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ZX Spectrum 128 edge connector

240 bytes added, 12:57, 10 September 2013
CPU Clock
====CPU Clock====
The !CK signal, sometimes referred to as PHICPU is available on Lower Pin 8. This clock signal is generated by the [[The Spectrum ULA|ULA]] and is interrupted during [[contended memory]] access. This clock signal is inverted by a transistor switch to provide a clean clock edge for the Z80.
This On the [[ZX Spectrum+ 128K|UK 128K]] the ULA clock pin is connected directly to the edge connector and is inverted by TR3 to drive the Z80. On the [[ZX Spectrum +2|+2]] the ULA clock pin is inverted by a NOT gate to generate the clock for the Z80. It is then inverted again by a second NOT gate to generate the edge connector !CK. The !CK signal is '''NOT''' connected on the [[Investronica]] [[ZX Spectrum+ 128K]].

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