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You are here: OSU8 Microprocessor Schematic OSU8 Core Status Bits Register Search PJRC

OSU8 Microprocessor
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CPU Programming
Hardware Info
Schematic
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Status Bits

This schematic contains OSU8's status bits. The four program visible status bits, C (carry), N (negative), Z (zero), P (pointer equal) are stored here. The Carry bit may receive its value from may possible sources, which are mulitplexed here.

OSU8 also specifies four output port bits, which may be loaded from the Carry bit. Those port bit latches and the circuitry to load them from the Carry bit are located in the lower right section of this schematic. OSU8's two input port pins are just inputs the multiplexor that loads the carry bit. Thost two input bits are not latched, they just just copied into the carry bit at the instant that a MOV IN0, C or MOV IN1, C instruction is executed.

Schematic Drawing 8:1 Mux 2:1 Mux


OSU8: Simple 8-Bit Microprocessor Design; Paul Stoffregen
http://www.pjrc.com/tech/osu8/sch/psw.html
Last updated: February 24, 2005
Status: These pages are a work-in-progress
Comments, Suggestions: <paul@pjrc.com>