Thread View: comp.arch
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Started by Roderick McConnell
Tue, 26 Jan 1993 09:17
faster internal clocks
Author: Roderick McConnell
Date: Tue, 26 Jan 1993 09:17
Date: Tue, 26 Jan 1993 09:17
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How are faster internal clocks for CPU's typically generated? I am wondering about processors such as the transputer, where the internal clock is a significant multiple of the external clock. The external clock speed can not be varied (for the transputer at least), so my first guess is that there is a PLL inside - but wouldn't that require analog circuitry? -- - Roderick
Re: faster internal clocks
Author: Stephen Doyle
Date: Wed, 27 Jan 1993 09:33
Date: Wed, 27 Jan 1993 09:33
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In article <1993Jan26.091719.17577@irisa.fr> mcconnel@irisa.fr (Roderick McConnell) writes: > > How are faster internal clocks for CPU's typically generated? I am >wondering about processors such as the transputer, where the internal >clock is a significant multiple of the external clock. The external >clock speed can not be varied (for the transputer at least), so my >first guess is that there is a PLL inside - but wouldn't that require >analog circuitry? >-- > - Roderick You're quite right about the transputer using PLL's to increase clock speed, these are implemented in CMOS and internally increase frequency to support up to 30MHz clock cycle and 5x oversampling of the 20Mbit/sec links - the clock input supplied to the transputer must be 5MHz. Steve Steve Doyle, Software Marketing, INMOS Ltd | Tel +44 454 616616 1000 Aztec West | Almondsbury | UK: steved@inmos.co.uk Bristol BS12 4SQ, UK | US: steved@inmos.com
Re: faster internal clocks
Author: Peter Thompson
Date: Wed, 27 Jan 1993 09:43
Date: Wed, 27 Jan 1993 09:43
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Roderick McConnell (mcconnel@irisa.fr) wrote: : How are faster internal clocks for CPU's typically generated? I am : wondering about processors such as the transputer, where the internal : clock is a significant multiple of the external clock. The external : clock speed can not be varied (for the transputer at least), so my : first guess is that there is a PLL inside - but wouldn't that require : analog circuitry? : -- : - Roderick Absolutely correct. -- Peter Thompson JANET: thompson@uk.co.inmos INMOS Ltd UUCP: ukc!inmos!thompson 1000 Aztec West INTERNET: thompson@inmos.co.uk Bristol BS12 4SQ, U.K. Telephone: +44 454 616616
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