PSIONICS FILE - DEVICES
=======================
Device driver interfaces
Last modified 1994-09-13
========================

This document describes all known functions for all known device drivers. It
does not include file IO, even when done through the same interfaces.

The device drivers documented are:
  SND: Sound device
  TIM: Timer device
  ALM: Alarm device
  WLD: World device
  TTY: Serial port device
  PAR: Parallel port device
  FRC: Free running counter
  XMD: XModem driver
  YMD: YModem driver
  Console device


Types of device driver
----------------------
On the Series 3, much functionality, including the filing system, is provided
via device drivers. There are three kinds of device drivers:
* physical device drivers: these drive the hardware directly
* base logical device drivers: these provide a basic abstraction for working
  with logical device drivers
* stacked logical device drivers: these provide higher levels of abstraction
Only logical device drivers need to know about physical device drivers; all
user applications operate through logical device drivers.

For example, the 3-Link pod and cable might be accessed through a physical
device driver called TTY.LNK: (all physical device drivers have a two part
name). This is automatically loaded the first time that the logical device
driver TTY: is opened, and TTY: will use it to actually communicate with the
pod.

When TTY: is opened, the kernel will return a handle. Read and write operations
on that handle will send data directly to and from the port. Alternatively,
the XMD: device driver could be stacked on top of TTY: on that handle. Once
this has been done, read and write on that handle will now be done via the XMD:
driver, which wraps the data in the XModem protocol and calls the TTY: driver
to do the actual output. There is no limit to how many device drivers can be
stacked upon one another.


Opening a handle
----------------
A base logical device driver is opened with the IOOPEN keyword or the IoOpen
system call; a stacked logical device driver is opened with IoOpen. The name is
examined to see whether it has a colon as the fourth character but not the
fifth; if so, it is split into a device name and a channel name. The kernel
then checks that the logical device exists; if not, or if the name does not
have the correct form, it prefixes "FIL:" to the name and tries again (FIL
is the filing system logical device driver). For example:
    "SND:"        device "SND"  channel name ""
    "TTY:A"       device "TTY"  channel name "A"
    "FIL:A:XXX"   device "FIL"  channel name "A:XXX"
    "HELLO.TXT"   device "FIL"  channel name "HELLO.TXT"
    "ROM::XXX"    device "FIL"  channel name "ROM::XXX"
    "FIL:TTY:"    device "FIL"  channel name "TTY:"
    "QXV:"        device "FIL"  channel name "QXV:"
[the last example assumes there is no QXV device driver].

The filing system and the FIL: driver are described in the Psionics file
FILEIO. All other known drivers are described here.

IOOPEN and IoOpen are passed a mode to open the device or file. Drivers other
than the filing system and those specifically mentioning it ignore the mode.
It is recommended that a mode of -1 be used, as this is always rejected by the
filing system; thus an error in the device name or a missing driver will be
detected.

A driver may refuse to open a given channel name, or all channels, more than
a certain number of times without closing some first. For example, a TTY
driver might only allow one open handle at a time for each port.


Using the device driver
-----------------------
Once a device driver has been opened, it is accessed with the keywords IOW,
IOA, and IOC (Series 3a only). These keywords offer the same services, and
differ only in the way completion is indicated.

IOW waits until the operation completes, and then returns. No signal is
    generated.
IOA has an extra status variable argument. The variable is set to -46 at the
    start of the operation, and then to the final result when it completes; a
    signal is generated at this moment (it can be collected with IOWAIT or
    IOWAITSTAT). Note that some operations complete immediately, and so the
    status of -46 is never seen.
IOC is like IOA, but if the operation completes immediately, it places the
    result into the status variable and generates a signal. Thus the code
    making the call can check the result in one place (after collecting the
    signal) rather than two (after the call and after the signal).

