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The ARM9TDMI processor core implements ARM Architecture v4T, and so executes the ARM 32-bit instruction set and the compressed Thumb 16-bit instruction set. The programmer’s model is fully described in the ARM Architecture Reference Manual.
The ARM v4T architecture specifies a small number of implementation options. The options selected in the ARM9TDMI implementation are listed in the table below. For comparison, the options selected for the ARM7TDMI implementation are also shown:
Table 2.1. ARM9TDMI implementation option
Processor core | ARM architecture | Data abort model | Value stored by direct STR, STRT, STM of PC |
|---|---|---|---|
ARM7TDMI | v4T | Base updated | Address of Inst + 12 |
ARM9TDMI | v4T | Base restored | Address of Inst + 12 |
The ARM9TDMI is code compatible with the ARM7TDMI, with two exceptions:
The ARM9TDMI implements the Base Restored Data Abort model, which significantly simplifies the software data abort handler.
The ARM9TDMI fully implements the instruction set extension spaces added to the ARM (32-bit) instruction set in Architecture v4 and v4T.
These differences are explained in more detail below.
| Copyright © 2000 ARM Limited. All rights reserved. | ARM DDI 0180A |
| Non-Confidential | |
| PDF version | |
| Home > Programmer’s Model > About the programmer’s model |