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Intersystems (FDC-2) Floppy Disk Controller  Card.   

This was the second Ithaca Audio's (later known a Intersystems) Floppy disk controller card card.  Their first one was essentially the Micropolis Board.

Intersystems FDC

The FDC-2 offers the following features:

Up to 4 Mbyte direct access mass storage Single or Double Density
Soft Sector IBM compatible 8" or 5.25" disks, single or double sided 1 thru 4 drives controlled by one boardLSI  controller with extensive instruction set including disk to memory compare instructions.
DMA data transfers between disk and system memory relieve CPU  of cumbersome transfer routines
Efficient  operation  allows entire track contents transferred in one disk revolution
On board EPROM CPM compatibleIEEE 696.2 S-100 compatible including:
    2 or 4 MHz operation;
    8 or 16 bit I/O mapping;
    16 or 24 bit memory mapping for EPROM;
    16 or 24 bit DMA.
In the manual the  FDC-2 may be parsed out into separate functional areas for easier understanding.  These are:-
Disk Controller

This area of the FDC-2 interfaces directly with the disk drives. It can be instructed by the CPU to select one of four drives, move the recording head in .a specified drive to a specified track position, read a specified quantity of data from a drive, write a quantity of data to a drive, format a disk, and even compare data on the disk to system data. The controller also performs CRC checks on all disk data to establish that data's validity.
DMA Controller

This functional area of the FDC-2 is dedicated to the direct transfer of data between the Disk Controller and the user's system memory- The DMA controller has the ability to disable the system CPU asynchronously to program execution, whenever the Disk Controller indicates readiness for data transfer. Once the CPU is disabled the DMA Controller will either read a byte from system memory and send it to the Disk controller, or read a byte from the Disk Controller and write it into system memory. After the DMA transfer, the CPU is re-enabled and will continue program, execution. The user may program the DMA Controller to access any area of an IEEE 696.2 S-1QQ 16Mg address space.

The FDC-2 occupies 16 consecutive locations of system I/O space„ The. function assignment of each of these locations is shown in the FDC-2 Address Map. The user may jumper select the board location at any 16-location boundary in the standard IEEE S-100 64k I/O space. Optionally^ of course, the 8-bit I/O address space may be referenced instead.
Onboard EPROM

Provision is made for a 2708 EPROM on the FDC-2 so that bootstrap firmware for the user's operating system may be located on the board. The EPROM circuitry has its own independent address. The user may jumper-select any 1K location in the extended 16 Mg system memory to locate the EPROM. The board may be configured so that PHANTOM is driven when the EPROM is accessed, thus allowing the FDC-2 EPROM to overlay RAM memory that responds to PHANTOM S-100 line, the EPROM — and the PHANTOM overlaying signal — may be disabled with software. (The EPROM is enabled automatically when power is applied and RESET* goes active.)
The manual for this card can be downloaded here.


Other InterSystems S-100 Boards
64K Dynamic RAM    8K RAM   EPROM   IA-Display   FDC   IO-Card    Z80-Series-II    Z80   ADDA Board   EPROM Burner 
FPB   256K Dynamic RAM   16-64K EPROM
  HDA   Z80-Series_III   6-SIO  EPROM Emulator  RTC Board



This page was last modified on 10/25/2013