A chip-to-chip net is now resolved by (value, strength), not last-writer-
wins, so a real multi-driver bus works: many chips on one data line, only
the enabled one drives, the rest release to Hi-Z.
- busLogic.ts: 4-valued (0/1/Z/X) + drive-strength resolution. Strongest
driver wins; equal strength + opposite = X (contention); no driver = Z;
pull resistor = pull strength. modeToDrive maps VX_OUTPUT -> strong,
VX_INPUT -> Hi-Z (the rom/ram/8255 "release by input" idiom becomes real
tri-state), VX_INPUT_PULLUP/DOWN -> pull.
- busNets.ts: per-net driver registry; resolves and pushes the resolved
level into PinManager; warns once on contention.
- syntheticPins.ts: isSyntheticNetPin distinguishes bus net keys.
- ChipRuntime.ts: pin register/write/set_mode route bus-net pins through
busNets (gated by chipBusEnabled + isSyntheticNetPin); non-bus pins keep
the legacy path; dispose releases the chip's bus drivers. SPICE source
emission is skipped for bus pins (digital fast path beside SPICE).
Tests: busLogic (14), busNets (6, incl. tri-state hand-off + contention),
and the two-real-chip integration now exchanges 0xA5 through the registry.
Full suite 2074 pass with the flag off.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
David Montero Crespo