MEMORY PARTITIONS

4.1.4Special-purpose Memory

Special-purpose memory resides in locations 2000–207FH (Table 4-2). It contains several re- served memory locations, the chip configuration bytes (CCBs), and vectors for both peripheral transaction server (PTS) and standard interrupts. Accesses to this address range are directed to internal memory if EA# is held high and to external memory if EA# is held low. For devices with- out internal nonvolatile memory, the EA# signal must be tied low. EA# is latched at reset.

Table 4-2. Special-purpose Memory Addresses

Hex Address

Description

 

 

207F

Reserved (each byte must contain FFH)

205E

 

205D

PTS vectors

2040

 

203F

Upper interrupt vectors

2030

 

202F

Security key

2020

 

201F

Reserved (must contain 20H)

201E

Reserved (must contain FFH)

201D

Reserved (must contain 20H)

201C

Reserved (must contain FFH)

201B

Reserved (must contain 20H)

201A

CCB1

2019

Reserved (must contain 20H)

2018

CCB0

2017

Reserved (each byte must contain FFH)

2014

 

2013

Lower interrupt vectors

2000

 

4.1.4.1Reserved Memory Locations

Several memory locations are reserved for testing or for use in future products. Do not read or write these locations except to initialize them. The function or contents of these locations may change in future revisions; software that uses reserved locations may not function properly. Al- ways initialize reserved locations to the values listed in Table 4-2.

4.1.4.2Interrupt and PTS Vectors

The upper and lower interrupt vectors contain the addresses of the interrupt service routines. The peripheral transaction server (PTS) vectors contain the addresses of the PTS control blocks. See Chapter 5, “Standard and PTS Interrupts,” for more information on interrupt and PTS vectors.

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Intel 8XC196MC, 8XC196MD manual Special-purpose Memory Addresses, Reserved Memory Locations, Interrupt and PTS Vectors