2-22 Service Guide
Table 2-3 M1523 Signal Descriptions (continued)
Signal Pin Type Description
Miscellaneous
MSCLK 154 OMouse Clock Output when the internal KBC is enabled.
RTC32KI 16 IRTC 32.768K Osc1. This is crystal input and requires an
external 32.768khz quartz crystal.
RTC32KII 15 IRTC 32.768K Osc2. This is crystal input and requires an
external 32.768khz quartz crystal.
SIRQI 44 ISteerable IRQ Input 1
SIRQII/IRQ8J 45 ISteerable IRQ Input 2 when the internal RTC is enabled.
RTC interrupt input when the internal RTC is disabled.
USBCLK 46 IUniversal serial bus clock pin (reserved).
USBP1[1:0] 59, 60 I/O Universal serial bus data pin (reserved).
Power Management
EXTSW /
APICREQJ 61 IExternal SMI Switch or APIC Request Input. EXTSW is a
falling edge triggered input to the M1523 showing that an
external device is requesting the system to enter SMM
mode. An external pull-up should be placed on this signal
if it is not used or it is not guaranteed to be always driven.
When external APIC mode is enabled, this pin is
APICREQJ.
SMIJ / APICCSJ 50 OSMM Interrupt or APIC Chip Select. A synchronous
output asserted by the M1523 in response to one of many
enabled hardware or software events. When external APIC
mode is enabled, this pin is APICCSJ.
STPCLKJ /
APICGNTJ 51 OStop CPU Clock Request or APIC Grant Output.
STPCLKJ is connected directly to the CPU and is
synchronous with PCI clock. When external APIC mode is
enabled, this pin is APICGNTJ.
IDE Interface
IDRQ[1:0] 138-137 IIDE DRQ Request for IDE Master
IDAKJ[1:0] 143-142 OIDE DACKJ for IDE Master
IDERDY 141 IIDE Ready
IDEIORJ 140 OIDE IORJ Command
IDEIOWJ 139 OIDE IOWJ Command
IDESCS1J 149 OIDE chip Select for Secondary Channel 0
IDESCS3J 150 OIDE chip Select for Secondary Channel 1
IDEPCS1J 147 OIDE chip Select for Primary Channel 0
IDEPCS3J 148 OIDE chip Select for Primary Channel 1
IDE_A[2:0] 145, 144, 146 OIDE ATA Address Bus