--------------------------- There are 15 commands which the FDC uPD765a wil execute.Each of these commands require multiple 8-bytes to fully specify the operation which the processor wishes the FDC to perform. --------------------------- The following commands are available : --------------------------- 00 - INVALID 01 - INVALID --------------------------- 02 - FDC_COMMAND_READ_A_TRACK --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF 0 0 0 0 1 0 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data transfer between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 03 - FDC_COMMAND_SPECIFY --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 0 0 0 0 0 1 1 W <---SRT---> <---HUT---> W <-------HLT--------> ND --------------------------- 04 - FDC_COMMAND_SENSE_DRIVE_STATUS --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 0 0 0 0 1 0 0 W 0 0 0 0 0 HDSDS1DS0 Result R ----------ST3---------- Status information about FDD --------------------------- 05 - FDC_COMMAND_WRITE_DATA --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 0 0 1 0 1 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec W ----------------------- Data transfer between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 06 - FDC_COMMAND_READ_DATA --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 0 0 1 1 0 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data transfer between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 07 - FDC_COMMAND_RECALIBRATE --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 0 0 0 0 1 1 1 W 0 0 0 0 0 0DS1DS2 --------------------------- 08 - FDC_COMMAND_SENSE_INTERRUPT_STATUS --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 0 0 0 1 0 0 0 Result R ---------ST0---------- Status information about the FDC at the end of each seek operation R ---------PCN---------- PCN = Present Cylinder No. --------------------------- 09 - FDC_COMMAND_WRITE_DELETED_DATA --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 0 1 0 0 1 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec W ----------------------- Data transfer between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 0A - FDC_COMMAND_READ_ID --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 MF 0 0 1 0 1 0 W 0 0 0 0 0HDSDS1DS2 Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 0B - INVALID --------------------------- 0C - FDC_COMMAND_READ_DELETED_DATA --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 0 1 1 0 0 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data transfer between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 0D - FDC_COMMAND_FORMAT_A_TRACK --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 MF 0 0 1 1 0 0 W 0 0 0 0 0HDSDS1DS2 W ----------N------------ Bytes/Sector W ---------SC------------ Sectors/Track W ---------GPL----------- Gap 3 W ----------D------------ Filler byte Exec ----------------------- FDC Formats an entire track Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- In this case, the sector ID information has no meaning R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 0E - INVALID --------------------------- 0F - FDC_COMMAND_SEEK --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W 0 0 0 0 1 1 1 1 W 0 0 0 0 0HDSDS1DS2 W ----------NCN---------- New Cylinder Number --------------------------- 10 - INVALID --------------------------- 11 - FDC_COMMAND_SCAN_EQUAL --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 1 0 0 0 1 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data compared between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 12 - INVALID 13 - INVALID 14 - INVALID 15 - INVALID 16 - INVALID 17 - INVALID 18 - INVALID --------------------------- 19 - FDC_COMMAND_SCAN_LOW_OR_EQUAL --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 1 0 0 0 1 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data compared between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 1A - INVALID 1B - INVALID 1C - INVALID --------------------------- 1D - FDC_COMMAND_SCAN_HIGH_OR_EQUAL --------------------------- D7 D6 D5 D4 D3 D2 D1 D0 Command W MT MF SK 1 0 0 0 1 W 0 0 0 0 0HDSDS1DS2 W ----------C------------ Sector ID Information W ----------H------------ W ----------R------------ W ----------N------------ W ---------EOT----------- W ---------GPL----------- W ---------DTL----------- Exec R ----------------------- Data compared between the FDD and main system Result R ----------ST0---------- Status information after command execution R ----------ST1---------- R ----------ST2---------- R -----------C----------- Sector ID information after command execution R -----------H----------- R -----------R----------- R -----------N----------- --------------------------- 1E - INVALID 1F - INVALID ; --------------------------- MT Multitrack - If MT is high, a Multitrack operation is performaed. If MT = 1, after finishing Read/Write operation on side 0, FDC will automatically start searching for sector 1 on side 1. MF FM or MFM Mode - If MF is low, FM mode is selected, and if it is high, MFM mode is selected. SK Skip - SK stands for Skip Deleted Data Address mark. ; --------------------------- ; Drive and Head Select Values ; --------------------------- ; HDS - Head Select - Head 1 selected when "1" (high). Head 0 selected when "0" (low). ; DS1DS0 - Drive Select - Selects FDD unit number 00,01,02 or 03 --------------------------- Sector ID Information prior to command execution --------------------------- C Cylinder Number C stands for the current selected Cylinder track number 0 through 76 of the medium H Head Address H stands for head number 0 or 1, as specified in the ID field R Record R stands for the Sector Number which will be read or written. N Number N stands for the number of data bytes written in a sector EOT End Of Track EOT stands for the final Sector number of a Cylinder GPL Gap Length GPL stands for the length of Gap 3 (spacing between sectors excluding VCO Sync field) DTL Data Length When N is defined as 00, DTL stands for the data length which users are going to read out or write into the sector. --------------------------- Example : a) read a sector &c1 at track 0 with MFM Data 46-00 00 00 c1 02 c1 2a ff Note : last parameter DTL can be anything as N=2 b) read a deleted 2 sectors &45 and &46 at track 2 with MFM Data 4c-00 00 00 45 02 46 2a ff Note : last parameter DTL can be anything as N=2 c) scan or equal sector &c1 at track 10 with MFM Data 41-00 00 0a c1 02 c1 2a ff ---------------------------