Intel 8XC251SA, User Manual

Page: 71 / 458

4-7
DEVICE CONFIGURATION
Figure 4-4. Configuration Byte UCONFIG1
UCONFIG1
(1), (3)
Address:FF:FFF9H (2)
7 0
— — — INTR WSB WSB1# WSB0# EMAP#
Bit
Number
Bit
Mnemonic
Function
7:5 — Reserved for internal or future use. Set these bits when programming
UCONFIG1.
4 INTR Interrupt Mode:
If this bit is set, interrupts push 4 bytes onto the stack (the 3 bytes of the PC
and PSW1). If this bit is clear, interrupts push the 2 lower bytes of the PC
onto the stack. See 4.8, “Interrupt Mode (INTR).”
3 WSB Wait State B. Use only for A-step compatibility:
Clear this bit to generate one external wait state for memory region 01:. Set
this bit for no wait states for region 01:.
2:1 WSB1:0# External Wait State B (Region 01:):
WSB1# WSB0#
0 0 Inserts 3 wait states for region 01:
0 1 Inserts 2 wait states for region 01:
1 0 Inserts 1 wait state for region 01:
1 1 Zero wait states for region 01:
0 EMAP# EPROM Map:
For devices with 16 Kbytes of on-chip code memory, clear this bit to map the
upper half of on-chip code memory to region 00: (data memory). Maps
FF:2000H–FF:3FFFH to 00:E000H–00:FFFFH. If this bit is set, mapping
does not occur and addresses in the range 00:E000H–00:FFFFH
access
external RAM. See 4.7, “Mapping On-chip Code Memory to Data Memory
(EMAP#).”
NOTES:
1.
User configuration bytes UCONFIG0 and UCONFIG1 define the configuration of the 8XC251S x .
2. Address. UCONFIG1 is the second-lowest byte of the 8-byte configuration array. As determined by
UCON and EA#, the 8XC251SA, SB, SP, SQ fetches configuration information from on-chip nonvolatile
memory at addresses FF:FFF8H and FF:FFF9H or from external memory using these same
addresses. In external memory, configuration information is obtained from an 8-byte configuration
array located at the highest addresses implemented. The physical location of the configuration array in
external memory depends on the size and decode arrangement of the external memory (Table 4-1 and
Figure 4-2).
3. Instructions for programming and verifying on-chip configuration bytes are given in Chapter 14.