Rainbow Electronics T89C5115 User Manual

Page 22

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T89C5115

4128A–8051–04/02

Figure 8. Lower 128 bytes Internal RAM Organization

Upper 128 Bytes RAM

The upper 128 bytes of RAM are accessible from address 80h to FFh using only indirect
addressing mode.

Expanded RAM

The on-chip 256 bytes of expanded RAM (ERAM) are accessible from address 0000h to
00FFh using indirect addressing mode through MOVX instructions. In this address
range.

Note:

Lower 128 bytes RAM, Upper 128 bytes RAM, and expanded RAM are made of volatile
memory cells. This means that the RAM content is indeterminate after power-up and
must then be initialized properly.

Bit-Addressable Space

4 Banks of
8 Registers
R0-R7

30h

7Fh

(Bit Addresses 0-7Fh)

20h

2Fh

18h

1Fh

10h

17h

08h

0Fh

00h

07h