Nanoprogram

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The nanoprogram is a switching algorithm that is integrated into a two-stage or multi-stage microprogram execution of a microprogram control unit. The switching algorithm of the command execution is represented by the (predominantly) horizontally coded microcode and can be understood as the superordinate main circuit program of the microprogram control unit. In the case of a (partially) vertically coded instruction execution of the microcode, reference is made to circuit subroutines that are implemented in so-called nanocode and, downstream, control horizontally coded microprogram sequences (vertical displacement).

In the simplest case, the nanoprogram is implemented as a switching algorithm in the form of a switching network, which is integrated into the microcode execution. The nanocode (binary code of the nano command) is used as an input parameter to control decoders and multiplexers in order to activate assigned sub-switching networks for generating the control signals. Ultimately, when executing the nanoprogram, embedded in the higher-level (predominantly) horizontally coded microprogram, a sequence of exclusively horizontally coded microinstruction words with a fixed control bit length is generated. Every single control bit is interpreted as a picos command which is assigned to a control line and whose binary state either blocks or activates the switching process.

literature

  • R. Hoffmann: Computer design: arithmetic units, micro-programming, RISC . 3. Edition. Oldenbourg, Munich 1993, ISBN 978-3-486-22174-9 (especially Chapter 5: Microprogramming, pp. 159-240).
  • W. Oberschelp, G. Vossen: Computer structure and computer structures . 10th edition. Oldenbourg, Munich 2006, ISBN 978-3-486-57849-2 .
  • H. Malz: Computer architecture . 2nd Edition. Vieweg + Teubner, 2004, ISBN 978-3-528-13379-5 .
  • Th. Beierlein, O. Hagenbruch: Pocket book on microprocessor technology . 3rd edition, Hanser Verlag, 2004, ISBN 978-3-446-22072-0 .
  • WK Giloi: Computer architecture . 2nd edition, Springer, 1993, ISBN 978-3-540-56355-6 .