A printer cartridge for electrographic printing (dry or liquid) is provided with two chambers connected by a developer transportation system that traverses a development zone in a first direction. As the toner (developer) from a first of the two compartments is fed through the development zone, excess or unused toner is transported by the developer transportation system into a second of the two compartments. When the first compartment has exhausted its supply of toner, there will be sufficient toner captured in the second compartment to allow for printing capability to be maintained in the system, without any replenishment. The direction of flow of developer during printing is reversed from the second compartment to the first compartment, passing through the development zone.

 
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> Developing apparatus including magnetic field generating means, for use with a developer which includes a magnetic toner component

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