TG68 - The Open Source Minimig CPU into the FPGA

[FrenchShark]

downix wrote:

amigadave wrote:
@freqmax,

I liked your first suggestion much better, and for an A1200 like Minimig, the 32mb RAM should be plenty.  I am sure it is going to take a huge amount of developing effort to get from v1.1 OCS to v3.x AGA w/68020+ soft CPU.  Perhaps as much, or more than Dennis had to put into the whole of his design?  It would be great if a small team of programmers would take it on and speed its completion.  A Minimig that is equivalent to an 030/50mHz A1200 in a small form factor and at a cost of $300 to $450 would be quite an accomplishment.

The FPGA you'd need to fit the 68020 + AGA would run you approx $300 on it's own.  Add in the other parts, you'd likely be nearing $1000.

Give it a few years.  We need to hit ECS before we go AGA, and by that time, prices/density should have come down.  Heck, the chip density used in MiniMig 1.0 would have cost almost $1000 not even 3 years ago IIRC.

I am actually starting this kind of development.
My ultimate goal is to use a Stratix II dev board to create an accelerated AGA Amiga.
Here are the characteristics:
- 32 MB of NOR flash (have already replaced the 16 MB chip by a 32 MB one) -> it will contain the kickstarts and the workbench flash disk.
- 32 MB of DDR SDRAM (64 MB planned) -> it will be the fast RAM
- 2 MB of SSRAM (8MB planned) -> it will be the chip RAM
- Planned (chip and fast) bus speed : 114.5 MHz.
- 100Mb Ethernet
- IDE port
- Stratix 2S60 (3 million gate chip)
- VGA, S-Video, Joy ports, parallel, floppy and keyboard will be on a Santa Cruz daughter board
I want to mount the dev board into an A1200 case with a slim DVD-ROM drive and a compact flash drive.
That will be my dream Amiga :-D

[FrenchShark]

jkonstan wrote:
The Stratix II development board sounds like a nice idea; however, it is really expensive right now ($2K to $3K) unless you have access to one via work or school. Affordable FPGA evaluation boards today, would be Altera Cyclone II/III or Xilinx Spartan 3e.

 :-)

The Nios II boards cost $1000. And only $400 WITHOUT the software (the software is a 1 year licence for Quartus II full version).
The Stratix FPGA are not supported by the Web edition so if you do not have access to a full version of Quartus II, you are limited to the Nios II Cyclone II board or the new E.E.K. Cyclone III.

[FrenchShark]

amigadave wrote:

Sounds like a great plan, are you going to be working alone, or with others to make it a reality?  The reason I ask is that I hope that the huge effort to create AGA and/or 68020+ softcore code is at least done in cooperation and not several individuals working on the same thing at the same time and having it take many times as long to complete as it would if they work together.

I will work alone but of course, I will re-use the nice designs from Dennis and Tobias.
Currently, I am working on a RISC CPU that has the same ALU than a 68000 so I can easily emulate a 68000 with it.
It has a 4-stage pipeline. The Fetch, Decode and Execute stages are almost finished. I am fixing the bugs right now. I need to write the Load/Store unit. The Fmax given by Quartus is 125 MHz.
With a software emulation layer I think I can achieve 5-10 MIPS, if I use some HW acceleration, I can get 10-20 MIPS and maybe with a full HW translator, I can get 100 MIPS.
Even if I do not use it for the main CPU, it can make a nice coprocessor (a la Jaguar) for the audio and video. :-P

[FrenchShark]

TobiFlex wrote:

xmag32 wrote:
don't you think it might be possible to just misuse the rs232 connector for the amiga joystick. I dont'know how many pins of the connector are wired to the fpga.

No chance!
There is no direkt connection between rs232 connector and the FPGA. The rs232 ist connected to a Level Shifter. Remeber the rs232 signals are +/- 12V.
 

IMHO, the best way to connect the mouse/keyboard/joystick is to use an external microcontroller like an SX chip to mux all the I/O signals into one serial link through the PS2 connector.