Chapter 4 PA-RISC Computer Systems - OpenPA.net

PA-RISC Chipsets Memory and I/O Controller (MIOC)
References
1. Midrange PA-RISC Workstations with Price/Performance Leadership 76 (.pdf) pp. 6-11 Andrew
J. DeBaets and Kathleen M. Wheeler (August 1992: Hewlett-Packard Journal)
2. VLSI Circuits for Low-End and Midrange PA-RISC Computers 77 (.pdf) pp. 12-22 Craig A. Gleason
(August 1992: Hewlett-Packard Journal)
3. High-Performance Design for Low-Cost PA-RISC Desktops 78 (.pdf) pp. 56-63 Craig Fink et al
(August 1992: Hewlett-Packard Journal)
2.5.14 Memory and I/O Controller (MIOC)
The Memory and I/O Controller in the PA-7100LC and PA-7300LC processor integrates DRAM/cache
and I/O controller onto the processor die. It is similar on both CPUs, with the PA-7300LC MIOC
having wider data paths to L2 cache and RAM and supporting the advanced GSC+ bus over the older
GSC.
The integrated memory controller requires only buffers and DRAM modules to build up the complete
memory subsystem. The PA-7300LC memory controller includes a Second Level Cache Controller
(SLC), which provides an optional L2 cache, ranging from 32 KB to 8 MB. It shares the data bus with
the DRAM subsystem, so it has the same width (64/128-bit) and same optional SEDC error control.
Details
� Execution units and internal caches attach on-chip to the MIOC
� External cache (L1 on PA-7100LC, L2 on PA-7300LC) attach to MIOC via 64-bit (PA-7100LC)
or 128-bit (PA-7300LC), both with ECC
� Memory attaches to MIOC via 64-bit (on PA-7100LC) or 128-bit (PA-7300LC), with ECC
� On PA-7300LC memory lines use the L2 cache data lines
� GSC, the system main bus attaches to MIOC
� On PA-7300, GSC+ system main bus
� Support for 4, 16, 64 and 256 Mbit modules
� Support for both FPM and EDO DRAM
� Optional SEDC error control
� Up to 16 physical memory slots
� Support for a wide range of core frequencies
� Support for 3.3 V and 5.0 V DRAM
76 http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1992-08.pdf
77 http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1992-08.pdf
78 http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1992-08.pdf
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