Lines 175, 180, 185 have some extremely weird structs, that do not make sense in today's C language. Back in 6th Edition C, all struct fields were in the same namespace, so you could use '->lobyte' or '->hibyte' on any pointer you cared to. Good stuff, I'm sure it made for very interesting bugs.
FWIW, some of us still do this in C programs today. Having a relatively unique prefix for struct members makes it extremely easy to find uses of those members with relatively simple tools like cscope.
