Interface design compute memory timing
Sponsored Links
This presentation is the property of its rightful owner.
1 / 54

Interface Design Compute Memory Timing PowerPoint PPT Presentation


  • 62 Views
  • Uploaded on
  • Presentation posted in: General

Interface Design Compute Memory Timing. Omid Fatemi ([email protected]). Outline. Connecting to micro-processor Timing of microprocessor Timing of memory Interfacing memory. Compute. Convey. Cooperate. Typical Interface Design. Connect. Sense Reality Touch Reality Connect Transform.

Download Presentation

Interface Design Compute Memory Timing

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Interface DesignComputeMemory Timing

Omid Fatemi

([email protected])


Outline

  • Connecting to micro-processor

  • Timing of microprocessor

  • Timing of memory

  • Interfacing memory


Compute

Convey

Cooperate

Typical Interface Design

Connect

Sense Reality

Touch Reality

Connect

Transform

Embedded Systems

Micros

Assembler, C

Real-Time

Memory

Peripherals

Timers

DMA

Busses

Protocols

Standards

PCI

IEEE488

SCSI

USB & FireWire

CAN

PC interfaces

HCI


Processor Timing Diagramfor any memory read machine cycle


Processor Timing Diagramfor any memory write machine cycle


When interfacing memory chips to a microprocessor, consider the following:

  • TAVDV – address access time

  • TRLDV – read access time

  • TDVWH – memory setup time

  • TWHDX – data hold time

  • TWLWH – write pulse width

    Refer to 8088 data manual


Address Access Time (TAVDV)


Timing Requirements during Memory Read

  • TAVDV

    • 3TCLCL – TCLAV – TDVCL

    • Address Access Time

    • from Address is Valid to Data is Valid


Read Access Time (TRLDV)


Timing Requirements during Memory Read

  • TRLDV

    • 2TCLCL – TCLRL – TDVCL

    • Read Access Time

    • from Read Signal is Low to Data is Valid


Memory Setup Time (TDVWH)


Timing Requirements during Memory Write

  • TDVWH

    • 2TCLCL – TCLDV +TCVCTX

    • Memory Setup Time

    • from Data is Valid to Write Signal is High


Data Hold Time (TWHDX)


Timing Requirements during Memory Write

  • TWHDX

    • TCLCH – X

    • Data Hold Time (after WR’)

    • from Write Signal is High to Data is Invalid (Inactive)


Write Pulse Width / Write-Time (TWLWH)


Timing Requirements during Memory Write

  • TWLWH

    • 2TCLCL – Y

    • Write Pulse Width / Write-Time

    • from Write Signal is Low to Write Signal is High


8088 MINIMUM COMPLEXITY SYSTEM TIMING REQUIREMENTS


Computation of Timing Requirements for 8088 using a 4Mhz Clock

  • TAVDV

    • 3TCLCL – TCLAVmax – TDVCLmin

    • 3(250 ns) – 110 ns – 30 ns

    • 610 ns

  • TRLDV

    • 2TCLCL – TCLRLmax – TDVCLmin

    • 3(250 ns) – 165 ns – 30 ns

    • 555 ns


8088 MINIMUM COMPLEXITY SYSTEM TIMING REQUIREMENTS


Computation of Timing Requirements for 8088 using a 4Mhz Clock

  • TDVWH

    • 2TCLCL – TCLDVmax +TCVCTXmin

    • 2(250 ns) – 110 ns + 10 ns

    • 400 ns

  • TWHDX

    • TCLCH – X

    • 118 ns – 30 ns

    • 88 ns

  • TWLWH

    • 2TCLCL – Y

    • 2(250 ns) – 60 ns

    • 440 ns


Timing Requirements for 8088 using a 4Mhz Clock

  • TAVDV = 610 ns

  • TRLDV = 555 ns

  • TDVWH = 400 ns

  • TWHDX = 88 ns

  • TWLWH = 440 ns


Can we interface a 6264 to the 8088 chip which uses a 4MHz clock?


