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Intersil Electronic Components Datasheet

ID82C237 Datasheet

CMOS High Performance Programmable DMA Controller

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ID82C237 pdf
82C237
March 1997
CMOS High Performance
Programmable DMA Controller
Features
Description
• Fully Compatible with Intersil 82C37A
- 82C237 May be Used in 8MHz and 12.5MHz 82C37A
Sockets
• Optimized for 10MHz and 12.5MHz 80C286 Systems
• Special Mode Permits 16-Bit, Zero Wait State DMA
Transfers
• High Speed Data Transfers:
- Up to 6.25MBytes/sec with 12.5MHz Clock in
Normal Mode
- Up to 12.5MBytes/sec with 12.5MHz Clock in 16-Bit
Mode
• Compatible with the NMOS 8237A
• Four Independent Maskable Channels with Autoinitial-
ization Capability
• Cascadable to any Number of Channels
• Memory-to-Memory Transfers
• Static CMOS Design Permits Low Power Operation
- ICCSB = 10µA Maximum
- ICCOP = 2mA/MHz Maximum
• Fully TTL/CMOS Compatible
• Internal Registers may be Read from Software
The 82C237 is a modified version of the 82C37A. The
82C237 is fully software and pin for pin compatible with the
82C37A but provides an additional mode for 16-bit DMA
transfers, as well as enhanced speed. Each channel may be
individually programmed for 8-bit or 16-bit data transfers.
The 82C237 controller can improve system performance by
allowing external devices to transfer data directly to or from
system memory. Memory-to-memory transfer capability is
also provided, along with a memory block initialization fea-
ture. DMA requests may be generated by either hardware or
software, and each channel is independently programmable
with a variety of features for flexible operation.
The 82C237 is designed to be used with an external address
latch, such as the 82C82, to demultiplex the most significant
8 bits of address. An additional latch is required to
temporarily store the most significant 8 bits of data if 16-bit
memory-to-memory transfers are desired. The 82C237 can
be used with industry standard microprocessors such as
80C286, 80286, 80C86, 80C88, 8086, 8088, 8085, Z80,
NSC800, 80186 and others. Multimode programmability
allows the user to select from three basic types of DMA
services, and reconfiguration under program control is
possible even with the clock to the controller stopped. Each
channel has a full 64K address and word count range, and
may be programmed to autoinitialize these registers
following DMA termination (end of process).
Ordering Information
PACKAGE
PDIP
PLCC
SBDIP
TEMPERATURE
RANGE
0oC to +70oC
-40oC to +85oC
0oC to +70oC
-40oC to +85oC
0oC to +70oC
-40oC to +85oC
-55oC to +125oC
SMD#
CLCC
SMD#
-55oC to +125oC
8MHz
CP82C237
IP82C237
CS82C237
IS82C237
CD82C237
ID82C237
MD82C237/B
5962-9054304MQA
MR82C237/B
5962-9054304MXA
12.5MHz
CP82C237-12
IP82C237-12
CS82C237-12
IS82C237-12
CD82C237-12
ID82C237-12
MD82C237-12/B
5962-9054305MQA
MR82C237-12/B
5962-9054305MXA
PKG. NO.
E40.6
E40.6
N44.65
N44.65
F40.6
F40.6
F40.6
F40.6
J44.A
J44.A
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
http://www.intersil.com or 407-727-9207 | Copyright © Intersil Corporation 1999
4-148
File Number 2965.1



Intersil Electronic Components Datasheet

ID82C237 Datasheet

CMOS High Performance Programmable DMA Controller

No Preview Available !

ID82C237 pdf
82C237
Pinouts
82C237 (DIP)
TOP VIEW
IOR 1
IOW 2
MEMR 3
MEMW
DWLE
(NOTE)
READY
HLDA
4
5
6
7
ADSTB 8
AEN 9
HRQ 10
CS 11
CLK 12
RESET 13
DACK2 14
DACK3 15
DREQ3 16
DREQ2 17
DREQ1 18
DREQ0 19
(GND) VSS 20
40 A7
39 A6
38 A5
37 A4
36 EOP
35 A3
34 A2
33 A1
32 A0
31 VCC
30 DB0
29 DB1
28 DB2
27 DB3
26 DB4
25 DACK0
24 DACK1
23 DB5
22 DB6
21 DB7
82C237 (CLCC/PLCC)
TOP VIEW
6 5 4 3 2 1 44 43 42 41 40
NC 7
39 A3
NC 8
38 A2
HLDA 9
37 A1
ADSTB 10
36 A0
AEN 11
HRQ 12
35 VCC
34 DB0
CS 13
33 DB1
CLK 14
32 DB2
RESET 15
31 DB3
DACK2 16
NC 17
30 DB4
29 NC
18 19 20 21 22 23 24 25 26 27 28
NOTE: See Pin Description.
Block Diagram
DWLE
EOP
RESET
CS
READY
CLK
AEN
ADSTB
MEMR
MEMW
IOR
IOW
TIMING
AND
CONTROL
DREQ0 -
DREQ3
HLDA
HRQ
DACK0 -
DACK3
4
4
PRIORITY
ENCODER
AND
ROTATING
PRIORITY
LOGIC
DECREMENTOR
TEMP WORD
COUNT REG (16)
INC DECREMENTOR
TEMP ADDRESS
REG (16)
16-BIT BUS
16-BIT BUS
READ BUFFER
READ WRITE BUFFER
BASE
ADDRESS
(16)
BASE
WORD
COUNT
(16)
CURRENT
ADDRESS
(16)
CURRENT
WORD
COUNT
(16)
IO
BUFFER
A0 - A3
OUTPUT
BUFFER
A4 - A7
COMMAND
CONTROL
DATA-WIDTH
(4)
COMMAND
(8)
MASK
(4)
REQUEST
(4)
WRITE
BUFFER
READ
BUFFER
INTERNAL DATA BUS
D0 - D1
IO
BUFFER
MODE
(4 x 6)
STATUS
(8)
TEMPORARY
(8)
4-149



