Switched to 10K pulldown instead of 100K pulldown for ISP command handler entry pin on LPC MCU. 100K wasn't enough.
Added 10K pulldown to keep LPC MCU in reset until BBB explicitly asks it to start.
Fixed mistake where I left A/!B channel selection pin floating on the SCC.
The RX pins of the transceiver were wired to the TX pins of the Mini-Din-8 pinout, and vice-versa. This means a straight-through Mini-Din-8 cable would have been needed to connect between a Mac and the cape, which is not typical. Typical printer cables are crossover. This also means that LocalTalk transceivers connected directly to the cape would have had RX and TX backwards.