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

W78958B
ROMS1
0
0
1
1
ROMS0
0
1
0
1
FUNCTIONS OF AP6
AP6<3:0> output the <11:8> address of the external 4K EPROM.
AP6<4:0> output the <12:8> address of the external 8K EPROM.
AP6<5:0> output the <13:8> address of the external 16K EPROM.
AP6<6:0> output the <14:8> address of the external 32K EPROM.
Table D4.
AP7.3−AP7.0 Address Bus, Bit 3−0, Input/Output, Dual-purpose
TYPE
MODE
DESCRIPTION
Advanced Normal Bit 7 of EPMA (Extended Program Memory Address) register
determines functions of AP7<3:0>.
When this bit is "0" (default value), AP7 outputs the <19:16> address of
the external ROM from bits <3:0> of EPMA register during the
execution of "MOVC A,@A+DPTR" to read the external ROM data, the
execution of "MOVX A,@DPTR" to read the external RAM data, or the
execution of "MOVX @DPTR,A" to write the external RAM data.
Excluding those times, AP7<3:0> output 0H.
When this bit is "1," AP7<3:0> (CS3−0) are the output pins to support
memory-mapped peripheral chip select, and only one of them is active
low at any time. These pins are decoded by AP6<7:6>. For details, see
Table D5.
Emulation
When ESEL is held in "L" state, AP7<0> (EWR) and AP7<1> (ERD)
are the write and read control input signals, respectively, for the
accesses to the SFR/PC and internal RAM. When ESEL is held in "H"
state, AP7<3:0> are in high impedance state.
Standard
Normal
AP7<2> (IPME ) is the "internal" program memory enable signal. It
outputs "0" to indicate that the access buses are DP4, AP5 and AP6. It
outputs "1" to indicate that the access buses are Port 0 and Port 2.
Emulation
AP7<3> (IPSEN ) is the "internal" program store output enable signal. It
outputs "0" to enable the "internal" program memory onto the DP4
address/data bus during fetch and MOVC operations.
Same as in the advanced type.
AP6.7
0
0
1
1
AP6.6
0
1
0
1
DESCRIPTION
AP7.0: low; others: high
AP7.1: low; others: high
AP7.2: low; others: high
AP7.3: low; others: high
Table D5.
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