Intel 80C196NU External Memory, Program and Special-purpose Memory, Program Memory in Page FFH

MEMORY PARTITIONS

5.2.1External Memory

Several partitions in pages 00H and FFH and all of pages 01H–0EH are assigned to ext ernal memory (see Table 5-1). Data can be stored in any part of this memory. Instructions can be stored in any part of this memory in 1-Mbyte mode, but can be stored only in page FFH in 64-Kbyte mode. “Memory Configuration Examples” on page 5-27 contains examples of memory configu- rations in the two modes. Chapter 13, “Interfacing with External Memory,” describes the external memory interface and shows additional examples of external memory configurations.

5.2.2Program and Special-purpose Memory

Program memory and special-purpose memory occupy a 4-Kbyte memory partition from FF2000–FF2FFFH. For the 80C196NP and 80C196NU, this partition re sides in external memory (external addresses F2000–F2FFFH). For the 83C 196NP, this partition resides in on-chip ROM in page FFH, and it can also be mapped to page 00H (see “Remapping Internal ROM (83C 196NP Only)” on page 5-22).

5.2.2.1Program Memory in Page FFH

Three partitions in page FFH can be used for program memory:

•FF0100–FF1FFFH in external memory (ext ernal addresses F0100–F1FFFH)

•FF2080–FF2FFFH

—80C196NP and 80C196NU: This partition is in external memory (external addresses F2080–F2FFFH).

—83C196NP: The REMAP bit (CCB1.2), the EA# input, and the type of instruction (extended or nonextended) control access to this partition, as shown in Table 5-2.

Table 5-2. Program Memory Access for the 83C196NP

REMAP	EA# Pin	Instruction Type	Memory Location Accessed
(CCB1.2)
X	Asserted	Extended or nonextended	External memory, F2080–F2FFFH
0	Deasserted	Extended or nonextended	Internal ROM, FF2080–FF2FFFH
1	Deasserted	Extended	Internal ROM, FF2080–FF2FFFH
		Nonextended	External memory, 02080–02FFFH

•FF3000–FFF FFH in external memory (external addresses F3000–FFFFFH)

NOTE

We recommend that you write FFH (the opcode for the RST instruction) to unused program memory locations. This causes a device reset if a program unintentionally begins to execute in unused memory.

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