INTERWRT.BIN     INSTRUCTIONS:    ********************************************
AUTHORIZATION FOR MONTH 1 AT:     0100 MASK + SUBSCRIBER KEY + 000 + A5 MO.

AUTHORIZATION FOR MONTH 2 AT:     0163 MASK + SUBSCRIBER KEY + 000 + A5 MO.

SERIAL NUMBER [FORWARD]   AT:     0235

CURRENT MONTH & SERVICE ID  :     0246 & 0427   EXAMPLE: 22 A5

KEY 00 THROUGH 03 ..........:     2000 FORWARD  EXAMPLE: 

2000: 00 00 00 00 00 00 00 [00] 01 01 01 01 01 01 01 [00] 
      02 02 02 02 02 02 02 [00] 03 03 03 03 03 03 03 [00]

THEORY OF OPERATION: THE WRITER IS THE TYPE THAT THE LIGHT DOES NOT COME ON.
                     THE CLEAR TEXT KEYS AT 2000 ARE ENCRYPTED BY THE WRITER
                     [TRAP 18] AND STORED AT 6740 IN U-20. THE TIER CHIP IN
                     TURN DE-CIPHERS THEM BY A REVERSE TRAP 18 AND USES THE
                     ENCRYPTED KEYS FROM U-20 TO PRODUCE THE WORKING KEY...
                     THIS WAY THERE IS NO CLEAR TEXT KEYS IN U-7, U-20 OR
                     IN U-30 TO BE READ OUT OR COPIED... THE IMPORTANT THING
                     IS THAT THE CRYPTO HEALTH BYTE [FF] IN U-7 BE CORRECT
                     FOR OPERATION........ GOOD LUCK!................DOC

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