Each call is passed a function number and two parameters for passing other
information. The latter identify blocks of memory; the actual argument can be
either the name of an OPL variable (typically the first element of an array),
in which case that variable marks the start of the block, or it can be the #
operator applied to the address of the block. The former is equivalent to
#ADDR(variable).

If the parameter is shown as "unused", then any variable or value can be used,
as it will be ignored; it is often convenient to use #0 as such an argument.

Unless stated otherwise, a successful call returns zero, and an unsuccessful
call some non-zero error code.


Standard functions
------------------

These functions apply to all drivers.

Function:   1 (read)
Function:   2 (write)
Argument 1: buffer
Argument 2: count (word)

These functions are equivalent to the IOREAD and IOWRITE keywords. They read
or write up to the specified number of bytes from or to the device; in the
case of function 1, the count is changed to the actual amount read.

These functions can be used with any handle that is using a driver labelled
as a data driver (such as the serial port device or the XModem driver).


Function:   3
Argument 1: unused
Argument 2: unused

This will close the handle; it is equivalent to the IOCLOSE keyword.


Function:   4
Argument 1: unused
Argument 2: unused

This will cancel any uncompleted function on the handle; the function will
complete immediately, with the status variable set to -48 ("I/O cancelled").
A signal will still be generated, and must be collected with IOWAITSTAT or
IOWAIT.


Sound device
------------

The sound device has the name "SND:". There are no channel names.


Function:   1 (sound channel 1)
Function:   2 (sound channel 2)
Argument 1: note information
Argument 2: word holding number of notes
This function is supported by the HC, MC, and Series 3a only.

This plays a sequence of notes on the specified sound channel. The note
information is an array of words, two per note; the first is the frequency of
the note (in Hz), and the second the duration in beats (see function 7).
The sound will not start until both these functions have been called (thus
ensuring the sound is synchronized on both channels). The function completes
when the specified channel finishes playing, even if the other has not.


Function:   7
Argument 1: 2 byte information block
Argument 2: unused

The characteristics of the sound system are set according to the block:
  Offset  0 (byte): beats per minute (2 to 240, default 120)
  Offset  1 (byte): volume (0 max to 5 min)
The beats per minute is only supported by the HC, MC, and Series 3a. On the
Series 3a, volumes 1 and 2 are identical, as are 4 and 5. On the Series 3s,
volumes 0 and 5 are unavailable.


Function:   8
Argument 1: 2 byte information block
Argument 2: unused

The block is filled in with information about the sound channel, using the
same format as function 7.


Function:   9
Argument 1: alarm type (0 = rings, 1 = chimes)
Argument 2: unused

The specified alarm is played; this function completes when the sound has
completely played.


Function:   10
Argument 1: phone number (cstr)
Argument 2: parameter block

This generates DTMF dialling sounds. The number contains the digits to be
dialled (0 to 9, *, #, and A to F can be used; E is the same as *, and F the
same as #). The parameter block has the format:
  Offset 0 (byte): tone length   )
  Offset 1 (byte): delay length  ) all in 1/32 seconds
  Offset 2 (word): pause length  )



Timer device
------------

The timer device has the name "TIM:". There are no channel names.

Function:   1
Argument 1: delay in 1/10 seconds (long)
Argument 2: unused

This will complete after the specified delay. Time when the machine is switched
off is not counted as part of the delay. Changing the system clock will not
affect the completion of this function.


Function:   2
Argument 1: abstime (long)
Argument 2: unused

This will complete at the specified time. If the machine is switched off at
that time, it will switch back on. Changing the system clock will affect the
completion of this function.


Alarm device
------------

The alarm device has the name "ALM:". There are no channel names.

Function:   1 (display date only)
Function:   2 (display date and time)
Argument 1: time specification block
Argument 2: message (cstr)

This schedules an alarm, which causes a message box to be shown at some later
time. The time specification block has the format:
  Offset  0 (long): abstime when the alarm should sound
  Offset  4 (long): abstime to be displayed in the message box
The message (maximum 64 characters) is shown in the message box.

