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  • Model 4P Bootup Options (Keypresses At Reset/Power On)
  • Model 4P Modem Commands
  • Model 4P Boot ROM Disassembled – Here
    Model 4P Bootup Options (Keypresses At Reset/Power On):
    Whether the Model 4P boots in the Model III or Model 4 mode depends on the key sequence used during the boot. Pressing one of several keys select a different mode of operation. The selected key should be held until the boot sequence is complete. NEVER USE THE <SHIFT>,<CAPS>, OR <CONTROL> KEYS DURING A BOOT SEQUENCE.
    Key         Action
    . Run dynamic RAM test
    V Print boot ROM version
    1, F1 Boot from Hard Disk
    2, F2 Boot from floppy disk only
    3, F3 Boot in Model III mode
    <RIGHT-SHIFT>   RS-232 boot
    P Prompts user to switch disks after booting the Model III ROM image. THis mode can be used to run previous Model III application diskettes that do not contain the ROM image. At the prompt press <BREAK> to run Model III ROM BASIC, press <ENTER> to load and run a Disk Operating System.
    N Indicates to the Model 4P that is is not to boot the ROM image. Use this to boot Model 4 DOSs if ROM has been previously loaded.
    L Load the ROM image even if it has already been loaded. This mode is used to force the Model 4P to load the ROM image in case it has been damaged.
    <BREAK> Set flag at 405BH
    <ENTER> Terminate keyboard routine
    Technical Note: All of this is accomplished by allowing deselection of the boot ROM by adding another port (unavailable in the Model 4). Port 9CH is the BOOT* port. This signal is used to latch Data Bit 0 to produce ROM*. ROM* is used by PAL U109 to produce (or not produce) the ROM chip enable.

    Model 4P Modem Commands
    * Opens modem for programming.
    A Switches modem to the answer mode.
    @ Stand by to receive a new Abort code.
    C Clears (resets) modem memory.
    D Clears current telephone number from memory. Must precede any new telephone number.
    E Toggle the Echo enable switch.
    F Fast Rotary or Tone dialing (20 pps.)
    G Toggle forced carrier detect switch.
    L Transmits (displays) current contents of modem memory to the computer (terminal).
    M Toggles the Manual/Automatic switch.
    O Switches the modem to the Originate mode.
    P Inserts a 3 second pause in dialing sequence.
    Q Puts modem into LOCal Test Mode.
    R Rotary dialing (default value).
    S Slow Rotary or Tone dialing (10 pps.) (default value).
    T Tone dialing (10 digits per second).
    X Executes current program (dials phone number in memory, goes into Self-Test mode, waits for telephone to ring while in answer mode).
    BKSP   Erase the last code entered when programming dialing information.
    , Insert a user space when programming dialing information.
          To see the menu (or list) of the modem you type: *L in the terminal program such as COMM/CMD, XT4/CMD, etc.
    To program it in order to call 555-3595, you would do the following on one line:
         C clears modem
         M changes to automatic
         O is for originate
         G disables forced carrier detect
         F is for Fast dialing
         D is for dialing
         R is for Rotary
    Now if you typed the modem will respond with:
         F CD=N
    then you would type to execute the above commands and dial the number.