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Functions Reference Manual for the ONEFOSsil Developer
(c) Copyright 1995-96 by Carl Morris and Morris Softronics
ONEFOSsil, A low level serial communications driver for MS-DOS based
FOSSIL 5 compliant applications.
Introduction
This document is for developers wanting to use ONEFOSsil specific
features and for developers just learning about the FOSSIL
specification. ONEFOSsil supports most FOSSIL 5 and X00 extended
functions, and this document will help describe any differences.
Portions of this document are copyright by VEP Software, Rick Moore, and
Raymond Gwinn. The rest of this document is copyright by Morris
Softronics and Carl Morris.
This documentation is distributed as is and is provided with no
guarantees. You use the information contained within at your own risk.
What is ONEFOSsil and a FOSSIL driver?
ONEFOSsil is a simplified serial communications driver for 8250 series
UART's and MS-DOS based machines running applications requiring a simple
FOSSIL 5 communications driver. ONEFOSsil only provides FOSSIL based
services.
FOSSIL is an acronym derived from Fido Opus Seadog Standard Interface
Layer. The FOSSIL specification was intended to permit machine
independent software (Fido, Opus, and Seadog at the time) to be created
and ran on any MS-DOS based 8086 based computer that had a FOSSIL
compatible driver. Those days are much over, and FOSSIL compatible
drivers are only used as a low level communications interface for
application software. A better specification is needed to keep up with
today's quickly changing world, though.
ONEFOSsil does not maintain total compatibility with the FOSSIL 5
specification. These differences will be noted in this document, but
will seldom cause problems with most modern software.
Interface
ONEFOSsil's Application Program Interface is partly based on the PC BIOS
communications interface. As such, the driver will be entered with an
8086 instruction INT 14h. A function number is passed in 8086 register
AH and other registers are used as needed. Return codes from functions
will very from function to function, and is one of the most confusing
aspect of FOSSIL programming; they're not logical!
Registers are not modified by ONEFOSsil unless otherwise specified.
Note that this is not true about all FOSSIL drivers. While this
document covers basic FOSSIL functions, some differences will be
encountered from FOSSIL to FOSSIL.
In most cases, functions will require a port number to operate. In all
cases, port numbers are passed in register DX. Most FOSSIL's only
support ports 0 - 7. FOSSIL to DigiBoard converters usually only
support 0 - 15. ONEFOSsil supports ports 0 - 63. Notice that in most
cases, the port number is one less than the COM port number; but, in
most FOSSIL's, the port can be specified on any address/irq combination,
or may not even map to a COM port at all.
As a note to developers, FOSSIL functions should not be called in a way
that could cause active code to be reentered. ONEFOSsil and many other
FOSSIL's are re-entrant, but not to that great of a degree.
Detection
Detecting FOSSIL drivers vary. The FOSSIL specification states that to
detect a FOSSIL, one should look at the 6th byte (3rd word) after the
start of the INT 14h service routine for the word 1954h, followed by a
byte, the maximum function supported by the FOSSIL driver. However,
this is unreliable if other utilities and/or drivers have hooked the INT
14h interrupt vector since the FOSSIL was loaded. It is not suggested
to use this method. Instead, it is better to just make the call to the
"Activate" function 04h and check its return codes. Almost all current
applications detect the FOSSIL in this way. Another method, which only
works for a few drivers, is to call the "Information" function, and
check its return codes. X00 only works correctly if the FOSSIL port
called is active. ONEFOSsil and BNU work all the time. Refer to
function 1Bh for more information on the "Information" function,;
however, this method is not suggested either.
Functions
The following functions are supported by most FOSSIL drivers.
Function 00h - Set communications baud, parity, etc.
Input:
AH = 00h
AL = Communications parameters:
010----- = 300 baud
011----- = 600 baud
100----- = 1200 baud
101----- = 2400 baud
110----- = 4800 baud
111----- = 9600 baud
000----- = 19200 baud (replaces IBM 110 baud setting)
001----- = 38400 baud (replaces IBM 150 baud setting)
----0--- = No parity
---01--- = Odd parity
---11--- = Even parity
-----0-- = 1 stop bit;
-----1-- = 1½ bits for 5-bit byte length, 2 for all others
------00 = 5 bits
------01 = 6 bits
------10 = 7 bits
------11 = 8 bits
DX = Port number
Output:
AH = Line status (see function 03h)
AL = Modem status (see function 03h)
This function is identical to the IBM PC INT 14h BIOS call except
that 110 baud and 150 baud have been replaced by 19200 baud and
38400 baud respectively. See function 1Eh for an enhanced version
of this function. In addition, once function 1Eh has been used,
this function will not change the baud rate until function 04h is
used to reactivate the FOSSIL driver.
