Mne-

monic

Instruction

Cycles

1st Cycle

2nd Cycle

Operation

Address

(1)

Data

(4 )

Operation

Address

Data

RD

Read

Memory

Array

1+

Write

X

0FFh

Read

(2)

Read

Address

Data

RSR

Read

Status

Register

1+

Write

X

70h

Read

(2)

X

Status

Register

RSIG

Read

Electronic

Signature

3

Write

X

90h

Read

(2)

Signature

Adress

(3)

Signature

EE

Erase

2

Write

X

20h

Write

Block

Address

0D0h

PG

Program

2

Write

X

40h or 10h

Write

Address

Data Input

CLRS

Clear

Status

Register

1

Write

X

50h

ES

Erase

Suspend

1

Write

X

0B0h

ER

Erase

Resume

1

Write

X

0D0h

Notes: 1. X = Don’t Care.

2. The first cycle of the RD, RSR or RSIG instruction is followed by read operations to read memory array, Status Register

or Electronic Signature codes. Any number of Read cycle can occur after one command cycle.

ignored.

4. When word organization is used, upper byte is don’t care for command input.

Table 5. Instructions

Hex Code

Command

00h

Invalid/Reserved

10h

Alternative Program Set-up

20h

Erase Set-up

40h

Program Set-up

50h

Clear Status Register

70h

Read Status Register

90h

Read Electronic Signature

0B0h

Erase Suspend

0D0h

Erase Resume/Erase Confirm

0FFh

Read Array

Table 6. Commands

Blocks

Erasure of the memories is in blocks. There are 7

blocks in the memory address space, one Boot

Block of 16K Bytes or 8K Words, two ’Key Parame-

ter Blocks’ of 8K Bytes or 4K Words, one ’Main

Block’ of 96K Bytes or 48K Words, and three ’Main

Blocks’ of 128KBytes or 64K Words. The M28F410

memory has the Boot Block at the top of the mem-

ory address space (3FFFFh) and the M28F420

locates the Boot Block starting at the bottom

(00000h). Erasure of each block takes typically 1

second and each block can be programmed and

erased over 100,000 cycles.

The Boot Block is hardware protected from acci-

dental programming or erasure depending on the

RP signal. Program/Erase commands in the Boot

Block are executed only when RP is at 12V. Block

erasure may be suspended while data is read from

other blocks of the memory, then resumed.

Bus Operations

Six operationscan be performed by the appropriate

bus cycles, Read Byte or Word from the Array,

Read Electronic Signature, Output Disable,

Standby, Power Down and Write the Command of

an Instruction.

Command Interface

Commands can be written to a Command Interface

(C.I.) latch to perform read, programming, erasure

and to monitor the memory’s status. When power

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M28F410, M28F420