8086 Notes
Microprocessors and Microcontrollers/Interfacing with 8086
Lecture Notes
Module 3 Learning unit 8: Interface
• • • • • • • • • We have four common types of memory: Read only memory (ROM) Flash memory (EEPROM) Static Random access memory (SARAM) Dynamic Random access memory (DRAM). Pin connections common to all memory devices are: The address input, data output or input/outputs, selection input and control input used to select a read or write operation. Address connections: All memory devices have address inputs that select a memory location within the memory device. Address inputs are labeled from A0 to An. Data connections: All memory devices have a set of data outputs or input/outputs. Today many of them have bi-directional common I/O pins. Selection connections: Each memory device has an input, that selects or enables the memory device. This kind of input is most often called a chip select ( CS ), chip enable ( CE ) or simply select ( S ) input.
A0
ADDRESS CONNECTION
O0 O1 O2
OUTPUT OR INPUT/OUTPUT CONNECTION
A1 A2
AN
ON
CS
WE OE
WRITE
SELECT
READ
MEMORY COMPONENT ILLUSTRATING THE ADDRESS, DATA AND , CONTROL CONNECTIONS
• • RAM memory generally has at least one CS or S input and ROM at least one CE . If the CE , CS , S input is active the memory device perform the read or write.
M. Krishna Kumar/IISc. Bangalore
M3/V1/June 04/1
Microprocessors and Microcontrollers/Interfacing with 8086
Lecture Notes
• • • • • • • • • • • • • • • • • • • • • • •
If it is inactive the memory device cannot perform read or write operation. If more than one CS connection is present, all most be active to perform read or write data. Control connections: A ROM usually has only one control input, while a RAM often has one or two control inputs. The control input most often found on the ROM is the output enable ( OE ) or gate ( G ), this allows data to flow out of the output data pins of the ROM. If OE and the selected input
Lecture Notes
Module 3 Learning unit 8: Interface
• • • • • • • • • We have four common types of memory: Read only memory (ROM) Flash memory (EEPROM) Static Random access memory (SARAM) Dynamic Random access memory (DRAM). Pin connections common to all memory devices are: The address input, data output or input/outputs, selection input and control input used to select a read or write operation. Address connections: All memory devices have address inputs that select a memory location within the memory device. Address inputs are labeled from A0 to An. Data connections: All memory devices have a set of data outputs or input/outputs. Today many of them have bi-directional common I/O pins. Selection connections: Each memory device has an input, that selects or enables the memory device. This kind of input is most often called a chip select ( CS ), chip enable ( CE ) or simply select ( S ) input.
A0
ADDRESS CONNECTION
O0 O1 O2
OUTPUT OR INPUT/OUTPUT CONNECTION
A1 A2
AN
ON
CS
WE OE
WRITE
SELECT
READ
MEMORY COMPONENT ILLUSTRATING THE ADDRESS, DATA AND , CONTROL CONNECTIONS
• • RAM memory generally has at least one CS or S input and ROM at least one CE . If the CE , CS , S input is active the memory device perform the read or write.
M. Krishna Kumar/IISc. Bangalore
M3/V1/June 04/1
Microprocessors and Microcontrollers/Interfacing with 8086
Lecture Notes
• • • • • • • • • • • • • • • • • • • • • • •
If it is inactive the memory device cannot perform read or write operation. If more than one CS connection is present, all most be active to perform read or write data. Control connections: A ROM usually has only one control input, while a RAM often has one or two control inputs. The control input most often found on the ROM is the output enable ( OE ) or gate ( G ), this allows data to flow out of the output data pins of the ROM. If OE and the selected input