W78958B Datasheet, PDF (6/28 Pages) Winbond – 8-BIT EMULATION MICROCONTROLLER

W78958B
P3.7−P3.0 Port 3, Bits 7−0
TYPE
MODE
DESCRIPTION
Advanced
Normal Functions are the same as those in the W78C32.
Emulation Frozen in the original state.
Standard
Normal Functions are the same as those in the W78C52.
Emulation Frozen in the original state.
DP4.7−DP4.0 Address/Data Bus, Bits 7−0
TYPE
MODE
DESCRIPTION
Advanced
Normal DP4 provides a multiplexed low-byte address/data bus during
accesses to external memory.
Emulation
When ESEL is held at "L" level, DP4 is the data input/output of the
SFR/PC and internal RAM. When ESEL is held at "H" level, DP4 is
in high impedance state.
Standard
Normal Pins ROMS1 and ROMS0 determine functions of DP4. For details,
see Table D2.
Emulation Same as in the advanced type.
ROMS1
0
0
1
1
ROMS0
0
1
0
1
FUNCTIONS OF DP4
Provides a multiplexed low-byte address/data bus during accesses to
external 4 KB EPROM.
Provides a multiplexed low-byte address/data bus during accesses to
external 8 KB EPROM.
Provides a multiplexed low-byte address/data bus during accesses to
external 16 KB EPROM.
Provides a multiplexed low-byte address/data bus during accesses to
external 32 KB EPROM.
Table D2.
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