dp8421a National Semiconductor Corporation, dp8421a Datasheet - Page 2

• Manufacturer Part Number: dp8421a
• Description: Microcmos Programmable 256k/1m/4m Dynamic Ram Controller/drivers
• Manufacturer: National Semiconductor Corporation

1 0 INTRODUCTION
2 0 SIGNAL DESCRIPTIONS
3 0 PROGRAMMING AND RESETTING
4 0 PORT A ACCESS MODES
5 0 REFRESH OPTIONS
2 1 Address R W and Programming Signals
2 2 DRAM Control Signals
2 3 Refresh Signals
2 4 Port A Access Signals
2 5 Port B Access Signals (DP8422A)
2 6 Common Dual Port Signals (DP8422A)
2 7 Power Signals and Capacitor Input
2 8 Clock Inputs
3 1 External Reset
3 2 Programming Methods
3 3 Internal Programming Modes
4 1 Access Mode 0
4 2 Access Mode 1
4 3 Extending CAS with Either Access Mode
4 4 Read-Modify-Write Cycles with Either Access Mode
4 5 Additional Access Support Features
5 1 Refresh Control Modes
5 2 Refresh Cycle Types
5 3 Extending Refresh
5 4 Clearing the Refresh Address Counter
5 5 Clearing the Refresh Request Clock
4 5 1 Address Latches and Column Increment
4 5 2 Address Pipelining
4 5 3 Delay CAS During Write Accesses
5 1 1 Automatic Internal Refresh
5 1 2 Externally Controlled Burst Refresh
5 1 3 Refresh Request Acknowledge
5 2 1 Conventional Refresh
5 2 2 Staggered Refresh
5 2 3 Error Scrubbing Refresh
3 2 1 Mode Load Only Programming
3 2 2 Chip Selected Access Programming
TM
Table of Contents
2
6 0 PORT A WAIT STATE SUPPORT
7 0 RAS AND CAS CONFIGURATION MODES
8 0 TEST MODE
9 0 DRAM CRITICAL TIMING PARAMETERS
10 0 DUAL ACCESSING (DP8422A)
11 0 ABSOLUTE MAXIMUM RATINGS
12 0 DC ELECTRICAL CHARACTERISTICS
13 0 AC TIMING PARAMETERS
14 0 FUNCTIONAL DIFFERENCES BETWEEN THE
15 0 DP8420A 21A 22A USER HINTS
6 1 WAIT Type Output
6 2 DTACK Type Output
6 3 Dynamically Increasing the Number of Wait States
6 4 Guaranteeing RAS Low Time and RAS Precharge
7 1 Byte Writing
7 2 Memory Interleaving
7 3 Address Pipelining
7 4 Error Scrubbing
7 5 Page Burst Mode
9 1 Programmable Values of t
9 2 Calculation of t
10 1 Port B Access Mode
10 2 Port B Wait State Support
10 3 Common Port A and Port B Dual Port Functions
DP8420A 21A 22A AND THE DP8420 21 22
Time
10 3 1 GRANTB Output
10 3 2 LOCK Input
RAH
and t
ASC
RAH
and t
ASC