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SemiDisk Systems --  History
There were a number of different type of SemiDisk Boards. Going from a memory capacity of 512K to 1MB of RAM for the SemiDisk I series all the way up to 2MB for the SemiDisk-II series.

SemiDisk II

What was nice about the boards was that they offered excellent software drivers to run under CPM 2.2 or CPM 3.0 that quickly allowed you to have a system up and running in almost minutes. 

The board was IO/mapped on to the bus.   It had track and sector registers which you wrote to, and the hardware on the board mapped the data into the memory array. A similar system was found in the Electralogics board. It was very fast and made software writing a snap, to the point that the byte count in the sectors was automatically incremented each time your wrote to it.
Unfortunately I do not currently have a manual for either the SemiDisk I or SemiDisk II boards.  If you have one please let me know.
Bill Machrone compared this board to some others in an article in the January 1983 issue of Microsystems (Vol 4, #1, p78).  It can be seen here.


SemiDisk  S-100 Boards

This page was last modified on 10/25/2013