MA31751
MA31751
Memory Management & Block Protection Unit
Replaces June 1999 version, DS4083-2.0
DS4083-3.0 January 2000
The MA31751 Memory Management Unit/Block Protect
Unit (MMU/BPU) is an optional chip which may be used to
expand the capabilities of the MA31750.
User configurable, the MA31751 can perform as an MMU,
a BPU or both MMU and BPU, conforming to MIL-STD-1750A
and 1750B. MMU mapping and BPU protection for 1M words
of memory is provided by the internal memory. Up to 16
MA31751 devices can be used to give 16M words of logical
mapped onto 8M words of physical address space with
protection in 1750B mode.
The MA31751 is designed to have a simple interface to
both the CPU and the system bus with the minimal number of
control lines. This reduces board space and simplifies system
design.
The MA31751 traps the MMU and BPU XIO commands to
program and read the logical to physical mapping and memory
access control. This provides simple memory management as
defined by the MIL-STD-1750.
CPU
Busses
A[0:15]
AS[0:3]
PS[0:3]
D[0:16]
Bus
Control
OIN
MION
RDWN
ASIN
DSN
PRPEN
MPROEN
GLPE
System
Faults
Chip
Control
Signals
DMAKN
CSN
HITMISSN
BPUVALIDN
EAS
EA[0:10]
FEATURES
s
MlL-STD-1750A/B Compatible
s
Radiation Hard CMOS/SOS Technology
s
User Configurable as Either a Memory Management Unit
(MMU) or a Block Protect Unit (BPU) or Both
s
Memory Management Unit Configuration
• 1 MWord Physical Address Space
• Access Lock and Key of 4K-Word Blocks
• Write/Execute Protection of 4K-Word Blocks
s
Block Protect Unit Configuration
• Protection of 1K-Word Blocks
• Global Memory Write Protection During Initialisation
s
Direct Memory Access Support
System
Signals
RESETN
VDD
GND
MA31751
Figure 1: Chip Control Signals
1/17
DYNEX [ Dynex Semiconductor ]
