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4-8 Theory of Operation
4.3.4 ALI M1523 (PCI, Cache and Memory Controller)
The M1523 is a bridge between PCI and ISA bus, providing full PCI and ISA compatible functions.
The M1523 has Integrated System Peripherals (ISP) on-chip and provides advanced features in the
DMA controller. This chip contains the keyboard controller, real-time clock and IDE master
controller. This chip also supports the Advanced Programmable Interrupt controller (APIC)
interface.
One eight-byte bidirectional line buffer is provided for ISA/DMA master memory read/writes. One
32-bit wide posted-write buffer is provided for PCI memory write cycles to the ISA bus. It also
supports a PCI to ISA IRQ routing table and level-to-edge trigger transfer.
The chip has two extra IRQ lines and one programmable chip select for motherboard Plug and Play
functions. The interrupt lines can be routed to any of the available ISA interrupts.
The on-chip IDE controller supports two IDE connectors for up to four IDE devices providing an
interface for IDE hard disk and CD-ROMs. The ATA bus pins are dedicated to improve the
performance of IDE master.
The M1523 supports the Super Green feature for Intel and Intel compatible CPUs. It implements
programmable hardware events, software event and external switches (for suspend/turbo/ring-in).
The M1523 provides CPU clock control (STPCLKJ). The STPCLKJ can be active (low) or inactive
(high) in turn by throttling control.
A simplified block diagram of the M1523 chip is shown in Figure 4-3 and the associated pinouts are
provided in Figure 4-4.
M1523 Block Diagram
DATA
Buffer
Control
Address
Buffer
Decoder
Clock & Reset
PCI BUS
Interface
UNIT
PCI
Arbiter
Interface
ISA
Interrupt
UNIT
PCI
Interrupt
UNIT
CPU
Interface
USB
Interface
(reserved)
PCI
IDE
Master
Interface
ISA BUS
Interface
UNIT
DMA
Refresh
UNIT
PMU or APIC
Interface
PS2/AT
Keyboard
Controller
Timer
UNIT
MISC.
Logic
REAL
Time
Clock
PWG
CPURST
RSTDRV
OSC14M
PCICLK
CBEJ[3:0]
AD[31:0]
FRAMEJ
TRDYJ
IRDYJ
STOPJ
DEVSELJ
SERRJ
PAR
PHOLDJ
PHLDAJ
FERRJ
IRQ[15:14]
IRQ[11:3]
INTAJ/M1II
NTBJ/S0
INTCJ/S1
INTDJ/S2
IGNNEJ
INTR
NMI
A20MJ
USBCLK
USBP[11:10]
IDRQ[0:1]
IDAKJ[0:1]
IDERDY
IDEIORJ
IDEIOWJ
IDESCS3J
IDESCS1J
IDEPCS3J
IDEPCS1J
IDE_A[2:0]
IDE_D[15:0]
SD[15:8]
XD[7:0]
SA[19:0]
SBHEJ
LA[23:17]
IO16J
M16J
MEMRJ
MEMWJ
AEN
IOCHRDYJ
NOWSJ
IOCHKJ
SYSCLK
BALE
IORJ
IOWJ
SMEMRJ/LMEGJ
SMEMWJ/RTCAS
EXTSW
STPCLKJ
SPKR
SIRQI
XDIR
SPLED
ROMCSJ
SIRQII
RTC32KI
RTC32KII
KBINH/IRQ1
KBCLK/KBCSJ
KBDATA
MSCLK
IRQ12/MDATA
DREQ[7:5]
DREQ[3:0]
DACKJ[7:5]
DACK2J/3J
TC
REFSHJ
Figure 4-3 M1523 Chip Simplified Block Diagram