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What is UPD765?

This electronic component, produced by the manufacturer "NEC", performs the same function as "SINGLE/DOUBLE DENSITY FLOPPY DISK CONTROLLER".


UPD765 Datasheet PDF - NEC

Part Number UPD765
Description SINGLE/DOUBLE DENSITY FLOPPY DISK CONTROLLER
Manufacturers NEC 
Logo NEC Logo 


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Total 19 Pages



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No Preview Available ! UPD765 datasheet, circuit

NEe Microcomputers, Inc.
NEe
/LPD765
SINGLE/DOUBLE DENSITY
FLOPPY DISK CONTROLLER
DESCRIPTION
FEATURES
PIN CONFIGURATION
TM:Z80 is. registered tredemark of Zilog, Inc,
The J,tPD765 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 capable of supporting either
IBM 3740 single density format (FM), or IBM System 34 Double Density format (MFM) including
double sided recording. The J,tPD765 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.
Hand-shaking signals are provided in the J,tPD765 which make DMA operation easy to incorporate
with the aid of an external DMA Controller chip, such as the J,tPD8257. The FDC will operate in
either DMA or Non·DMA mode. In the Non·DMA mode, the FDC generates interrupts to the
processor every time a data byte is available. In the DMA mode, the processor need only load the
command into the FDC and all data transfers occur under control of theJ,tPD765 and DMA
controller.
There are 15 separate commands which the J,tPD765 will execute. Each of these commands requ ire
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
Read Deleted Data
Read a Track
Scan Equal
Scan High or Equal
Scan Low or Equal
Specify
Write Data
Format a Track
Write Deleted Data
Seek
Recalibrate (Restore to Track 0)
Sense Int"rrupt Status
Sense Drive Status
Address mark detection circuitry is internal to the FDC which simplifies the phase locked loop ana
read electronics. The track stepping rate, head load time, and head unload time may be programmed
by the user. The J,tPD765 offers many additional features such as multiple .ector transfers in both
read and write with a single command, and full IBM compatibility in both single and double
density modes.
o IBM Compatible in Both Single and Double Density Recording Formats
o Programmable Data Record Lengths: 128,256,512, or 1024 Bytes/Sector
o Multi·Sector and Multi-Track Transfer Capability
o Drive Up to 4 Floppy Disks
o Data Scan Capability - Will Scan a Single Sector or an Entire Cylinder's Worth of Data Fields,
Comparing on a Byte by Byte Basis, Data in the Processor's Memory with Data Read from the
Diskette
• Data Transfers in DMA or Non-DMA Mode
o Parallel Seek Operations on Up to Four Drives
o Compatible with Most Microprocessors Including 8080A, 8085A, J,tPD780 (Z80TM)
o Single Phase 8 MHz Clock
o Single +5 Volt Power Supply
o Available in 40 Pin Plastic Dual-in-Line Package
RESET 1
40 vcc
RD 2
FiW/SEEK
WR LCT/DIR
Cs 4
AO 5
FR/STP
HDL
DBO 6
ROY
OB, 7
WP/TS
DB2
DB3
8
9
/oIPD
FLT/TR(
'PSo
DB4 10 765
DB5 11
DB6 12
DB7 13
14
15
16
17 VCO
18 RO
19 ROW
= ______-'WCK
Rev/2
423

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UPD765 equivalent
TIMING WAVEFORMS
PROCESSOR READ OPERATION
: J (AO. Cs. i5AcK
~'"___
TAR__ 1_
--' I--TRA
RD~TRR_t
L..----I
DATA ------I -10TRD}:
I
- l t--TDF
!)I ------
INT _ _ _ _ _ _ _ _ _ _~_T_R"I-"-"-".\-lI
\...
PROCESSOR WRITE OPERATION
pPD765
ClK
DRaJ:
;-
DMA OPERATION
r -\.~_---,r
TAM--J 14-
1
\ TMCY
WR OR RD
I' TMR~-J.:
t-- --ll--TMW IWR)--l~
TMR lAD)
FDD WRITE OPERATION
WRITE CLOCK I
II I
1
11-1 I--TF ~TCy---I
TR~:~~_ _ _~I~I_ _ _ _ _ _ _ _ _~
~WRITE ENABLE
:I
'-
x::_ I It-I-Tcp
PRESHIFTO OR ~~,.....--..t,T¥"I':=1:-~--"'X...- - - -
WRITE DATA
_ I I..oi-TCD --I
II
NORMAL
LATE
EARLY
INVALID
PRESHIFT a
a
a
1
1
PRESHIFT 1
a
1
a
1
II
427


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Part Details

On this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for UPD765 electronic component.


Information Total 19 Pages
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Featured Datasheets

Part NumberDescriptionMFRS
UPD765The function is SINGLE/DOUBLE DENSITY FLOPPY DISK CONTROLLER. NECNEC
UPD765AThe function is Single / Double Density Floppy-Disk Controller. NEC ElectronicsNEC Electronics
UPD765BThe function is Single / Double Density Floppy-Disk Controller. NEC ElectronicsNEC Electronics

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