com20020-5 Standard Microsystems Corp., com20020-5 Datasheet - Page 45

• Manufacturer Part Number: com20020-5
• Description: Com20020-5 Ulanc Universal Local Area Network Controller With 2k X 8 On-board Ram
• Manufacturer: Standard Microsystems Corp.

FIGURE 10A - MULTIPLEXED BUS, 80XX-LIKE CONTROL SIGNALS; READ CYCLE
AD0-AD2,
D3-D7
nCS
ALE
nRD
*
Note 1:
T is the Arbitration Clock Period.
T is identical to XTAL1 if SLOW ARB = 0,
T is twice XTAL1 period if SLOW ARB = 1
t1
t2
t3
t4
t5
t6
t7
t8
The Microcontroller typically accesses the COM20020-5 on every other cycle.
Therefore, the cycle time specified in the microcontroller's datasheet
should be doubled when considering back-to-back COM20020-5 cycles.
Cycle Time (nRD Low to Next Time Low)
nCS Hold from ALE Low
ALE Low to nRD Low
nRD Low to Valid Data
nRD High to Data High Impedance
Address Setup to ALE Low
Address Hold from ALE Low
nCS Setup to ALE Low
t1
t3
VALID
t4
t2,
Parameter
t5
t6
45
VALID DATA
min
4T*
30
10
10
20
15
0
t8
max
40
20
t7
units
nS
nS
nS
nS
nS
nS
nS
nS