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Re: [N8VEM-S100:6022] Dual IDE/CF V2a

Rich and Gary,

>> Good points - my Z80 CPU is a decades old Compupro CPU-Z with a vintage Z80 running at rated
>> 6 MHz - nothing fancy there.

One of the CPU cards I've tried is the CompuPro CPU-Z, but at 4 MHz.  I even tried turning on I/O wait states, but nothing changed.  I also tried to get the IDE/CF card to work with a Cromemco ZPU.  Same problems.

>> The card manufacturer is worth looking at. I have  been using a 256 MB Sandisk card.

I've tried a number of different CF modules.  In frustration, I bought some of the 4 GB Kingstons pictured on John's build page (the ones with the white flowers on them).  Didn't change anything.

>> What bothers me about this discussion is that other IDE-CF interfaces appear to work
>> without problems - for example John Coffman's ECB SBC Mk IV works with anything I
>> have thrown at it with no issues. Same for my digital cameras that work flawlessly with
>> any CF card I have tried. Something about this S100 board is marginal.

Well .... I've designed and built 2 different Z80 SBC's with CF interfaces, and both work flawlessly.  On both, the CF interface is directly on the Z80 bus signals (no 8255).  Both run at 10 MHz.  I have even designed and built a 68k SBC (again, running at 10 MHz).  On the 68k, I was forced to use an 8255 because I couldn't figure out how to utilize the raw 68k bus signals for the CF.  The biggest problem is that the 68k R/W* signal isn't a pulse as such, it just switches level.  The 68k CF works flawlessly too, but I'm still in the process of trying to figure out how to get CP/M 68k up on it.  Everything I've tried with the 68k CF seems to work well ... so far.

No worries -- my efforts to build a "diskless" S-100 system continues.  I have designed and built an S-100 RAMdrive.  It is 4 MB, and battery backed.  It looks like 4 ports to the S-100 bus.  Without the latency of rotational media, even a 4 MHz Z80 is quite responsive.  I use the second serial port of the N8VEM serial card to access a UDrive, and I can read and write files from/to that.  No floppies or hard drives required.  BTW, that serial card is a real "keeper" -- excellent, once you figure out the serial port headers.  I can run a very nice S-100 system with just a cpu card, 64k memory card, the above mentioned serial card, and my RAMdrive.  I'd love to have an IDE/CF card working, but it appears that won't happen.  Anyone who might be interested in any of this can see the 68k and RAMdrive projects on my Web site:  www.hanscom.us.