The function completes when the alarm goes off. If the machine is switched off
at that time, it will switch back on. Changing the system clock will affect the
completion of this function.


Function:   10 (display date only)
Function:   11 (display date and time)
Argument 1: time specification block
Argument 2: message (cstr)
These functions are supported by the Series 3a only.

This schedules an alarm, which causes a message box to be shown at some later
time. The time specification block has the format:
  Offset  0 (long): abstime when the alarm should sound
  Offset  4 (long): abstime to be displayed in the message box
  Offset  8 (byte): length of name (L)
  Offset  9 to L+8: name of alarm sound

These functions are identical to functions 1 and 2, except that the alarm sound
is specified by the call. The sound name may be one of the following:
- the name of a sound file; this is searched for in each of:
    A:\WVE\name.WVE
    B:\WVE\name.WVE
    M:\WVE\name.WVE
    ROM::name.WVE
  [This appears to be the search order, but it is not documented.]
  The Series 3a ROM contains the sounds:
    SYS$AL01   Fanfare
    SYS$AL02   Soft bells
    SYS$AL03   Church bell
- a single byte (thus offset 8 is set to 1) with the value 1 (for rings),
  2 (for chimes), or 16 (for silence).


World device
------------

The world device has the name "WLD:". There are no channel names.

This device gives access to the World database. This includes the built-in
database and any one world file. If the World application is running, this is
the file it currently has open. Otherwise it is the last world file to be open.
Several functions use a "city name block". This is a 42 byte block with the
format:
  Offset  0 to 20: name of a city (cstr)
  Offset 21 to 41: name of a country (cstr)
Unless stated otherwise, the country is that in which the city lies.

Many functions establish or use a searching order. This can be set to:
- all cities, in alphabetical order ("city order")
- capital cities, in alphabetical order of country ("country order")
- unspecifed ("random order")
Search order is cyclic: the last city or country is followed by the first.


Function:   10
Argument 1: clue (cstr)
Argument 2: city name block

This locates a city whose name begins with the clue (the search is not case
sensitive, so "lon" will find London, but "ond" will not). If successful, the
city block is filled in with the city, and city order is set.


Function:   11
Argument 1: clue (cstr)
Argument 2: city name block

This locates a country whose name begins with the clue (the search is not case
sensitive, so "lon" will find London, but "ond" will not). If successful, the
city block is filled in with the capital city of the country, and country order
is set.


Function:   12
Argument 1: city name (cstr)
Argument 2: unused

This function succeeds if the city name (ignoring case) is the same as the last
city returned by functions 10, 13, 14, or 15. Random order is set.
@Why ?@


Function:   13 (next city)
Function:   14 (previous city)
Argument 1: city name block
Argument 2: unused

These functions fill the block with the next (or previous) city in the current
search order.


Function:   15
Argument 1: city name block
Argument 2: unused

This function fills the block with the home city; city order is set.


Function:   16
Argument 1: unused
Argument 2: unused

This function sets the home city to the last city returned.


Function:   17
Argument 1: city name block
Argument 2: unused

This function fills the block with the capital city of the default country;
country order is set.


Function:   18
Argument 1: unused
Argument 2: unused

This function sets the default country to that of the last city returned.


  IOW ("WLD:", 19, original, dial_25)
Function:   19
Argument 1: original number (cstr)
Argument 2: diallable number (cstr)

This function generates a diallable number (up to 24 characters) from the
original number, using the following rules:
- all characters before the first digit are stripped from the number;
- the number then ends at the first character other than a digit, space, or the
  special characters * # , and - (star, hash, comma, and dash);
- if there are any spaces or dashes in the number, they are removed and the
  diallable number is modified as follows:
  * if the first digit was a zero, it is removed;
  * if the home city is not in the default country, the sequence is prefixed
    with the international sequence to dial from the home city to the default
    country;
- if not, the number is precisely those characters left.

