DSPs: Back to the Future

ABSTRACT

From the dawn of the DSP (digital signal processor), an old quote still echoes: “Oh, no! We’ll have to use state-of-the-art 5µm NMOS!” The speaker’s name is lost in the fog of history, as are many things from the ancient days of 5µm chip design. This quote refers to the first Bell Labs DSP whose mask set in fact underwent a 10 percent linear lithographic shrink to 4.5µm NMOS (N-channel metal oxide semiconductor) channel length and taped out in late 1979 with an aggressive full-custom circuit design. The designer I quoted had realized that the best technology of the time would be required to meet the performance demands of the then cutting-edge digital Touch-Tone receiver.

REFERENCES

• 1: 1. ISSCC Digest of Technical Papers XXII, February 1979.
• 2: 2. ISSCC Digest of Technical Papers XXIII, February 1980.
• 3: 3. Strauss, W. Forward Concepts. Quote supplied for this article.
• 4: 4. Tredennick, N. The death of the DSP. June 6, 2000; see: http://www.ttivanguard.com/dublin/dspdealth.pdf.
• 5: 5. Input samples are memory based rather than from I/O registers because they are reused cyclically.
• 6: 6. Howard Aiken, a WWII computer pioneer, classified processors according to the number of buses used. According to this classification, DSPs aren't "modified" Harvard architectures. They are, in fact, "Class III" Aiken machines.
• 7: 7. How do you pack over 130 instructions into 16 bits? With numerous special registers.
• 8: 8. The next-generation 'C64xx restored multiply-accumulates.
• 9: 9. Speech recognition isn't included in the tally of the worst-case load because it's an offline function.
• 10: 10. Probell, J. Improving application performance with instruction set extensions to embedded processors. DesignCon 2004; see: http://www.ultradatacorp.com/ publications.html.
• 11: 11. Yoshida, J. TI and UB Video get a jump on H.264 decoding. EE Times (December 2, 2002); http: //www.eetimes.com/semi/news/OEG20021202S0048.
• 12: John L. Hennessy , David A. Patterson, Computer architecture (2nd ed.): a quantitative approach, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1996
• 13: 13. See reference 4.

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.5 Sound and Music Computing
          Subjects: Signal analysis, synthesis, and processing

Additional Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.1 Multimedia Information Systems
          Subjects: Audio input/output
      H.5.5 Sound and Music Computing
          Subjects: Systems

General Terms:
Algorithms, Design, Performance