NEC PD17062 Manuale Utente

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VRAM is the memory that holds data used to select a picture pattern that the IDC displays on a screen such

as a TV screen.  In the 

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PD17062, the VRAM data is allocated at BANK1 and BANK2 in data memory.  One VRAM

data item (8 bits) is held at two adjoining addresses (even and odd address).

BANK1 and BANK2 are each mapped at 112 nibbles of data memory (total of 224 nibbles, or 224 

×

 4 bits).

That is, up to 112 VRAM data items can be specified.

VRAM data consists of 8 bits.  Of the 8 bits, the upper 2 bits are the ID field.  The ID field indicates the type

of VRAM data.  The lower 6 bits are the data field.  The data field contains the display data or control data.

0

1

2

3

4

5

6

7

8

9

A

B

C

D

E

F

0

1

2

3

4

5

6

VRAM data

Column address

Row address

Even

address

Odd 

address

4 bits

4 bits

(2 data memory locations)