FDC.TXT  v1.00                                      date : 8-01-91


    The following test material references comes from

    1) the NEC 1981 Catalog for Microcomputers
       or the NEC æPD765,

    2) the 1983 INTEL Microprocessor and Peripheral Handbook
       (referencing the Single/Doule Density Floppy Disk Controller
        or the 8287A),

*** All numbers are in hexidecimal format unless stated otherwise.

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   I O  Port Addresses for the Floppy Disk Controler(s)

Digital_Output_Register    03f2       aka Drive control Register
Main_Status_Register       03f4
Diskette_Data_Register     03f5

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   I O  Bit Register Mapping for differences in the Floppy Disk Controler(s)


Digital_Output_Register    03f2       aka Drive control Register

7 bit Reserved              : 1   Enable Motor for drive 4
6 bit Reserved              : 1      "    "     "    "   3
5 bit Drive B Motor Enble   : 1   0 == off
4 bit Drive A Motor Enble   : 1   0 == off
3 bit Enble Disk DMA        : 1   0 == disable
2 bit Reset Controler       : 1   0 == Reset
1 bit Reserved              : 1   Drive Select Bits for Drive 3 & 4
0 bit Disk Select           : 1   0 == Drive A ; Least Significant Bit


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Main_Status_Register       03f4
This is a read only register.

7 bit RequestMaster         : 1   1 == REQUEST to FDC is OK */
6 bit DataDirection         : 1   1 == Data to be read; 0 = write data OK */
5 bit DMAMode               : 1   0 == DMA mode Enabled */
4 bit FDCBusy               : 1   1 == FDC has command in progress */
3 bit Drv3Seek              : 1   1 == Drive3 seeking */
2 bit Drv2Seek              : 1   1 == Drive2    "    */
1 bit Drv1Seek              : 1   1 == Drive1    "    */
0 bit Drv0Seek              : 1   1 == Drive0    "; Least Significant Bit */


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The normal status of a Floppy Disk Controller is 1000 0000b (binary).

The reset status of a Floppy Disk Controller is 0000 0000b (binary).

Command in Progress status is 0001 0000b (binary).

Drive 0 seeking is 0000 0001b (binary), but
it may be 0001 0001b (binary) at times.