M66220 查看數據表（PDF） - Mitsumi

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M66220

256 × 8-BIT MAIL-BOX

Mitsumi 

MITSUBISHI 〈DIGITAL ASSP〉

M66220SP/FP

256 × 8-BIT MAIL-BOX

Arbitration Function and Port Access

Contention No.1 (Address control)

Table 3 gives the port access states and the Not Ready signal output

states if the same address is selected in shared memory by an address

input set from A and B ports with CSA = CSB = “L”.

Table 3 Contention Processing by Address Input

Address setting when selecting

same address

First-in A port

First-in B port

First-in A port

First-in B port

First-in A port

First-in B port

First-in A port

First-in B port

Simultaneous A and B ports

A port

Mode setting

Access

Not Ready A

Read

,

H

Read

,

L

Read

,

H

Read

,

L

Write

,

H

Write

×

L

Write

,

H

Write

×

L

Arbitration Resolved

CSA = CSB = “L”

Mode setting

Read

Read

Write

Write

Read

Read

Write

Write

B port

Access

,

,

×

,

,

,

×

,

Not Ready B

L

H

L

H

L

H

L

H

Arbitration Resolved

Contention No.2 (CS control)

Table 4 gives the port access states and the Not Ready signal output

states when setting the CS inputs from A and B ports valid, and

selecting the same address in shared memory with A0A to A7A=A0B

to A7B.

Table 4 Contention Processing by CS Input

CS input set when selecting

same address

First-in A port

First-in B port

First-in A port

First-in B port

First-in A port

First-in B port

First-in A port

First-in B port

Simultaneous A and B ports

A port

Mode setting

Access

Not Ready A

Read

,

H

Read

,

L

Read

,

H

Read

,

L

Write

,

H

Write

×

L

Write

,

H

Write

×

L

Arbitration Resolved

Note 2: “H” = High level, “L” = Low level

A0A ~ A7A = A0B ~ A7B

B port

Mode setting

Access

Not Ready B

Read

,

L

Read

,

H

Write

×

L

Write

,

H

Read

,

L

Read

,

H

Write

×

L

Write

,

H

Arbitration Resolved

4

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