Timing Requirements for 6264 SRAM

  • TAVDV = ?

  • TRLDV = ?

  • TDVWH = ?

  • TWHDX = ?

  • TWLWH = ?


HM6264B

-

8L

HM6264B

-

10L

Symbol

Parameter

Units

Min

Max

Min

Max

t

Read cycle time

85

100

ns

RC

t

Address access time

85

100

ns

AA

t

Chip select access time (CS1’)

85

100

ns

CO1

t

Chip select access time (CS2’)

85

100

ns

CO2

t

Output enable to output valid

45

50

ns

OE

Chip selection to output in low

-

Z

t

10

10

ns

LZ1

(CS1)

Chip selection to output in low

-

Z

t

10

10

ns

LZ2

(CS2)

t

Output enable to output in low

-

Z

5

5

ns

OLZ

Chip deselection in to output i

n

t

0

30

0

35

ns

HZ1

high

-

Z (CS1’)

t

HM6264B Series Read TIMING REQUIREMENTS

Chip deselection in to output in

0

30

0

35

ns

HZ2

high

-

Z (CS2’)

t

Output disable to output in high

-

Z

0

30

0

35

ns

OHZ

t

Output hold from address change

10

10

ns

OH


HM6264B Series Write TIMING REQUIREMENTS


HM6264B Series Read Timing Diagram


HM6264B Series Write Timing Diagram


Timing Requirements for 6264 SRAM

  • TAVDV = tAA

  • TRLDV = tOE

  • TDVWH = tDW

  • TWHDX = tDH

  • TWLWH = tWP


Timing Requirements for HM6264B-8L

  • TAVDV = tAA = ?

  • TRLDV = tOE = ?

  • TDVWH = tDW = ?

  • TWHDX = tDH = ?

  • TWLWH = tWP = ?


HM6264B Series Read TIMING REQUIREMENTS


HM6264B Series Write TIMING REQUIREMENTS


Timing Requirements for HM6264B-8L

  • TAVDV = tAA = 85 ns

  • TRLDV = tOE = 45 ns

  • TDVWH = tDW = 40 ns

  • TWHDX = tDH = 0 ns

  • TWLWH = tWP = 55 ns


Comparing Timing Requirements of 8088 (using 4 Mhz clock) and HM6264B-8L


Can we interface a 2764 to the 8088 chip which uses a 4MHz clock?


Timing Requirements for 2764 EPROM

  • TAVDV = ?

  • TRLDV = ?

  • TDVWH = ?

  • TWHDX = ?

  • TWLWH = ?


M2764A Read Mode AC Characteristics


M2764A Read Mode Timing Diagram


Timing Requirements for 2764 EPROM

  • TAVDV = tAVQV

  • TRLDV = tGLQV

  • TDVWH = N/A

  • TWHDX = N/A

  • TWLWH = N/A


Timing Requirements for 2764 EPROM

  • TAVDV = tAVQV = ?

  • TRLDV = tGLQV = ?

  • TDVWH = N/A

  • TWHDX = N/A

  • TWLWH = N/A


M2764A Read Mode AC Characteristics


Timing Requirements for M2764A-3

  • TAVDV = tAVQV = 180 ns

  • TRLDV = tGLQV = 65 ns

  • TDVWH = N/A

  • TWHDX = N/A

  • TWLWH = N/A


Comparing Timing Requirements of 8088 (using 4 Mhz clock) and M2764A-3


What if we need to interface a “slow” memory to the 8088?


Comparing Timing Requirements of 8088 (using 4 Mhz clock) and a certain “slow” memory chip


Recall:Write Pulse Width / Write-Time (TWLWH)


Write Pulse Width / Write-Time (TWLWH) w/ 1 wait state


Comparing Timing Requirements of 8088 (using 4 Mhz clock) and a certain memory chip

caused by 1 wait state during a memory write on the “slow” memory chip


How do we produce a wait state?

  • By turning the READY input of the 8088 microprocessor to LOW


Requirements for the READY input of the 8088


Requirements for the RDY of the 8284


  • Login