4-8 Theory of Operation
The signal descriptions for the M1521 are provided in Table 4-2. The chip pinouts are
provided in Figure 4-3.
ALI M1521 (PCI, Cache, and Memory Controller)The ALADDIN-III consists of two chips, ALI M1521 and M1523 to give a 586 class
system the complete solution with the most up-to-date feature and architecture for the
new multimedia/multithreading operating system. It utilizes the BGA package to improve
the AC characterization, resolves system bottleneck and make the system manufacturing
easier. The ALADDIN-III gives a highly-integrated system solution and a most up-to-
date system architecture including the UMA, ECC, PBSRAM, SDRAM/BEDO, and
multi-bus with highly efficient, deep FIFO between the buses, such as the HOST/PCI/ISA
dedicated IDE bus.
The M1521 provides a complete integrated solution for the system controller and data
path components in a Pentium-based system. It provides 64-bit CPU bus interface, 32-bit
PCI bus interface, 64/72 DRAM data bus with ECC or parity, secondary cache interface
including pipeline burst SRAM or asynchronous SRAM, PCI master to DRAM interface,
four PCI master arbiters, and a UMA arbiter. The M1521 bus interfaces are designed to
interface with 3V and 5V buses. It directly