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CompuPro - M-Drive
Towards the end of the S-100 bus era "memory disks" became popular. They were equivalent in some respect to today's flash drives.  One of the first came from CompuPro the M-Drive.

CompuPro M-Drive

The M-Drive consisted of 512k bytes of dynamic RAM, a dynamic RAM controller circuit and a method  for addressing the data in the  RAM array. The M-Drive/H looks like two I/O ports to the system bus, it takes up no memory space. One I/O port was used to load a starting address into the board, and the  other  was  used  to read and  write  data. The starting address is actually loaded into a series of counters on the board, and bytes are then transferred in sequence without the need to send a new address for each byte. The counters automatically increment themselves to point to the next  byte.     This  speeds up  transfers  considerably. The counter has 22 bits, 3 more than are needed for 512K bytes. These extra three bits determine which board of eight should send or receive the data.    Thus,  the array seems to the software  like a contiguous 4 megabytes,   instead  of  eight   separate  chunks   of  512k bytes  each.     This  made  the  programming  task  quite  a bit   easier,   as   well   as   using  a   minimum  of  port   addresses. The dynamic RAM controller circuit consists of an Intel 8203-3 dynamic RAM controller and some external logic to permit operation with 512K of RAM. This circuit handles most of the DRAM access functions, as well as providing  the  necessary   refresh  operation  and   arbitration. Since the DRAM is isolated from the IEEE 696/S-100 bus, problems normally associated  with DRAM and  the S-100 bus are  avoided.   
The manual for this board can be obtained here


Other CompuPro S-100 Boards
CPU8085-88  CPU86-87  CPU-Z  Disk1  Disk1A  Disk1B  Disk2  Disk3   EconoROM2708  Interfacer 1  
RAM Boards   Interfacer 3  Interfacer 4  Interfacer II   M-Drive  MPX-Board  PC-Video  
System-Support1  System-Support2   SPIO  Spectrum  SP186   CPU-286
   68000  32016  SPUZ


This page was last modified on 10/25/2013