For example, "abc,123,456xx789" generates "123,456". Assuming that the default
country is the UK and the default city is in the USA, "abc00-34 56x78"
generates "01144003456".


Function:   22
Argument 1: 80 byte buffer
Argument 2: unused

This function fills the buffer with information about the last city returned:
  Offset  0 to  20: (cstr) city name
  Offset 21 to  41: (cstr) country name
  Offset 42 (byte): country time code (see below)
  Offset 43 (byte): DST rule: 0 = none, 2 = European, 4 = North, 8 = South
  Offset 44 (word): minutes ahead of GMT for city
  Offset 46 (word): city latitude in minutes north (negative means south)
  Offset 48 (word): city longtitude in minutes west (negative means east)
  Offset 50 to  66: (cstr) dial code from home city
  Offset 67 to  75: (cstr) area code of city
  Offset 76 (word): X coordinate of city on map (in pixels)
  Offset 78 (word): Y coordinate of city on map (in pixels)

The country time code gives the "central" time in the country. It is an offset
from GMT in units of 30 minutes; for countries behind GMT, 256 is added (or
equivalently, the byte is signed). In practice, this is the time for the
capital city, with the three exceptions of Australia (code 19), Canada, and
the USA (both code $F2 or -14). @Why ?@


Function:   23
Argument 1: 66 byte buffer
Argument 2: unused

This function fills the buffer with information about the country of the last
city returned:
  Offset  0 to  20: (cstr) city name
  Offset 21 to  41: (cstr) country name
  Offset 42 (byte): country time code (see above)
  Offset 43 (byte): DST rule: 0 = none, 2 = European, 4 = North, 8 = South
  Offset 44 (word): minutes ahead of GMT for capital city
  Offset 46 to  50: (cstr) national dialling code
  Offset 51 to  55: (cstr) international dialling code
  Offset 56 to  60: (cstr) country code


Function:   25
Argument 1: city name block
Argument 2: unused

This function returns the next city in the same country as the last city
returned (using city order).


Serial port device (data device)
--------------------------------

The serial port device has the name "TTY:". The channel name is a single
letter from A to Z, identifying the particular port to use. Which ports are
actually provided depends on the specific system.

An open serial port can be read and written with IOREAD and IOWRITE, or with
IOW functions 1 and 2.


Function:   7
Argument 1: 12 byte control block
Argument 2: unused

This function sets various characteristics of the serial port. The control
block has the format:
  Offset  0 (byte): transmit baud rate
  Offset  1 (byte): receive baud rate
    Baud rates are encoded as:
     1 =    50      7 =   600     13 =  4800     19 = 115000
     2 =    75      8 =  1200     14 =  7200
     3 =   110      9 =  1800     15 =  9600
     4 =   134     10 =  2000     16 = 19200
     5 =   150     11 =  2400     17 = 38400
     6 =   300     12 =  3600     18 = 56000
  Offset  2 (byte): framing
    Bits 0 to 3: number of data bits minus 5 (e.g. 3 means 8 bits)
    Bit 4:       clear for 1 stop bit, set for 2 stop bits
    Bit 5:       parity bit enabled if set
  Offset  3 (byte): 0 = no parity, 1 = even parity, 2 = odd parity
  Offset  4 (byte): handshaking
    Bits 0 to 1: 3 = XON handshaking, 0 = no XON handshaking
    Bit 2:       0 = RTS handshaking, 1 = no RTS handshaking
    Bit 3:       1 = DSR handshaking, 0 = no DSR handshaking
    (Any combination of XON, RTS, and DSR can be set at once.)
  Offset  5 (byte): XON character (usually 17)
  Offset  6 (byte): XOFF character (usually 19)
  Offset  7 (byte): flags
    Bit 0: ignore parity errors
  Offset  8 (long): terminating mask
The terminating mask specifies which of the characters with codes 0 to 31
terminate a read. For example, if bits 10 and 13 are set, then a read on the
port will terminate after reading a byte with value 10 or 13.


