Although the various Level II ROMs have been disassembled and commented, the Level 1 ROM had not been … until now. To see a commented (as best I could figure out; the floating point routines are very hard to follow) Model I Level 1 ROM disassembly, visit the Model I Level 1 ROM Page.
Special thanks to George and Peter for their excellent Z-80 Debugging features of TRS80GP, or I would never have been able to follow which Register Set was active at which moment.