PALcode
PALcode (Privileged Architecture Library code)[1][2] is the name used by DEC in the Alphainstruction set architecture (ISA) for a set of functions in the System Reference Manual (SRM) or AlphaBIOSfirmware, providing a hardware abstraction layer for system software, covering features such as cache management, translation lookaside buffer (TLB) miss handling, interrupt handling, and exception handling. It evolved from a feature of the DEC PRISM architecture named Epicode.[3]
PALcode is Alpha machine code, running in a special mode[4] that also allows access to internal registers specific to the particular Alpha processor implementation. Thus, it is somewhere between the role of microcode and of a hardware emulator. PALcode is operating system-specific,[5] so different versions of PALcode are required by OpenVMS, Tru64 UNIX, and Windows NT. Tru64 UNIX PALcode is also used by NetBSD, FreeBSD, OpenBSD and Linux.
References
[edit]- ^Alpha Architecture Reference Manual. Digital Press. 2014. ISBN 978-1483294339.
PALcode—Alpha's Very Flexible Privileged Software Library A Privileged Architecture Library (PALcode) is a set of subroutines that ...
- ^"PALcode for Alpha Microprocessors System Design Guide"(PDF). May 2, 1996.
PALcode for Alpha Microprocessors. System Design Guide. May 1996. This guide explains how to use the Privileged Architecture Library code.
- ^Neil Rieck. "Dave Cutler, PRISM, Mica, Emerald, etc". neilrieck.net. Retrieved 2020-12-21.
- ^"PALcode - ES40 Emulator".
PALcode is Alpha machine code, running in a special mode that allows access to internal registers specific to the particular Alpha processor
- ^"The Alpha AXP Processor".
The Alpha AXP architecture uses a set of subroutines, call privileged architecture library code (PALcode). PALcode is specific to the operating system, the CPU ...
External links
[edit]- Hewlett Packard OpenVMS FAQ (archived on May 11, 2011)
- "PALcode for Alpha Microprocessors System Design Guide"(PDF). Digital Equipment Corporation. May 1996. Retrieved November 7, 2013.
- Bruce Hutton. "Some simple PAL code". Archived from the original on July 13, 2015.
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