1 Jul
2014
1 Jul
'14
8:41 p.m.
On 7/1/2014 9:19 PM, David Riley wrote:
On Jul 1, 2014, at 22:33, Mike van Bokhoven <mike
at fenz.net> wrote:
I thought the arcade market would use a small FPGA development board.
Note small is relative here.
So - can anyone explain
the difference, in terms that aren't too hard to understand? And - is
there any hope of modifying a machine that would normally require a
68B09E to be able to use a 68B09?
I believe it's a matter of whether the two-phase clock is
generated internally or externally. The E requires it to be
externally generated, and that's what I'm familiar with; unlike
the 6502, it expects a 90 degree phase shift instead
of 180 degrees. I don't think they're easily interchangeable;
besides the fact that the E and Q pins are outputs on the
non-E version, the LIC and TSC lines are taken up by the
crystal oscillator pins and the DMA pin behaves differently
(not all of this will matter in a pinball controller board, but
at the very least you'll need to make an adaptor board.
My advice, faced with a dwindling supply of pulls (you
used to be able to buy 'em by the bushel from Jameco)
is to consider making a drop-in replacement using
one of the many VHDL/Verilog models now available and
a cheap, tiny FPGA like the MAX II (which Altera likes to
call a CPLD, even though it really isn't) mounted on a
DIP carrier board.
I wonder if there's a market in that for the arcade community...
- Dave
Ben.