Intersil Electronic Components Datasheet

ID82C237 Datasheet

CMOS High Performance Programmable DMA Controller

No Preview Available !

ID82C237 pdf
82C237
Pin Description
PIN
SYMBOL NUMBER TYPE
DESCRIPTION
VCC
31
VCC: is the +5V power supply pin. A 0.1µF capacitor between pins 31 and 20 is recommended for
decoupling.
GND
20
Ground
CLK 12 I CLOCK INPUT: The Clock Input is used to generate the timing signals which control 82C237
operations. This input may be driven from DC to 12.5MHz for the 82C237-12 or from DC to 8MHz
for the 82C237. The Clock may be stopped in either state for standby operation.
CS
RESET
11
13
READY
6
HLDA
7
DREQ0-
DREQ3
16-19
I CHIP SELECT: Chip Select is an active low input used to enable the controller onto the data bus for
CPU communications.
I RESET: This is an active high input which clears the Command, Status, Request, and Temporary
registers, the First/Last Flip-Flop, and the mode register counter. The Mask register is set to ignore
requests. The Data-Width register is set to perform 8-bit transfers on all channels (82C237 only).
Following a Reset, the controller is in an idle cycle.
I READY: This signal can be used to extend the memory read and write pulses from the 82C237 to
accommodate slow memories or I/O devices. READY must not make transitions during its specified
set-up and hold times. See Figure 14 for timing. READY is ignored in verify transfer mode.
I HOLD ACKNOWLEDGE: The active high Hold Acknowledge from the CPU indicates that it has
relinquished control of the system busses. HLDA is a synchronous input and must not transition
during its specified set-up time. There is an implied hold time (HLDA inactive) of TCH from the rising
edge of clock, during which time HLDA must not transition.
I DMA REQUEST: The DMA Request (DREQ) lines are individual asynchronous channel request
inputs used by peripheral circuits to obtain DMA service. In Fixed Priority, DREQ0 has the highest
priority and DREQ3 has the lowest priority. A request is generated by activating the DREQ line of a
channel. DACK will acknowledge the recognition of a DREQ signal. Polarity of DREQ is
programmable. RESET initializes these lines to active high. DREQ must be maintained until the
corresponding DACK goes active. DREQ will not be recognized while the clock is stopped. Unused
DREQ inputs should be pulled High or Low (inactive) and the corresponding mask bit set. In 16-bit
Transfer mode (82C237 only), each DREQ channel may be programmed to perform either 8-bit or
16-bit DMA transfers.
DB0-DB7
21-23
26-30
I/O DATA BUS: The Data Bus lines are bidirectional three-state signals connected to the system data
bus. The outputs are enabled in the Program condition during the I/O Read to output the contents
of a register to the CPU. The outputs are disabled and the inputs are read during an I/O Write cycle
when the CPU is programming the 82C237 control registers. During DMA cycles, the most signifi-
cant 8-bits of the address are output onto the data bus to be strobed into an external latch by ADSTB.
In memory-to-memory operations, data from the memory enters the 82C237 on the data bus during
the read-from-memory transfer, then during the write-to-memory transfer, the data bus outputs write
the data into the new memory location.
IOR 1 I/O I/O READ: I/O Read is a bidirectional active low three-state line. In the Idle cycle, it is an input con-
trol signal used by the CPU to read the control registers. In the Active cycle, it is an output control
signal used by the 82C237 to access data from the peripheral during a DMA Write transfer.
IOW 2 I/O I/O WRITE: I/O Write is a bidirectional active low three-state line. In the Idle cycle, it is an input con-
trol signal used by the CPU to load information into the 82C237. In the Active cycle, it is an output
control signal used by the 82C237 to load data to the peripheral during a DMA Read transfer.
4-150




Part Number ID82C237
Description CMOS High Performance Programmable DMA Controller
Maker Intersil Corporation
Total Page 25 Pages
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