Macintosh LC III Developer Note
Download it here: Macintosh LC III Developer Note.pdf
This is Apple Computer's own developer documentation for Macintosh LC III, published in 1993. It covers the 114-pin processor-direct slot, its full signal list and its power budget (including the -5 V supply), the Sonora system chip, the VRAM video subsystem and the memory configuration rules.
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.