5
COMMERCIALTEMPERATURERANGE
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
Symbol
Name
I/O
Description
PIN DESCRIPTIONS (CONTINUED)
MBF1
Mail1 Register Flag
O
MBF1 is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the mail1 register.
Writes to the mail1 register are inhibited while
MBF1 is LOW. MBF1 is set HIGH by a LOW-to-
HIGH transition of CLKB when a Port B read is selected and MBB is HIGH.
MBF1 is set HIGH
following either a Reset (
RS1) or Partial Reset (PRS).
MBF2
Mail2 Register Flag
O
MBF2 is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the mail2 register.
Writes to the mail2 register are inhibited while
MBF2 is LOW. MBF2 is set HIGH by a LOW-to-
HIGH transition of CLKA when a Port A read is selected and MBA is HIGH.
MBF2 is set HIGH
following either a Reset (
RS2) or Partial Reset (PRS).
RS1, RS2
Resets
I
A LOW on both pins initializes the FIFO read and write pointers to the first location of memory and
sets the Port B output register to all zeroes. A LOW-to-HIGH transition on
RS1selectstheprogramming
method (serial or parallel) and one of five programmable flag default offsets. It also configures Port
B for bus size and endian arrangement. Four LOW-to-HIGH transitions of CLKA and four LOW-to-
HIGH transitions of CLKB must occur while
RS1 is LOW.
PRS/
Partial Reset/
I
This pin muxed for both Partial Reset and Retransmit operations, it is used in conjunction with the RTM
RT
Retransmit
pin.IfRTMisLOW,thenaLOWonthispininitializestheFIFOreadandwritepointerstothefirstlocation
of memory and sets the Port B output register to all zeroes. During Partial Reset, the currently
selected bus size, endian arrangement, programming method (serial or parallel), and programmable
flagsettingsareallretained.IfRTMisHIGH,thenaLOWonthispinperformsaRetransmitandinitializes
the read pointer only, to the first memory location.
RTM
RetransmitMode
I
This pin is used in conjunction with the
RT pin. When RTM is HIGH a Retransmit is performed when
RT is taken HIGH.
SIZE(1)
Bus Size Select
I
A HIGH on this pin when BM is HIGH selects byte bus (9-bit) size on Port B. A LOW on this pin
(Port B)
when BM is HIGH selects word (18-bit) bus size. SIZE works with BM and BE to select the bus size
and endian arrangement for Port B. The level of SIZE must be static throughout device operation.
W/
RA
Port A Write/
I
A HIGH selects a write operation and a LOW selects a read operation on Port A for a LOW-to-HIGH
Read Select
transition of CLKA. The A0-A35 outputs are in the HIGH impedance state when W/
RA is HIGH.
W/RB
Port B Write/
I
A LOW selects a write operation and a HIGH selects a read operation on Port B for a LOW-to-HIGH
Read Select
transition of CLKB. The B0-B35 outputs are in the HIGH impedance state when
W/RB is LOW.
NOTE:
1. FS2, BM and SIZE inputs are not TTL compatible. These inputs should be tied to GND or VCC.