Port Allocations
================

HUNTER uses the NSC800 port map for all its I/O functions, including the
keyboard, RS-232, etc. The following gives a list of the most useful
ports which can be controlled from Basic using
:doc:`../basic-functions/out` or
:doc:`../basic-functions/inp` verbs or from machine code.

+-----------------+-----------------+-----------------+-----------------+
| Address Decimal | Hex             | Name            | Description     |
+=================+=================+=================+=================+
| 1               | 1H              | DSR             | Bit seven is    |
|                 |                 |                 | the DSR Input   |
|                 |                 |                 | bit. 1 =        |
|                 |                 |                 | Inactive, 2 =   |
|                 |                 |                 | Active          |
+-----------------+-----------------+-----------------+-----------------+
| 2               | 2H              | INPUTS          | This port has a |
|                 |                 |                 | number of input |
|                 |                 |                 | functions: Bit  |
|                 |                 |                 | 0 is Data In    |
|                 |                 |                 | (Inverted from  |
|                 |                 |                 | RS-232 line).   |
|                 |                 |                 | Bit 1 = DCD.    |
|                 |                 |                 | Bit 2 = Power   |
|                 |                 |                 | low warning (1  |
|                 |                 |                 | = Power O.K., 0 |
|                 |                 |                 | = Power low).   |
|                 |                 |                 | Bit 3 = TXCLK - |
|                 |                 |                 | also the        |
|                 |                 |                 | |SBIP|.         |
+-----------------+-----------------+-----------------+-----------------+
| 96              | 60H             | ANGLE           | Controls        |
|                 |                 |                 | display viewing |
|                 |                 |                 | angle. Input    |
|                 |                 |                 | value in the    |
|                 |                 |                 | range 0-1FH     |
+-----------------+-----------------+-----------------+-----------------+
| 129             | 81H             | V24OUT          | Directly        |
|                 |                 |                 | outputs to the  |
|                 |                 |                 | V24 data line   |
|                 |                 |                 | signal on bit   |
|                 |                 |                 | 0. The output   |
|                 |                 |                 | is voltage      |
|                 |                 |                 | inverted i.e. 0 |
|                 |                 |                 | = +Ve, 1 = -VE  |
+-----------------+-----------------+-----------------+-----------------+
| 130             | 82H             | RTS             | RTS output bit  |
+-----------------+-----------------+-----------------+-----------------+
| 131             | 83H             | POWHLD          | Power control.  |
|                 |                 |                 | bit 0 = 1 :     |
|                 |                 |                 | HUNTER on, bit  |
|                 |                 |                 | 0 = 0 : HUNTER  |
|                 |                 |                 | off             |
+-----------------+-----------------+-----------------+-----------------+
| 132             | 84H             | INVCON          | V24 inverter    |
|                 |                 |                 | control. bit 0  |
|                 |                 |                 | = 1 : Inverter  |
|                 |                 |                 | on, bit 0 = 0:  |
|                 |                 |                 | inverter off    |
+-----------------+-----------------+-----------------+-----------------+
| 133             | 85H             | DTR             | DTR output bit  |
+-----------------+-----------------+-----------------+-----------------+
| 135             | 87H             | AUXPWR          | Turns on the    |
|                 |                 |                 | auxilary power  |
|                 |                 |                 | to pin 10 on    |
|                 |                 |                 | the D type      |
|                 |                 |                 | connector. 1 =  |
|                 |                 |                 | Power on, 0 =   |
|                 |                 |                 | Power off       |
+-----------------+-----------------+-----------------+-----------------+
| 187             | BBH             | ICRPFG          | NSC800 internal |
|                 |                 |                 | interrupt mask  |
|                 |                 |                 | register. See   |
|                 |                 |                 | NSC800 hand     |
|                 |                 |                 | book.           |
+-----------------+-----------------+-----------------+-----------------+
| 224             | EOH             | PAGE            | Memory paging   |
|                 |                 |                 | register        |
+-----------------+-----------------+-----------------+-----------------+

.. |SBIP| replace:: :doc:`single-bit-input-port`