Function:   8
Argument 1: 12 byte control block
Argument 2: unused

This function fills the control block with the current settings (see function
7).


Function:   9
Argument 1: unused
Argument 2: unused

This function discards any buffered input and any error state. Any handshaking
is set to restart reception.


Function:   10
Argument 1: count (word)
Argument 2: unused

The count is set to the number of bytes buffered and waiting to be read.


Function:   11
Argument 1: 2 byte control block
Argument 2: unused

The first byte of the control block is set to indicate the state of the modem
control lines:
    Bit 0: set if CTS active
    Bit 1: set if DSR active
    Bit 2: set if DCD active

The second byte specifies the new setting for the DTR line:
    0 = leave unchanged
    1 = set DTR active
    2 = set DTR inactive


Function:   12
Argument 1: 6 byte information block
Argument 2: unused

The information block is filled in to indicate which facilites are supported
by the port.
  Offset  0 (long):
    Bit  0: set if supports 50 baud
    Bit  1: set if supports 75 baud
    Bit  2: set if supports 110 baud
    Bit  3: set if supports 134 baud
    Bit  4: set if supports 150 baud
    Bit  5: set if supports 300 baud
    Bit  6: set if supports 600 baud
    Bit  7: set if supports 1200 baud
    Bit  8: set if supports 1800 baud
    Bit  9: set if supports 2000 baud
    Bit 10: set if supports 2400 baud
    Bit 11: set if supports 3600 baud
    Bit 12: set if supports 4800 baud
    Bit 13: set if supports 7200 baud
    Bit 14: set if supports 9600 baud
    Bit 15: set if supports 19200 baud
    Bit 16: set if supports 38400 baud
    Bit 17: set if supports 56000 baud
  Offset  4 (word):
    Bit  0: set if supports 5 bits
    Bit  1: set if supports 6 bits
    Bit  2: set if supports 7 bits
    Bit  3: set if supports 8 bits
    Bit  4: set if supports 2 stop bits
    Bit  5: set if supports even parity
    Bit  6: set if supports odd parity
    Bit  7: set if supports mark parity
    Bit  8: set if supports space parity
    Bit  9: set if supports setting DTR
    Bit 10: set if supports different transmit and receive baud rates
    Bit 11: set if supports soft xon/xoff characters


Parallel port device (data device)
----------------------------------

The parallel port device has the name "PAR:". The channel name is a single
letter from A to Z, identifying the particular port to use. Which ports are
actually provided depends on the specific system. A port will consume power
while open.

An open parallel port can be written with IOWRITE, or with IOW function 2.

No other functions are available on the Series 3.


Free running counter
--------------------

The Free running counter has the name "FRC:". There are no channel names. It
is only available on the Series 3a. Only one process may have the FRC open
at a time, and so it should be closed as soon as possible.

In the following description, an "FRC-tick" is 1/1024 seconds.


Function:   1
Argument 1: (word) set to current count
Argument 2: unused

The current setting of the counter is placed in the word. If the counter is
in mode 1, the count is then reset to zero (the counter continues counting).
This call will not complete while the counter is zero.


Function:   15
Argument 1: (word) operating mode (0 or 1)
Argument 2: (word) step time (10 to 65535)

Starts the counter from zero. Mode 0 means that the counter will increment
every FRC-tick. Mode 1 means that the counter will increment at every N
FRC-ticks, where N is the step time. Any uncompleted function on the counter
will be completed.


XModem and YModem drivers (data device)
---------------------------------------

The XModem driver has the name "XMD:", and the YModem driver the name "YMD:".
There are no channel names. Both are stacked on to another data device.

