alex.freed.007@gmail.com wrote:
On Jan 9, 5:14 pm, mdj <mdj....@gmail.com> 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 ******** Note new website URL ******** NadaNet and AppleCrate II for Apple II parallel computing! Home page: http://home.comcast.net/~mjmahon/ "The wastebasket is our most important design tool--and it's seriously underused."