https://github.com/akkartik/mu/blob/master/090register-names.subx
 1 == data
 2 Registers:  # (table string int)
 3   # a table is a stream
 4   0x40/imm32/write
 5   0/imm32/read
 6   0x40/imm32/length
 7   # data
 8   "eax"/imm32  0/imm32
 9   "ecx"/imm32  1/imm32
10   "edx"/imm32  2/imm32
11   "ebx"/imm32  3/imm32
12   "esp"/imm32  4/imm32
13   "ebp"/imm32  5/imm32
14   "esi"/imm32  6/imm32
15   "edi"/imm32  7/imm32