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NC

E

Description

NEC Electronics Inc.

Features

uPD765A/uPD765B

Single/Double Density

Floppy-Disk Controller

The uPD765A/B is an LSI floppy disk controller (FDC)

chip which contains the circuitry and control functions

for interfacing a processor to 4 floppy disk drives. It is

capableof either

IBM

3740singledensity format (FM), or

IBM System 34 double density format (MFM) including

double-sided recording. The uPD765A/B provides con-

trol signals which simplify the design of an external

phase-locked loop and write precompensation circuitry.

The FDC simplifies and handles most of the burdens as-

sociated with implementing a floppy disk interface.

Hand-shaking signals are provided in the uPD765A/B

which make DMA operation easy to incorporate with the

aid of an external DMA controller chip, such as the

uPD8257. The

FDC will operate in eitherthe DMA or non-

DMA mode. In the non-DMA mode the FDC generates

interrupts to !he processor every time a data byte is to

be transferred. In the DMA mode, the processor need

only load the command into the FDC and all data

transfers occur under control of the FDC and DMA

controllers.

There are 16 commands which the uPD765A/uPD765B

will execute. Most of these commands require multiple

8-bit bytes to fully specify the operation which the

processor wishes the FDC to perform. The following

commands are available.

Read Data

Read ID

Specify

Read Diagnostic

Scan Equal

Scan High or Equal

Scan Low or Equal

Version

Read Deleted Data

Write Data

Write ID (Format Write)

Write Deleted Data

Seek

Recalibrate

Sense Interrupt Status

Sense Drive Status.

Address mark detection circuitry is internal to the FDC

which simplifies the phase-locked loop and read elec-

tronics. The track stepping rate, head load time, and

head unload time are user-programmable. The

uPD765A/uPD765B

offers additional features such as

multi-track and multi-side read and write commands

and single and double density capabilities.

FM, MFM Control

Variable recording length: 128,256, .8192

sector

IBM-compatible format (single- and double-

sided, single- and double-density)

Multi-sector and multi-track transfer capability

Drive up to 4 floppy or micro floppydisk drives

Data scan capability-will scan a single sector or

an entire cylinder comparing byte-for-byte host

memory and disk data

Data transfers in DMA or non-DMA mode

Parallel seek operations on up to four drives

Compatible with uPD8080/85,

uPD8086/88,

and uPD780

(Z80@) microprocessors

Single-phase clock: 8 MHz maximum

3 +5V only

Z80 is a registered trademark of the Zilog

Corporation

V-series

bytes/

Pin Configuration

Ordering Information

Device Number

uPD765AC2

uPD765B

Package

Type

Max

Freq. of Operation

8 MHz

8 MHz

40-pin

plastic DIP

40-pin plastic DIP

NECEL-000324

5-3

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D765相關型號PDF文件下載

• 型號
  版本
  描述
  廠商
  下載
• D765
  英文版
  Single/Double Density Floppy-Disk Controller
  
  D765
• D765
  英文版
  Single/Double Density Floppy-Disk Controller
  NEC [NEC]
  D765

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