
19
IDT70V659/58/57S
High-Speed 3.3V 128/64/32K x 36 Asynchronous Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Functional Description
The IDT70V659/58/57 provides two ports with separate control,
addressandI/Opinsthatpermitindependentaccessforreadsorwrites
toanylocationinmemory.TheIDT70V659/58/57hasanautomaticpower
down feature controlled by CE. The CE0 and CE1 control the on-chip
powerdowncircuitrythatpermitstherespectiveporttogointoastandby
mode when not selected (CE = HIGH). When a port is enabled, access
to the entire memory array is permitted.
Interrupts
Iftheuserchoosestheinterruptfunction,amemorylocation(mail box
or message center) is assigned to each port. The left port interrupt flag
(INTL) is asserted when the right port writes to memory location 1FFFE
(HEX) (FFFE for IDT70V658 and 7FFE for IDT70V657), where a write
isdefinedasCER=R/WR=VILpertheTruthTableIII.Theleftportclears
the interrupt through access of address location 1FFFE (FFFE for
IDT70V658 and 7FFE for IDT70V657) when CEL = OEL = VIL, R/W is
Truth Table IV —
Address BUSY Arbitration
NOTES:
1. Pins BUSYL and BUSYR are both outputs when the part is configured as a master. Both are inputs when configured as a slave. BUSY outputs on the
IDT70V659/58/57 are push-pull, not open drain outputs. On slaves the BUSY input internally inhibits writes.
2. "L" if the inputs to the opposite port were stable prior to the address and enable inputs of this port. "H" if the inputs to the opposite port became stable after the address
and enable inputs of this port. If tAPS is not met, either BUSYL or BUSYR = LOW will result. BUSYL and BUSYR outputs can not be LOW simultaneously.
3. Writes to the left port are internally ignored when BUSYL outputs are driving LOW regardless of actual logic level on the pin. Writes to the right port are internally ignored
when BUSYR outputs are driving LOW regardless of actual logic level on the pin.
4. A16X is a NC for IDT70V658, therefore Address comparison will be for A0 - A15. Also, A16X and A15X are NC's for IDT70V657, therefore Address comparison will
be for A0 - A14.
Inputs
Outputs
Function
CEL
CER
AOL-A16L(4)
AOR-A16R
BUSYL(1)
BUSYR(1)
X
NO MATCH
H
Normal
H
X
MATCHH
HNormal
X
H
MATCHH
HNormal
LL
MATCH
(2)
Write Inhibit(3)
4869 tbl 17
Truth Table V — Example of Semaphore Procurement Sequence(1,2,3)
NOTES:
1. This table denotes a sequence of events for only one of the eight semaphores on the IDT70V659/58/57.
2. There are eight semaphore flags written to via I/O0 and read from all I/O's (I/O0-I/O35). These eight semaphores are addressed by A0 - A2.
3. CE = VIH, SEM = VIL to access the semaphores. Refer to the Semaphore Read/Write Control Truth Table.
Functions
D0 - D35 Left
D0 - D35 Right
Status
No Action
1
Semaphore free
Left Port Writes "0" to Semaphore
0
1
Left port has semaphore token
Right Port Writes "0" to Semaphore
0
1
No change. Right side has no write access to semaphore
Left Port Writes "1" to Semaphore
1
0
Right port obtains semaphore token
Left Port Writes "0" to Semaphore
1
0
No change. Left port has no write access to semaphore
Right Port Writes "1" to Semaphore
0
1
Left port obtains semaphore token
Left Port Writes "1" to Semaphore
1
Semaphore free
Right Port Writes "0" to Semaphore
1
0
Right port has semaphore token
Right Port Writes "1" to Semaphore
1
Semaphore free
Left Port Writes "0" to Semaphore
0
1
Left port has semaphore token
Left Port Writes "1" to Semaphore
1
Semaphore free
4869 tbl 18