Major Chips Description 2-21
Table 2-3 M1523 Signal Descriptions (continued)
Signal Pin Type Description
ISA Interface
SMEMRJ / LMEGJ 176 OISA System Memory Read. When the internal RTC is
enabled, this signal indicates that the memory read cycle
is for an address below 1-MB address. Otherwise, this pin
only indicates an address below 1M byte.
SMEMWJ / RTCAS 174 OISA System Memory Write. When the internal RTC is
enabled, this signal indicates that the memory write cycle
is for an address below 1-MB address. Otherwise, this pin
is used as RTC address strobe.
DREQJ[7:5]
DREQJ[3:0] 38, 34, 30,
186, 166, 189,
25
IDMA Request Signals. These are DMA request input
signals.
DACKJ[7:5] /
DAK_SEL[2:0]
DACKJ[3] / PCSJ,
DACKJ[2] /
DACKOJDACKJ[1],
DACKJ[0]
36,32,
28,
184,
204,
48,
47
O
I/O
O
When DACKJ polling mode is disabled, these pins are
DACKJ[7:5,3:0](O). Otherwise, these pins are
DAK_SEL[2:0](O) connect to external MUX select inputs,
PCSJ(O) programmable chip select, and DACKOJ(O)
connected to external MUX chip enable.
TC 206 ODMA End of Process. Hardware setting options:
Pulled low: Support external I/O APIC mode
Pulled high: Not support external I/O APIC
REFSHJ 191 I/O ISA Refresh Cycle. This signal is input during ISA master
cycles, but an output during other cycles.
Timer
SPKR 43 OSpeaker Output. Hardware setting options:
Pulled low: Enable Internal KBC
Pulled high: Disable Internal KBC
Miscellaneous
SPLED 44 OSpeed LED Output. Hardware setting options:
Pulled low: Enable DMA DACKJ[7:5,3:0]
polling mode
Pulled high: Disable DMA DACKJ[7:5;3:0]
polling mode
ROMCSJ 158 OROM and RTC Chip Select. This signal must be pulled
high for normal operation.
XDIR 159 OX-bus Direction Control. Hardware setting option: must be
pulled high.
KBINH/ IRQ1 151 IKB Inhibit Input when the internal KBC is enabled.
IRQ1 Input when the internal KBC is disabled
KBCLK/ KBCSJ 152 I/O KB interface CLK when the internal KBC is enabled.
KB Chip Select when the internal KBC is disabled
KBDATA 153 OKB interface Data when the internal KBC is enabled.