Thanks Tom, So it looks like SD cards (in any form) are slower than CDF cards. Did not really appreciate that and is good to know. Thanks. On the CF card interface, I’m missing how a PIC32 (or any microprocessor) as a bridge on the S100 bus would in fact be faster that “straight” 74Fxx style buffers/latches to get 8 or 16 bit data in and out of the CF card registers. Currently I’m thinking of multiple 74F374 style latches interfacing directly to the CF card data lines and on to the S100 bus. In essence it would be emulating the 8255 in 74Fxx TTL fast logic. Even at that, I’m wondering if all of this could in fact save me a wait state. The only way I can see a microprocessor being faster in between the “ two busses” would be that it internally buffers multiple sectors and later writes them to the CF card. Reads I cannot see an advantage unless we do track reads assuming a decent number of sequential sector reads. The one lesson I learned way back with that Propeller Console IO board is that the S100 bus generated pDBIN and pWR* signals are in fact very short. Too short for another microprocessor to do anything useful and definitely too fast for a high level language. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Tom Lafleur Maybe if you re-do that board, you do a dual CF/SD card board... Instead of an Z80, use a PIC32... VERY FAST, SD driver available in C, should be-able to find CF drivers... Inherent timing is available on the chip.. less, board space than Z80.. simple to program... On Thu, Oct 1, 2015 at 10:06 AM, John Monahan <mon...@vitasoft.org> wrote: I Agree Tom, I would like as far as possible to keep the hardware transparent to the software. I think even the 82C55 is the bottleneck. I’m wondering if I should put in a fast (10MhZ) Z80/ROM/ROM chip set and buffer data to/from the CF cards or as Dave suggests do a 74Fxx/GAL hardware equivalent of the 82C55. Any suggestions for a really fast onboard CPU that has RAM/ROM and the capability of having 3 I/O ports in a circuit. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Tom Lafleur One of the issue I have is that we have a number of 8080/z80/cpm/mpm projects on many different platform, all use a mix of SD (most of them) and CF cards.. John's CF board Josh 8080 board SD card Grants cyclone IV board SD Card Waynes Zeta Board SD Card Others... It would be nice if we has a standard so that a card on one would work on another system.. at lease at file interchange level, not necessary boot level also, john's current CF board is NOT tolerant of many well known brands of CF cards... If a new design is done, it should allow use of most any CF cards, or what John is proposing, moving on to a more common SD card.... thanks On Thu, Oct 1, 2015 at 8:56 AM, David Fry <dgf...@googlemail.com> wrote: Hi Alex, then I think my second point becomes the relevant point. Would it be possible to develop a discrete logic replacement circuit to achieve higher performance and allow continued use of CF media and the current CF media imaging process with cpmtools. regards David
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