Mode 1; Normal Expanded Mode (Mode 2); Development Mode (Mode 3) - Motorola DSP56156 Manual

Operating Mode Summary — Program ROM Part
location of the reset vector in program memory. The reset vector location in Mode 0 is lo-
cated in internal memory at P:$0000; whereas, the reset vector location in Mode 2 is locat-
ed in external memory at P:$E000.
3.2.1.3.2

Mode 1

Mode 1 is the same as mode 0 on the DSP56156ROM part. It is recommended that this
mode not be invoked by the user.
3.2.1.3.3

Normal Expanded Mode (Mode 2)

The normal expanded mode (Mode 2) has the same memory map as Mode 0 and Mode 1
(see Figure 3-2). This mode can be entered by either grounding the MA pin and pulling the
MB pin high or by writing to the OMR and changing the MA and MB bits (s ee Table 3-3).
The reset vector location in Mode 2 is in external program memory at location P:$E000.
3.2.1.3.4

Development Mode (Mode 3)

The development mode is similar to the normal expanded mode except that internal pro-
gram memory is disabled (see Figure 3-2). All references to program memory space are
directed to external program memory, which is accessed on the external data bus. This
mode can be entered by either pulling the MA and MB pins high or by writing to the OMR
and changing the MA and MB bits (see Table 3-3). DSP56156ROM chips with bad or ob-
solete internal program ROM code can be used with external program memory in the
development mode. Reset vectors to program memory location P:$0000.
MOTOROLA OPERATING MODES AND MEMORY SPACES
ROM MEMORY DESCRIPTION
Table 3-3
Operating M M
Mode B A
Single Chip 0 X Internal PROM enabled
External reset at P:$0000
Normal 1 0 Internal PROM enabled
Expanded External reset at P:$E000
Development 1 1 Internal program memory
Expanded disabled
External reset at P:$0000
Description
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