Function 01h - Transmit character with wait.
Input:
AH = 01h
AL = Output character
DX = Port number
Output:
AH = Line status (see function 03h)
1------- = Time-out occurred, all other bits void
0------- = Character buffered, all bits valid
AL = Modem status (see function 03h, void if time-out occurred)
If there is no room in the transmit buffer, this function will
wait until there is room in the buffer or until a time-out occurs.
Notes:
■ X00 executes functions with the interrupt mask set as it was
when entered. That is, if X00 is called with interrupts
masked, interrupts will remain masked during the processing of
the function. If this function is called with interrupts
masked, it may never return.
■ ONEFOSsil always enables interrupts upon the beginning of every
FOSSIL call, so unless there are severe hardware problems,
ONEFOSsil should always return.
■ It is suggested that applications use function 1Bh instead of
this function in all cases. This function is slow, and X00 and
BNU are prone to lock-ups. Even if the THRE bit is set in a
status return, there is a chance that the buffer could be
filled by another application between calls, and as such the
correct application would get a long, unnecessary delay before
control is returned.
■ Many applications do not check the returned status for a
time-out condition, and as such drop characters when time-outs
occur.
Function 02h - Get received character with wait.
Input:
AH = 02h
DX = Port number
Output:
AH = Line status (see function 03h)
1------- = Time-out occurred, all other bits void
0------- = Character returned, all bits valid
AL = Input character (if no time-out occurred)
If no character is available from the receive buffer, this
function will wait until a character is received or until a
time-out occurs.
Notes:
■ X00 executes functions with the interrupt mask set as it was
when entered. That is, if X00 is called with interrupts
masked, interrupts will remain masked during the processing of
the function. If this function is called with interrupts
masked, it may never return.
■ ONEFOSsil always enables interrupts upon the beginning of every
FOSSIL call, so unless there are severe hardware problems,
ONEFOSsil should always return.
■ It is suggested that applications do not use this function. It
is slow, and X00 and BNU are prone to lock-ups. Even if the
RDA bit is set in a status return, it is possible that another
application could steal the character, leaving the correct
application to wait for the next character or a time-out. It
is suggested that function 18h be used instead. Function 18h
always returns immediately. Sample code for calling this block
function in a single character mode can be found in the
applications notes. Also, X00 and ONEFOSsil support a "get
character with no wait" at function 20h, but is not supported
by the FOSSIL 5 specification or most other FOSSIL's.
Function 03h - Return serial port status.
Input:
AH = 03h
DX = Port number
Output:
AH = Line Status (resembles the 8250 Line Status Register)
1------- = time-out, all other bits in AH and AL void*
-1------ = TSRE, output buffer is empty*
--1----- = THRE, room is available in output buffer*
---1---- = BRK, break detected (since last return)
----1--- = FE, framing error detected (since last return)
-----1-- = PE, parity error detected (since last return)
------1- = OE, the input buffer has overrun (since last
return)*
-------1 = RDA, received data is available in buffer*
AL = Modem Status (resembles the 8250 Modem Status Register)
1------- = Data carrier detect (DCD)*
-1------ = Ring indicator (RI)
--1----- = Data set ready (DSR)
---1---- = Clear to send (CTS)
----1--- = Always set to 1 upon return (dummy DCD)*
----1--- = Delta data carrier detect (since last return)
-----1-- = Trailing edge ring indicator (since last return)
------1- = Delta data set ready (since last return)
-------1 = Delta clear to send (since last return)
* Denotes formal FOSSIL 5 specified bits.
The FOSSIL Specification calls for the delta data carrier detect
bit to always be set as to act as a dummy DCD. If an application
needs a dummy DCD, it should implement it internally as described
in the notes below. As such ONEFOSsil does not support it and
instead uses the bit as a Delta Data Carrier Detect. ONEFOSsil
instead includes a command line option to fake Data Carrier
Detect.
Notes:
■ All bits without asterisks (*) will vary in meaning from FOSSIL
to FOSSIL driver.
■ X00 does not attempt to accurately return the Delta bits.
ONEFOSsil should correctly return the status of the Delta bits.
