Editing RTL m68k

Is there a "soft core" m68k for [[FPGA]]s?

Haveing the cpu in vhdl/verilog would allow to eliminate the need for a special [[Minimig]] board. And being able to use plain developer boards from Xilinx or other manufactors.

''Have you seen the [http://www.opencores.org/forums.cgi/cores/2000/03/00281 discussion at Open Cores]?''

The most finished 68000 in VHDL I know of is from the Atari ST in VHDL:
[http://download.experiment-s.de/Suska/Configware/2K7A/rtl/vhdl/WF_68K00_IP/ Suska project : 68000 IP v2K7A]

: Would it make any sense to replace the "FPGA chip + CPU chip" on the current Minimig, with a single-chip "FPGA + CPU chip" device? --[[User:DavidCary|DavidCary]] 21:28, 28 July 2007 (PDT)

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The [http://www.bigmessowires.com/plus-too/ Plus Too project] is a working hardware replica of the Macintosh Plus and Macintosh 512Ke computers. The project’s goal is to recreate these classic computers using modern electronic components, producing a stand-alone machine able to run period Macintosh software from the mid-1980′s.
It replaces the original Motorola 68000 CPU with a soft-CPU module within a FPGA
(although a future version will probably use a real 68000 CPU).
It replaces the original floppy drives with a SD card interface.

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The FPGA HP98x6 project includes a
[https://sites.google.com/site/olivier2smet2/hp_projects/hp98x6/fpga-hp98x6 68000 soft core].

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[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=39358&forum=8&viewmode=flat&order=ASC&start=8#forumpost465986 TobiFlex 070826 13:39]<br>
This CPU Core is not finish. The Debuging must go on. Currently hangs up this CPU Core with Kickstartrom 2.04 at #$F81914.

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=39358&forum=8&viewmode=flat&order=ASC&start=8#forumpost465988 TobiFlex 070826 14:06]<br>
I have adapted the minimig Core to the DE2 Board from Terasic with a ALTERA Cyclone 2C35. With an external CPU MC68HC000 runs the Minimig perfekt. I have change the RAM Timing from SRAM to SDRAM - so i can use the on Board SDRAM Chip.
And now i use the Board to Debug Wolfgangs 68K Core.

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=39358&forum=8&viewmode=flat&order=ASC&start=8#forumpost466035 mongo 070826 20:25]<br>
Wolfgang's 68K core will run up to about 17 MHz in a Spartan 3.

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=39358&forum=8&viewmode=flat&order=ASC&start=8#forumpost466058 jkonstan 070826 21:23]<br>
external CBT16245 level shifters

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8#forumpost484540 TobiFlex 071126 13:49]
:TobiFlex releases his [http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8#forumpost484540 TG68] MC68000 project source code in [[VHDL]]. With a size of 3000 lines.
:"The Kernal is 2x-3x faster then the 68000 with the same clock and you can clock them with 28MHz.
I think it is possible to make the minimig 8x-12x faster then the original."
:Is there any attempt to make the instruction timings the same as the original 68k?
::Most of the byte and word instructions are exact. Long and mulu/divu/rotation instructions are faster.

:The MC68EC000 is different from the 68000. I have my Core let run against a real MC68HC000 and can not :find software differences when the Kickstart or some programms are running. So I know all importand :Instructions works correct. About never used Instructions I can not say anything.
:Example: I have found no program for the AMIGA that use CHK or MOVEP Instructions.

:About the doc on the second link. My Core use no prefetch. My Core use classical Fetch/Execute last - :Decode - Fetch next/Execute - order.
:Thats why most Instrucions can execute in 2 clocks. The Bus wrapper expand this to 4 clocks.
:But for the minimig is the prefetch not so important. The core is fast enough to decode the opcode between as=high. So the timing is the same as the 68000 timing.

:On my DE2 Board with a real MC68EC000 and running ANARCHY1 DEMO I can see some rendering error but with the softcore I can not.
:I dont know what happens but I think my core has a high Betatested Level. (Upss I hope you can understood my - sorry for my poor english)

:OPCODE 0x0F0E MOVEP.W ..... My Validator stop here. 

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8#forumpost484540 billt  071126 15:57]
:Simulators
:: http://www.symphonyeda.com/proddownloads.htm
:: http://ghdl.free.fr/
:: http://freehdl.seul.org/


[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8#forumpost484540 alexh 071126 16:14]
:There are some subtle undocumented 68k behaviour that you might be interested in:
::http://www.trzy.org/files/68knotes.txt
::http://pasti.fxatari.com/68kdocs/
:Testdisc known to be sensitive to 68000 incompatibility: http://amiga.nvg.org/warlock/adf/b/Birk+Sundell/100C64Tunes.adf.gz

[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&post_id=484583&order=0&viewmode=flat&pid=0&forum=8#forumpost484583 Dennis 071126 19:48]
:Quick compile using webpack 6.3.03i:
:Device utilization summary:
:---------------------------
:
:Selected Device : 3s400pq208-4
:
:Number of Slices: 2627 out of 3584 73%
:Number of Slice Flip Flops: 1052 out of 7168 14%
:Number of 4 input LUTs: 4841 out of 7168 67%
:Number of bonded IOBs: 74 out of 141 52%
:Number of GCLKs: 1 out of 8 12%


:=========================================================================
:TIMING REPORT

:NOTE: THESE TIMING NUMBERS ARE ONLY A SYNTHESIS ESTIMATE. FOR ACCURATE TIMING INFORMATION PLEASE REFER TO THE TRACE REPORT GENERATED AFTER PLACE-and-ROUTE.

:Timing Summary:
:---------------
:Speed Grade: -4

:Minimum period: 39.906ns (Maximum Frequency: 25.059MHz)
:Minimum input arrival time before clock: 16.900ns
:Maximum output required time after clock: 16.576ns
:Maximum combinational path delay: No path found

:I need a bigger FPGA :-)
@@ Line 54: / Line 54: @@
 :OPCODE 0x0F0E MOVEP.W ..... My Validator stop here.
-Boards:
-:http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&No=83
-:http://www.altera.com/products/devkits/altera/kit-cyc2-2C20N.html
 [http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8#forumpost484540 billt  071126 15:57]
@@ Line 101: / Line 97: @@
 :I need a bigger FPGA :-)
-[http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=41728&forum=8&viewmode=flat&order=ASC&start=20 karsten 071126 20:02]
-:Days of Thunder uses the CHK instruction: http://eab.abime.net/showthread.php?t=1144