On 2009-04-29 03:34:37 +0700, Alex Freed <alex_news@mirrow.com> said:
On Apr 28, 11:15 am, Jason <jasonb1...@yahoo.com> wrote:Folks around here seem to be FPGA-happy. Might it not be faster (from a development standpoint) to use an inexpensive PIC or AVR microcontroller to interface an SD card to the //c or is the added flexibility of an FPGA really necessary?This is exactly what my Pseudo Disk did. With an AVR. But to interface directly to the Apple bus rather than to a disk controller which isvery much faster in ProDOS mode a few more chips were needed.However the upcoming CB will take care of multiple thing with a single board and will be extremely flexible.
Alex, correct me if I'm wrong but you're developing mostly for the larger //-series, not the //c-series, right? I read about your efforts to adapt the CB to the //c using a killy clip, but while fine for development purposes, I've read that they are unreliable for long-term use. I gather you can't get all of the signals you need for this off of the expansion slot. :-/
The //c has both a disk interface and an expansion slot. Assuming the SVD is even compatible with the //c, it must use the disk interface. I presume this would limit the speed of operation to that of the original drives -- something like 76.8Kbps, right? This is not fast by today's standards, but would fill 64K of memory in only 8.3 seconds given that there would be no time lost to seeking. With ProDOS, you should be able to create virtual "floppies" of up to 16 megabytes in size as well, right? This seems like a reasonable way to go for //c users without an expansion slot.
-- Jason