■ One way to implement a dummy DCD is to check the DCD at the
start of the connection. If DCD is active, the real DCD should
be watched. If DCD is inactive, it should be assumed that
there might never be a DCD, and assume an internal dummy DCD.
If DCD was to go active at some later time, real DCD watching
should be re-enabled and used from there out.
Function 04h - Activate Port.
Input:
AH = 04h
BX = 0h (in case the FOSSIL supports Control-C flagging)
DX = Port number
Output:
AX = 1954h if successful
BL = Maximum function number supported
BH = Revision of FOSSIL specification supported
This function instructs the FOSSIL driver to initialize itself for
communications on the specified port. Buffers will be cleared,
interrupts activated, and DTR raised. If the port can not be
supported, the call goes to the next driver or to the system BIOS.
The FOSSIL specification states that the port parameters are not
to be initialized at this time. However, with ONEFOSsil, if port
parameters have been locked on the command line, they will be
loaded during this time.
The FOSSIL specification calls for an optional Control-C flag, and
is not supported by X00 or ONEFOSsil. As such, BX should be
cleared to prevent any possibility of this occurring.
X00 incorrectly returns the maximum function number (or it isn't
documented.) BNU and ONEFOSsil will only return the maximum
function (currently 20h in ONEFOSsil.)
Multiple calls to this function will repeat the above process as
if the port had not been open. If you want to insure the port is
closed before opening, call function 05h first (many BBS's and
doors do this.)
Notes:
■ At some future date, Ray Gwinn intends to make this function
identical to the PS/2's function 04h. Function 1Ch is a
duplicate of this function. It is my intention to create a new
standard that will support this, and permit much better
communications over all devices available. I do not; however,
have any opinion on which call should be made. The latest X00
and VX00 still support both functions.
Function 05h - Deactivate Port.
Input:
AH = 05h
DX = Port number
Output:
Nothing
This function instructs the FOSSIL that it should no longer
process calls for specified port using the FOSSIL specification.
This function is passed on to the next driver if the port is not
active. Any additional calls to this driver with the specified
port will also be sent on the next driver or the PC BIOS. Any
function not needing a port number, or an active port, will be
processed by most FOSSIL drivers. X00 will not process
"Information" requests if the port requested is not active.
ONEFOSsil will attempt to flush the buffers before this function
will return. ONEFOSsil will return if a time-out occurs, after
deactivating the port. This is to help buggy software that
deactivate the port before all of their "closing" screen has been
sent. It should be assumed however that what is in the transmit
buffer will be lost when this function is called.
NOTICE: At some future date, Ray Gwinn intends to make this
function identical to the PS/2's function 05h. Function 1Dh is a
duplicate of this function. It is my intention to create a new
standard that will support this, and permit much better
communications over all devices available. I do not; however,
have any opinion on which call should be made. The latest X00 and
VX00 still support both functions.
Function 06h - Raise/lower DTR.
Input:
AH = 06h
AL = DTR state to set
DX = Port number
Output:
Nothing
This function is used to control the DTR signal. AL is defined as
follows:
00h = lower DTR
01h = raise DTR
No other function (except functions 04h, 1Ch, and 1Fh) will alter
DTR.
Function 07h - Return timer tick information.
Input:
AH = 07h
Output:
AL = Timer tick interrupt number (1Ch or 08h)
AH = Approximate interrupts per second (18 on IBM)
DX = Approximate number of milliseconds per tick (55)
This function is used to determine the characteristic of the timer
tick for the computer.
The FOSSIL specification says this function is to return the
interrupt number, not the vector. However, most FOSSIL's seem to
return the vector. ONEFOSsil also returns the vector, 1Ch.
This function useless today. I would instead like to see some
functions that do the timing internally, including calculating the
time in seconds for the application. There would need to be 5 or
6 timers in each port, to allow both BBS's and DOOR software to do
separate timing. BBS and DOOR software could use a single
downward counter/timer for time left on-line, but to actually see
software implement this would be a miracle.
Function 08h - Flush output buffer.
Input:
AH = 08h
DX = Port number
Output:
Nothing
This function is used to wait until all pending output has been
transmitted. It does not return until all buffered output has
been sent.
This function should be used with care. Flow control can cause
the system to hang in a tight un-interruptible loop given the
right circumstances.
Note: X00 executes functions with the interrupt mask set as it
was when entered. That is, if X00 is called with interrupts
masked, interrupts will remain masked during the processing of the
function. If this function is called with interrupts masked, it
may never return.
