4

256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2

COMMERCIAL TEMPERATURERANGE

Symbol

Name

I/O

Description

A0-A35

Port A Data

I/0

36-bitbidirectionaldataportforsideA.

AEA

PortAAlmost-

O

Programmable Almost-Empty flag synchronized to CLKA. It is LOW when the number of words in FIFO2 is

EmptyFlag

(Port A) less than or equal to the value in the Almost-Empty A Offset register, X2.

AEB

PortBAlmost-

O

ProgrammableAlmost-EmptyflagsynchronizedtoCLKB.ItisLOWwhenthenumberof words in FIFO1 is

EmptyFlag

(Port B) less than or equal to the value in the Almost-Empty B Offset register, X1.

AFA

PortAAlmost-

O

ProgrammableAlmost-FullflagsynchronizedtoCLKA.ItisLOWwhenthenumberofempty locationsin

Full Flag

(Port A) FIFO1 is less than or equal to the value in the Almost-Full A Offset register, Y1.

AFB

PortBAlmost-

O

ProgrammableAlmost-FullflagsynchronizedtoCLKB.ItisLOWwhenthenumberofempty locationsin

Full Flag

(Port B) FIFO2 is less than or equal to the value in the Almost-Full B Offset register, Y2.

B0 - B35

Port B Data

I/O

36-bitbidirectionaldataportforsideB.

CLKA

Port A Clock

I

CLKA is a continuous clock that synchronizes all data transfers through port A and can be asynchronous or

coincident to CLKB. FFA/IRA, EFA/ORA, AFA, and AEA are all synchronized to the LOW-to-HIGH

transitionofCLKA.

CLKB

Port B Clock

I

CLKB is a continuous clock that synchronizes all data transfers through port Band can be asynchronous or

coincident to CLKA. FFB/IRB, EFB/ORB, AFB, and AEB are synchronized to the LOW-to-HIGH

transitionofCLKB.

CSA

Port A Chip

I

CSA must be LOW to enable a LOW-to-HIGH transition of CLKA to read or write on port A. The A0-A35

Select

outputs are in the high-impedance state when CSA is HIGH.

CSB

Port B Chip

I

CSB must be LOW to enable a LOW-to-HIGH transition of CLKB to read or write data on port B. The

Select

B0- B35 outputs are in the high-impedance state when CSB is HIGH.

EFA/ORA

PortAEmpty/

O

This is a dual function pin. In the IDT Standard mode, the EFA function is selected. EFA indicates

OutputReady

whether or not the FIFO2 memory is empty. In the FWFT mode, the ORA function is selected. ORA

Flag

indicates the presence of valid data on A0-A35 outputs, available for reading. EFA/ORA is synchronized

totheLOW-to-HIGHtransitionofCLKA.

EFB/ORB

PortBEmpty/

O

This is a dual function pin. In the IDT Standard mode, the EFB function is selected. EFB indicates

OutputReady

whether or not the FIFO1 memory is empty. In the FWFT mode, the ORB function is selected. ORB

Flag

indicates the presence of valid data on B0-B35 outputs, available for reading. EFB/ORB is synchronized to

theLOW-to-HIGHtransitionofCLKB.

ENA

Port A Enable

I

ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on port A.

ENB

Port B Enable

I

ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or write data on port B.

FFA/IRA

Port A Full/

O

This is a dual function pin. In the IDT Standard mode, the FFA function is selected. FFA indicates whether

Input Ready

or not the FIFO1 memory is full. In the FWFT mode, the IRA function is selected. IRA indicates whether or

Flag

not there is space available for writing to the FIFO1 memory. FFA/IRA is synchronized to the LOW-to-

HIGHtransitionofCLKA.

FFB/IRB

Port B Full/

O

This is a dual function pin. In the IDT Standard mode, the FFB function is selected. FFB indicates whether

Input Ready

or not the FIFO2 memory is full. In the FWFT mode, the IRB function is selected. IRB indicates whether or

Flag

not there is space available for writing to the FIFO2 memory. FFB/IRB is synchronized to the LOW-to-

HIGHtransitionofCLKB.

FWFT

FirstWordFall

I

This pin selects the timing mode. A HIGH on FWFT selects IDT Standard mode, a LOW selects First

Through Mode

Word Fall Through mode. Once the timing mode has been selected, the level on FWFT must be static

throughoutdeviceoperation.

FS1, FS0

FlagOffset

I

A LOW-to-HIGH transition of the FIFO Reset input latches the values of FS0 and FS1. If either FS0 or

Selects

FS1 is HIGH when the FIFO Reset input goes HIGH, one of three preset values is selected as the

offset for FIFOs Almost-Full and Almost-Empty flags. If both FIFOs are reset simultaneously and both

FS0 and FS1 are LOW when RST1 and RST2 go HIGH, the first four writes to FIFO1 load the Almost-

Empty and Almost-Full offsets for both FIFOs.

PIN DESCRIPTIONS