Date   : Tue, 17 Jun 1986 10:49:15 CDT
From   : Jeff Henkels <F1.JJH%ISUMVS.BITNET@wiscvm.ARPA>
Subject: RAM disk question

I am considering building a RAM disk for my S-100 system.
Because my Z-80 CPU board does not have the IEEE 24-bit
addressing or bank switching, I will have to the access the
RAM disk through I/O ports (the way CompuPro's M-Drive/H does).

However, I don't understand how the memory is addressed on the
RAM disk.  If the board is accessed only through I/O ports,
how is the on-board memory address generated?  A regular S-100
address decode circuit won't work, because the RAM disk is
not in the system memory space.  Does the address have
to be calculated by the CP/M BIOS and then written into latches
on the board, or is the calculation done on board given "track"
and "sector" information?

Any help you can give me would be greatly appreciated.


                            Jeff Henkels
                            F1.JJH@ISUMVS.BITNET@WISCVM.ARPA