ONEFOSsil will not wait indefinitely and always enables
interrupts. ONEFOSsil will return if no output has been
transmitted in the time-out period. There is no status returned
to notify the application of this condition.
ONEFOSsil's deactivate function literally calls this function to
flush the output buffer.
It is advised that this function NOT be used due to the problems
that could arise. Instead developers are asked to use function
03h and wait in their own loop while the TSRE bit is clear. This
would permit the application to keep an eye on local keyboard
activity among other things.
Function 09h - Purge output buffer.
Input:
AH = 09h
DX = Port number
Output:
Nothing
This function is used to remove any buffered output (transmit)
data. Any output data remaining in the output buffer (not
transmitted yet) is discarded.
Function 0Ah - Purge input buffer.
Input:
AH = 0Ah
DX = Port number
Output:
Nothing
This function is used to remove any buffered input (received) data. Any
input data which is in the receive buffer is discarded.
Function 0Bh - Transmit no wait.
Input:
AH = 0Bh
AL = Character
DX = Port number
Output:
AX > 0000h - Character was buffered for transmission
= 0000h - Character was not buffered
This function performs the same operation as function 01h except
control is returned even if there is no room in the buffer.
It is requested that developers use this function for single
character transmissions. It is asked that you also look into
using function 19h which can transmit more than one character at a
time.
Function 0Ch - Non-destructive read-ahead (Peek).
Input:
AH = 0Ch
DX = Port number
Output:
AH = 00h if a character is available
> 00h if no character is available
AL = Next character if available
This function returns the next character from the receive buffer.
The character returned remains in the receive buffer. Some
programmers call this function "peek".
The extended function 20h is a destructive read without wait.
Function 0Dh - Keyboard peek without wait.
Input:
AH = 0Dh
Output:
AX = IBM-style scan code if available
= 0FFFFh if no character is available
This function returns the keyboard scan code of the next character
from the keyboard. This is a non-destructive (peek) read of the
keyboard.
This function should not be used by IBM PC software.
Function 0Eh - Keyboard read with wait.
Input:
AH = 0Eh
Output:
AX = Keyboard scan code
This function returns the next character available from the
keyboard. If no keyboard input is available, this function waits
until a keyboard character is available. Returned character codes
are the same as function 0Dh (IBM style scan codes).
This function should not be used by IBM PC software.
Function 0Fh - Flow Control for serial I/O.
Input:
AH = 0Fh
AL = Bit defining the flow control to use
DX = Port number
Output:
Nothing
Two kinds of basic flow control are supported. One is software,
called Xon/Xoff flow control. The other is hardware, called
RTS/CTS flow control. Both software and hardware flow control may
be enabled and used at the same time.
The bits passed in AL are defined as follows:
Bit 0 = 1 Enable receiving of Xon/Xoff
Bit 1 = 1 Enable RTS/CTS flow control
Bit 2 Reserved (should be zero)
Bit 3 = 1 Enable transmitting of Xon/Xoff
The FOSSIL specification states that all other bits should be set
to 1 for future expansion. This is insane, as it might enable
options the application doesn't want. It is simpler to assume
that if the bit is not used now, you wont need to use it later and
leave it cleared.
ONEFOSsil permits controlling and locking these options on the
command line. As such, a request to enable or disable a flow
control may not be honored.
Some other FOSSIL drivers automatically lock RTS/CTS if the baud
rate or data parameters are locked on the command line.
Function 10h - Control-C/K checking and transmitter control.
Input:
AH = 10h
AL = Control bits (defined below)
DX = Port number
Output:
AX = 0001h - A Control-C/K has been received
= 0000h - A Control-C/K has not been received
This is primarily used for BBS operation. A bit mask is passed in
AL with the following flags:
Bit 0 = 1 Enable Control-C/K checking
Bit 1 = 1 Disable the transmitter
The Control-C/K status is only returned as long as Control-C/K
checking is enabled. The status is cleared after each call.
The transmitter disable bit lets the application program inhibit
the transmitter. FIFO's of 16550's can not be stopped, and will
continue to transmit until empty.
The disable of the transmitter is not absolute. Several internal
functions can cause the transmitter to be re-enabled, such as
attempting to store another character in the buffer. Some
FOSSIL's will also re-enable the transmitter when they receive an
Xon, but ONEFOSsil does not.
