alex.freed.007{at}gmail.com wrote:
> On Jan 9, 5:14 pm, mdj  wrote:
>> Either of those are more than adequate solutions for the z80 card. I
>> imagine though that an integrated solution would make more sense on
>> the generic FPGA card, since this would make it easy to ship
>> 'customisers' + FPGA firmware that could be installed and activated on
>> the Apple II without needing any additional tools.
>>
>> This would lif the appeal of the device to 'consumer class' instead of
>> just 'hacker class'. Well worth the couple of extra SOIC's or tiny
>> CPLD the addition would require.
>>
> 
> My thoughts exactly. We'll most likely add a few gates to assess the
> JTAG lines from the apple bus, but it may not be very practical. The
> ".bit" configuration file doesn't even fit on an Apple floppy and
> somebody needs to port the Xilinx programming application to Apple.
> 
> Considering that a parallel JTAG cable is $12 from Digilent and $6 on
> ebay ("buy now"), using that to load a different downloaded
> configuration
> may be much easier.

But it's like the difference between a plug-board programmed computer
and a stored-program computer.  ;-)

If the Apple could dynamically reconfigure the FPGA card, it would
make it truly a different substance.

The practical issues of configuration file size and programming speed
are, of course, of real importance.  I was about to ask what a typical
file size is...  And how many bits must be banged per "bit" of config?
And are there real-time constraints--for example, can the programming
be "paused" and resumed after a disk I/O?

Config files up to a megabyte are certainly supportable with CFs and
other "hard disks", but just how much config state is there, really?
(I thought all this used to go into a nearby ROM.  ;-)

-michael

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