GMS77C1001 datasheet(21/44 Pages) HYNIX

21 / 44 page

GMS77C1000/GMS77C1001

July. 2001 Ver. 1.1

9. MEMORY

The GMS77C1000/1001 has separate memory maps for

program memory and data memory. Program memory can

only be read, not written to. It can be up to 1K words of

program memory. Data memory can be read and written to

32 bytes including special function registers.

9.1 Program Memory

The program memory is organized as 0.5K, 12-bit wide

w o rds(G M S77C1000) and 1K , 12-bit w i de

words(GMS77C1001). The program memory words are

addressed sequentially by a program counter. Increment-

ing at locat ion 1 F F H (G MS7 7 C100 0) or 3F F H

(GMS77C1001) will cause a wrap around to 000H.

Figure 9-1 and Figure 9-2 show a map of program memo-

ry. After reset, CPU begins execution from reset vector

which is stored in address(1FFH: GMS77C1000, 3FFH:

GMS77C1001).

9.2 Data Memory

The data memory consists of 25 bytes of RAM and seven

special function registers. The data memory locations are

addressed directly or indirectly by using FSR.

Figure 9-3 shows a map of data memory. The special func-

tion registers are mapped into the data memory..

FIGURE 9-1 GMS77C1000 PROGRAM MEMORY MAP

AND STACK

PC<8:0>

Stack Level 1

Stack Level 2

Reset Vector

On-chip

Program

Memory

000H

0FFH

100H

1FFH

FIGURE 9-2 GMS77C1001 PROGRAM MEMORY MAP

AND STACK

FIGURE 9-3 GMS77C1000/1 DATA MEMORY MAP

PC<9:0>

Stack Level 1

Stack Level 2

Reset Vector

On-chip

Program

Memory

000H

0FFH

100H

3FFH

On-chip

Program

Memory

2FFH

300H

1FFH

200H

(Page 0)

(Page 1)

0FH

10H

1FH

INDF

TMR0

PCL

STATUS

FSR

00H

01H

02H

03H

04H

05H

06H

File Address

Special

Function

Registers

00H

06H

07H

DATA

MEMORY

(SRAM)

DATA

MEMORY

(SRAM)

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