Configuration Byte Location Selector (Ucon) - Intel 8XC251SA User Manual

DEVICE CONFIGURATION
4.4

CONFIGURATION BYTE LOCATION SELECTOR (UCON)

The Configuration Byte Location Selector (UCON) applies only to OTPROM and EPROM prod-
ucts. In conjunction with EA#, UCON specifies whether the configuration array is accessed from
on-chip memory or external memory.
If the UCON bit is clear (e.g., UCON=0), the configuration array is fetched from on-chip nonvol-
atile memory at addresses FF:FFF8H to FF:FFFFH. The configuration bytes are located at loca-
tions FF:FFF8H and FF:FFF9H.
If UCON is set (e.g., UCON=1), the state of the EA# pin at device reset determines whether the
configuration array is accessed from on-chip memory or external memory. If EA# is connected
to V , the configuration array is accessed from on-chip nonvolatile memory at addresses
CC
FF:FFF8H through FF:FFFFH (same as for UCON=0). If EA# is connected to V , the configu-
SS
ration array is obtained from external memory (e.g., a 27512 EPROM).
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