OSWORD &7B (123) - Modem comands Prestel Adaptor
The Prestel adapter modem can be in one of five states: State 0 - on-hook, speaker off. State 1 - off-hook, speaker on, modem off. State 2 - off-hook, speaker off, modem off, dialing suitable. State 3 - off-hook, speaker on, modem disabled, checking progress. State 4 - off-hook, speaker off, modem enabled, data must be sent at 75 baud and received at 1200 baud. The modem calls are used to step through the five states and to monitor the dialling progress. On entry: XY?0=command: 0 - RESET to state 0. 1 - STEP to next state. Do not use in state 4. 2 - PULSE. Send a dial pulse. Use in state 2. 3 - START-DIGIT. Initialise to send a digit, use in state 2. 4 - END-DIGIT. Terminate dialling a digit, use in state 2. 5 - DCD-CHECK. Exits with result in XY?0: 0 - unpowered or no carrier 1 - powered in state 0, carrier present in state 4. To dial a number, STEP to state 2, for each digit, START-DIGIT, PULSE for the number, END-DIGIT, STEP to state 4.
OSWORD &7B (123) - Modem commands COMMAND
On entry, XY+0=command as follows: 1 - Read status byte On exit: XY?0: b0=offline/online, b1=XOFF sent, b2=XOFF received, b3=carrier present.
2 - Put byte to modem On entry: XY?1=byte to send
3 - Get byte from mode On exit: XY?0=byte XY?1=255 if valid, 0 if invalid
4 - Put string to modem On entry: XY?1=length XY+2.. contains string
5 - Get string from modem On exit: XY?0=length read XY+1.. contains string
6 - Read from remote computer On entry: XY?1=maximum length XY+2..3=maximum time in centiseconds On exit: XY?0=length of string XY+1.. contains string If RETURN not receieved within the time, a Timout error (103) is generated.
OSWORD &7B (123) - Move a block of memory HDFS
On entry: XY!0=source address XY!4=length XY!8=destination address Works across Tube and between Tube and I/O memory.
Jgharston 13:17, 26 May 2009 (UTC)