Macintosh Quadra 840AV and Centris 660AV Developer Note
Download it here: Macintosh Quadra 840AV and Centris 660AV Developer Note.pdf
This is Apple Computer's own developer documentation for Macintosh Centris 660AV and Macintosh Quadra 840AV, published in 1993. It covers the AT&T DSP3210 digital signal processor, the Peripheral Subsystem Controller and its DMA channels, the digital audio/video (DAV) expansion connector, the composite and S-video inputs and outputs, the GeoPort serial hardware and the per-slot power budgets.
Apple's developer notes are a different document from the Service Source repair manuals: the Service Source tells a technician which module to swap, while the developer note gives the electrical and architectural detail — rail currents, connector pinouts, power budgets and chip functions — that a repairer needs in order to make a go/no-go measurement. Several figures on this wiki are cited to this document.