debug: print registers
debug support
disas when debugging
initial stack state
disas I instructions
some line of code in the wrong place
do not set sp in mips.c
x(show mem word) in debugger
disassemble load/store better
delay slot in jal, bal, should set $ra to NPC
I-inst disas, print pc
debugger: goto some address
write(), exit()
print to stderr
libraries
more library and system calls