I have been thinking some on it but the problem I see is they are not trivial to program and require a fair amount of VHDL background. The 68040 and 68360 have been chosen because they can be had in PGA packages which are easily soldered. I have the 68360 in smt (also) and it looks almost impossible to solder without a reflow oven or equivalent. My thoughts now are to introduce some GALs into my designs as they are builder friendly and can be readily programmed with most modern eprom programmers. They will significantly cut down on ttl packages on the boards. FPGAs require jtag hardware to program plus rom to hold the programs as they are not like GALs or other CPLDs. Eventually I might toy with some XC9536's I picked up but again the require a JTAG to program and pretty sophisticated programming/design software though they are builder friendly as they are PLCC 44's. I think this takes most builders out of the piece they like to do (build and debug).
On Sunday, September 16, 2012 7:27:01 PM UTC-5, ..I'd rather be coding ASM! wrote:
This is mostly a tyre-kicking exercise.
I keep watching (and playing) around with the N8VEM systems I've built
(and love!) and a few others such as the V6Z80P which has a whopping great
FPGA in the middle and a 20Mhz Z80. The V6Z80P is a wonderous machine. it
has VGA+AV out, logically a chipset close to an Amiga ECS system with a
blitter, 512kb ram, 512kb video ram, 128kb audio ram, 4-channel sterreo
8bit sound etc.
I've often been a bit torn with how impressive some of the FPGA designs
are yet how enjoyable the non-FPGA's are for their simplicity and ease of
understanding balanced with obtainability of chips.
I was wondering, if people are thinking about using FPGA's for various
"Advanced" designs, and other "complex chips", perhaps there should be a
similar service to the "Here is your blank PCB" that
Andrew/Doug/Sergey/$REST graciously provide where FPGA's are distributed
on a mini-carrier board and have a community designed firmware update
based upon a very small number of reference designs. Ie. Your v1SP3
carrier chip/board can be used with this, that the other SBC project with
different firmware.
For instance, say it was chosen that the Spartan-3 was to be the "common"
FPGA used on a lot of projects. The chip is distributed at near
cost+labour on a carrier board that can go onto the N8VEM project boards
and there is for this small number of reference designs a simple serial
programming method that hobbyists can use to reconfigure the FPGA as
updates become available?
I've been thinking along these lines with the 68040SBC project that uses
the QUICC chips and thinking "I'd desperately love to be able to build one
of these but don't have the equipment to be able to attach one to the
board."
So.. thoughts people? Perhaps a mini-board with the FPGA on it and a
common set of pins underneath that can be socketed for break-out? I'm
still not overly thrilled with the concept of FPGA's, but some projects
are limited without custom ASIC's as many computers were with them even in
the early 80's. (Spectrum ULA, various DEC J-11's when they moved
from bitsliced processors ..etc).
Al.
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Al Boyanich
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