32 core (CPU32 = stripped down 68020 instruction set), 5V I/O, A/D, TPU, and dual CAN controllers.
With enough work, all of these can be used for MiniMIG.
etc ....
:-)
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http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MC68SEC000AA16-ND
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AFAIK the 68000 opcode compatibility is for user mode only. The supervisor mode is different to 68000, and that could pose some problems. For example stack frames are different.
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Piru wrote:
AFAIK the 68000 opcode compatibility is for user mode only. The supervisor mode is different to 68000, and that could pose some problems. For example stack frames are different.
Piru, Good point on CPU32 Supervisor mode ...
Supervisor Stack frame could cause compatibilty issues.
Thus, 68306 (68000 CPU core, Not CPU32) would be the most compatible from the group of integrated processors/microcontrollers.
:-)
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http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MC68SEC000AA16-ND
So are you suggesting getting the 16mhz version and overclocking?
Plaz
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There is no overclocking of a 16Mhz 68SEC000 CPU on MiniMIG1.
68SEC000 CPU core is clocked at 7.09379MHz from Spartan3 FPGA DCM.
:-)
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68SEC000 CPU core is clocked at 7.09379MHz from Spartan3 FPGA DCM.
Ah, excellent. For what ever reason I was assuming 20 just from the part number listed on the 1.1 schematics. Clearly 3 hours of sleep wasn't enough last night.
Plaz
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I'm finding it hard to source the Freescale 68k SMT versions from here in Australia and dont want to commit to say 36 of them and have expensive freight from America.
Have been thinking about fabricating my own boards adding in my own modification so I can use the original DIL Motorola CPU. hmmmmm not so elegant in size. :-(
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Ok, after reading on Freescale's website, and looking at digikey once again, I found that MC68SEC000AA16 is available with a min. quantity of 1. Someone said that the MC68k on the minimig was running at 7MHz, and if that's the case then the above MC68k should do, right?
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Thomas
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ThomasML wrote:
Ok, after reading on Freescale's website, and looking at digikey once again, I found that MC68SEC000AA16 is available with a min. quantity of 1. Someone said that the MC68k on the minimig was running at 7MHz, and if that's the case then the above MC68k should do, right?
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Thomas
Correct, MC68SEC000AA16 CPU core would be clocked at 7.09379MHz from Spartan3 FPGA DCM.
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Great news, then I'll start collecting a BOM and making a PCB-layout with a 12cm x 12cm board, and pinheaders instead of PS/2, DSUB-connecters, etc.
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Thomas
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Where is the community spirit here?
One person agree to buy say 84 of the buggers (or whatever the minimum order is) and the others agree to buy them off them ;-)
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I see 5 Volt levels and instruction incompabilities as major obstacles to use the 683xx chips. Maybe instruction incompabilites can be hidded by the FPGA ..?
As for a better cpu, I found this at digikey:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MC68060RC50-ND
MC68060RC50-ND
520.31000 USD
3.3V
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MC68030FE20C-ND
MC68030FE20C-ND
49.47267 USD
5V
EC = No FPU, No MMU
LC = No FPU
http://en.wikipedia.org/wiki/M68k - Generation overview