DP8522AV-25 National Semiconductor, DP8522AV-25 Datasheet - Page 46

• Manufacturer Part Number: DP8522AV-25
• Description: IC CTRLR 4M VRAM 25MHZ 68PLCC
• Manufacturer: National Semiconductor

Specifications of DP8522AV-25

• Controller Type: Video RAM Controller, Drivers
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 68-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Voltage - Supply: -
• Interface: -
• Other names: *DP8522AV-25

12 0 Dual Accessing Functions (DP8522A)
Since the DP8522A has only one set of address inputs the
signal is used with the addition of buffers to allow the cur-
rently granted port’s addresses to reach the DP8522A The
signals which need to be bufferred are R0–10 C0–10
B0 –1 ECAS0 –1 and LOCK All other inputs are not com-
mon and do not have to be buffered as shown in Figure 58a
If a Port which is not currently granted tries to access
If Port B is synchronous the Request Synchronizing logic will not be required
FIGURE 58a Dual Accessing Using the DP8522A to interface a CPU and a Graphics Processor to a Video RAM System
Dual Accessing Using the DP8522A
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the VRAM array the GRANTB output will transition from a
rising clock edge from AREQ or AREQB negating and will
preceed the RAS for the access by one or two clock peri-
ods GRANTB will then stay in this state until the other port
requests an access and the currently granted port is not
accessing the VRAM as shown in Figure 58b
(Continued)
TL F 9338– 1