Finished it! Great puzzle, really enjoyed it!
Here's a quick walkthrough guide and explanation of each command for anyone whose stuck:
COMMAND : effect
"signal 0": shows list of devices we can ping. relevant ones are 085 and 237
"manual 7": gives info on how to store data into the memory module.
"manual 8": Tells us 085's password is 1234 and that letters A-Z are encoded as 65-90 and 0-9 are encoded as 101-109.
"signal 255": starts memory input
"signal 1": tells module to store the next data at address 1
"signal 101": tells module to store 101 at address 1 (which encodes to the character 1)
"signal 255"
"signal 2"
"signal 102": stores 102 (character 2) at address 2
"signal 255"
"signal 3"
"signal 103": stores 103 at 3
"signal 255"
"signal 4"
"signal 104": stores 104 at 4
"signal 085 1": passes the password we just stored and stores the response (an image) to address 1
"term 1 IMG 1": displays the img stored at address 1 to terminal 1. shows serial code XAJ4.
"manual 9": tells us how the military encodes passwords. XAJ4 -> UXG2
Then just repeat how we stored 1234 as a password with UXG2 and then ping 237.