skip to main content
article
Free Access

Patchable control store for reduced microcode risk in a VLSI VAX microcomputer

Published:01 December 1984Publication History
Skip Abstract Section

Abstract

A VLSI VAX microcomputer, which implements the native VAX computer architecture and instruction set, uses 16K by 40 bits of ROM control store. To decrease the cost of making changes to released microcode, the hardware supports a patching mechanism whereby control flow can be switched between the read-only control memory and a smaller writable control memory. This paper describes the system design considerations that led to the development of the patchable control store, actual implementation of the control store, the effectiveness of the patching scheme, and its impact on system performance.

References

  1. 1 VAX Architecture Reference Manual. Revision 6.1. Digital Equipment Corp., Bedford. Mass., 1982.Google ScholarGoogle Scholar
  2. 2 W.J. Bauer et al., "Read-only Store Patching Methodology." IBM Tech Disel Bulietin. vol. 22, no. 1, pp. 350-2, June. 1979.Google ScholarGoogle Scholar
  3. 3 W.N. Johnson, "A VLSI VAX Chip Set," ISSCC Digest of Technical Papers. pp. 174- 175, 1984.Google ScholarGoogle Scholar
  4. 4 Dileep Bhandarkar. "Architecture Management for Ensuring Software Compatibility in the VAX Family of Computers," IEEE Computer, pp. 87-93. Feb., 1982.Google ScholarGoogle Scholar
  5. 5 D.W. Clark and H.M. Levy. "Measurement and Analysis of Instruction Use in the VAX-11/780." Proc. 9th Annual Symposium on Computer Architecture. vol. 10. no. 3, pp. 9-17. April. 1982. Google ScholarGoogle ScholarDigital LibraryDigital Library

Index Terms

  1. Patchable control store for reduced microcode risk in a VLSI VAX microcomputer

        Recommendations

        Comments

        Login options

        Check if you have access through your login credentials or your institution to get full access on this article.

        Sign in

        Full Access

        PDF Format

        View or Download as a PDF file.

        PDF

        eReader

        View online with eReader.

        eReader
        About Cookies On This Site

        We use cookies to ensure that we give you the best experience on our website.

        Learn more

        Got it!