Z765A

The Z765A is designed as one kind of LSI floppy disk controller(FDC) chip which contains the circuitry and control functions for interfacing a processor to four floppy disk drives.It supports IBM system 3740 single density format(FM) and IBM system 34 double density format(MFM) including double-sided recording.The Z765A provides control signals which simplify the design of an external phase-locked loop and write precompensation circuitry.The FDC simplifies and handles most of the burdens associated with implementing a floppy disk interface.The Z765A executes 15 commands;each command requires multiple 8-bit bytes to fully specify the operation which the processor wishes the FDC to perform.

Features of the Z765A can be summarized as:(1)address mark detection circuitry internal to the FDC simplifies the phase-locked loop and read electronics. The track stepping rate,head load time,and head unloaded time are user-programmable;(2)IB-compatible format,single and double density;(3)multi-sector and multi-track transfer capability;(4)drives up to four floppy-disk drives(FDD);(5)data transfers in DMA or non-DMA mode;(6)parallel seek operations on up to four drives;(7)compatible with most general purpose microprocessors;(8)single phase 8 MHz clock;(9)multi-sector and multi-track transfer capability.