參數(shù)資料
型號: HM-6551
廠商: Intersil Corporation
英文描述: 256 x 4 CMOS RAM
中文描述: 256 × 4 CMOS存儲器
文件頁數(shù): 7/9頁
文件大小: 116K
代理商: HM-6551
6-107
Timing Waveforms
(Continued)
In the Write Cycle the falling edge of E latches the addresses
and S2 into on-chip registers. S2 must be latched in the low
state to enable the device. The write portion of the cycle is
defined as E, W, S1 being low and S2 being latched simulta-
neously. The W line may go low at any time during the cycle
providing that the write pulse setup times (TWLEH and
TWLS1H) are met. The write portion of the cycle is terminated
on the first rising edge of either E, W, or S1.
If a series of consecutive write cycles are to be executed, the
W line may be held low until all desired locations have been
written. If this method is used, data setup and hold times must
be referenced to the first rising edge of E or S1. By positioning
the write pulse at different times within the E and S1 low time
(TELEH), various types of write cycles may be performed. If
the S1 low time (TS1LS1H) is greater than the W pulse, plus
an output enable time (TS1LQX), a combination read-write
cycle is executed. Data may be modified an indefinite number
of times during any write cycle (TELEH).
The HM-6551/883 may be used on a common I/O bus struc-
ture by tying the input and output pins together. The multiplex-
ing is accomplished internally by the W line. In the write cycle,
when W goes low, the output buffers are forced to a high
impedance state. One output disable time delay (TWLQZ)
must be allowed before applying input data to the bus.
(8) TAVEL
VALID
(8) TAVEL
NEXT
TELEH (6)
(11)
TWHDX (13)
TELEL (19)
(9) TS2LEL
TEHEL (7)
TELS2X
(9) TS2LEL
TWLEH (15)
TDVWH (12)
TWLWH (18)
TS1LWH (16)
TWLS1H (14)
-1
TIME
0
1
2
3
4
5
REFERENCE
A
E
S2
D
W
S1
(10)
TELAX
TEHEL (7)
DATA VALID
TELWH (17)
FIGURE 2. WRITE CYCLE
TRUTH TABLE
TIME
REFERENCE
INPUTS
OUTPUTS
FUNCTION
E
S1
S2
W
A
D
Q
-1
H
H
X
X
X
X
Z
Memory Disabled
0
X
L
X
V
X
Z
Cycle Begins, Addresses and S2 are
Latched
1
L
L
X
X
X
Z
Write Period Begins
2
L
L
X
X
V
Z
Data In is Written
3
X
X
H
X
X
Z
Write is Completed
4
H
H
X
X
X
X
Z
Prepare for Next Cycle (Same as -1)
5
X
L
X
V
X
Z
Cycle Ends, Next Cycle Begins
(Same as 0)
HM-6551/883
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
HM-6551/883 制造商:未知廠家 制造商全稱:未知廠家 功能描述:256 x 4 CMOS RAM
HM-6551_03 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:256 x 4 CMOS RAM
HM-6551883 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:256 x 4 CMOS RAM
HM-6551B883 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:256 x 4 CMOS RAM
HM-6561 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:256 x 4 CMOS RAM