Once stacked, the driver will use the underlying device to transfer data
using the XModem (single transfer) or YModem (multiple transfer) protocol.
These protocols have a number of variants:
- XModem may use checksums or CRCs on each frame. CRCs are more reliable.
- YModem may use the error correcting or G mode. The G mode does not allow
  errors to be corrected, only detected.
- The transfer may use short frames (128 data bytes) only, or both short and
  long frames (1024 data bytes).

Function 1 is used to receive data. The initial value of the length argument
will be ignored, and a whole frame (128 or 1024) bytes will be placed in the
buffer, which must therefore be large enough. When an end-of-file message is
received, the function will fail with error -36.

Function 2 is used to send data. The length is used as follows:
       0 : an end-of-file message is sent
     128: a short frame is sent
    1024: a long frame is sent
If the length is any other value, the specified amount of data is transferred,
followed by enough $1A bytes to fill a frame (a short frame if the length is
less than 128, and a long frame otherwise).

With YModem, the first frame must be a short frame with the following contents,
in order:
  - (cstr) file name
  - file length in bytes (decimal digits)
  - a single space, then the abstime file last modified (octal digits)
  - a single space, then the file mode, using Unix conventions (octal digits)
  - a single space, then the sending software version number (octal digits)
The last field or fields may be omitted, provided that the name is present.
The rest of the frame must contain only zero bytes. A frame consisting only of
128 zero bytes indicates that there are no more files.


Function:   10
Argument 1: (word) direction: 0 = transmit, 1 = receive
Argument 2: (word) mode

This establishes a connection with the other end of the link. The direction
indicates which way the file transfer will take place. The mode is one of
the following values:
  If long frames are to be rejected while receiving:
    XModem:
      0 = CRC mode if supported by far end, otherwise checksum mode
      1 = CRC mode
      2 = Checksum mode
    YModem:
      3 = Error correcting mode
      4 = G mode
  If long frames are to be accepted while receiving:
    XModem:
      $8001 = CRC mode
    YModem:
      $8003 = Error correcting mode
      $8004 = G mode

With YModem, this function must be called for each file.


Function:   11
Argument 1: unused
Argument 2: unused

This disconnects an existing connection while leaving the driver attached.
With YModem, this function should not be called between files.


Console device
--------------

This is a special device that does not need to be opened; it has the handle -2.


Function:   7
Argument 1: (word) the value 0
Argument 2: (word) style: 0 = normal, 2 = inverse, 4 = underlined, 6 = both

This alters the text style as specified.


Function:   7
Argument 1: (word) the value 2
Argument 2: rectangle

This clears an area described by the rectangle:
  Offset  0 (word): left   coordinate (included)
  Offset  2 (word): top    coordinate (included)
  Offset  4 (word): right  coordinate (excluded)
  Offset  7 (word): bottom coordinate (excluded)


Function:   7
Argument 1: (word) the value 17
Argument 2: control block

This sets the font type for the text window, and (as a side effect) resizes
and moves the current screen (as set by the SCREEN keyword). The control word
has the format:
  Offset  0 (word): font ID plus $3FFF
  Offset  2 (word): style: 0 = normal, 1 = bold, 2 = double size


  IOW (-2, 8, args%(), args%())
Function:   8
Argument 1: information block
Argument 2: must be the same as argument 1

This function places the cursor position, relative to the specified rectangle,
in the information block. This has the format:
  Offset  0 (word): left   limit
  Offset  2 (word): top    limit
  Offset  4 (word): right  limit @why ?@
  Offset  6 (word): bottom limit @why ?@
  Offset  8 (word): set to cursor x coordinate
  Offset 10 (word): set to cursor y coordinate
All coordinates are in character positions, as used by the SCREEN keyword.


Function:   14
Argument 1: array of two words
Argument 2: unused

This function is equivalent to the GETEVENT keyword. The TESTEVENT keyword
also uses this function, testing to see if the status is -46 or not. This
function can be called from OPL programs that are not OPA applications.

@Lots more still in the manual@