Function 11h - Set current cursor location.
Input:
AH = 11h
DH = Row (line)
DL = Column
Output:
Nothing
This function is exactly like INT 10h, sub-function 2, on the IBM
PC. The row and column are relative to zero. That is, the home
position on the screen is row 0, column 0.
This function should not be used by IBM PC software.
Function 12h - Read current cursor location.
Input:
AH = 12h
Output:
DH = Row (line)
DL = Column
This function is exactly like INT 10h, sub-function 3, on the IBM
PC. The current cursor location (using the same coordinate system
as function 16h) is returned in DX.
This function should not be used by IBM PC software.
Function 13h - Single character ANSI write to screen.
Input:
AH = 13h
AL = Character to display
Output:
Nothing
The character passed in AL is sent displayed on the screen at the
current cursor location. ANSI.SYS type processing is performed.
This routine should not be used in such a way that DOS output
(which is not re-entrant) can not be employed by the FOSSIL to
execute the function.
ANSI.SYS is used by most FOSSIL drivers on the IBM PC.
This function should not be used on IBM PC software.
Function 14h - Enable or disable the DCD watchdog.
Input:
AH = 14h
AL = 01h - Enable watchdog
= 00h - Disable watchdog
DX = Port number
Output:
Nothing
This function enables and disables the monitoring of carrier
detect. When enabled, the state of the carrier detect (DCD) is
constantly monitored during timer tick processing. Should carrier
detect be lost (turned off), the system will be re-booted.
Activate/deactivate have no effect on the state of the DCD
watchdog.
This function is not supported by ONEFOSsil, and is dangerous in
many multitasking environments.
Function 15h - Write character to screen using BIOS.
Input:
AH = 15h
AL = Character to display
Output:
Nothing
The specified character is sent to the screen using BIOS-level
input/output routines. This differs from function 13h in that DOS
I/O will not be used.
This function should not be used by IBM PC software.
Function 16h - Add or delete a routine from the timer tick chain.
Input:
AH = 16h
AL = 01h - Add a function
= 00h - Delete a function
ES = Segment of function
DX = Offset of function
Output:
AX < 0FFFFh if operation is successful
= 0FFFFh if operation unsuccessful
This function is used to allow a central authority to manage the
timer interrupts, so that the integrity of the "timer tick chain"
is not compromised. Rather than using the traditional method of
saving the old contents of the timer vector, storing the address
of your routine there, and calling the "old" routine, instead you
call this function. The FOSSIL manages a list of such entry
points and calls them on a timer tick (interrupt) using a FAR
call.
X00 will allow up to 4 programs to hook into the timer tick.
Interrupts are enabled when the hooked routines are called.
CAUTION: When this FOSSIL function was implemented, it provided
the best means to hook into the timer tick on multitasking systems
at that time. However, with the 80386 and virtual 8086 mode of
operation used by DESQview, Windows V3.0+ etc., this function can
crash the system. The reason is the virtual 8086 application
(task/window) that hooked in, may not be the active virtual 8086
(task/window) when the timer tick interrupt occurs.
Due to popularity of the virtual 8086 type multi-tasking systems,
Ray Gwinn (who originally insisted that this function be created)
RECOMMENDS THAT THIS FUNCTION NOT BE USED.
ONEFOSsil returns 0FFFFh in AX at all times. Happy Ray?
Function 17h - Reboot system.
Input:
AH = 17h
AL = 00h - "Cold boot"
= 01h - "Warm boot"
Output:
Nothing
This function is intended primarily as a security feature. It
provides the application with a last resort escape from a
situation that could allow a security breach.
ONEFOSsil attempts to close the task that made the call, rather
than rebooting what could be a multi-user system.
This function should not be called by ANY software.
Function 18h - Block Read.
Input:
AH = 18h
CX = Requested number of characters to transfer
DX = Port number
ES = Segment of the caller's buffer
DI = Offset of the caller's buffer
Output:
AX = Number of characters actually transferred
This function will transfer from 0 to 65535 characters from the
inbound circular buffer to the caller's buffer. ES and DI are not
modified by this function. The number returned in AX will be the
lesser of the caller's requested amount or the entire contents (if
any) of the receive buffer.
I request that this function be used even for reading a single
character at a time. The following examples to help:
In ASM
push bp ;save frame pointer
mov bp,sp ;set it
xor ax,ax ;clear temp. value
push ax ;temporary storage
mov ah,18h ;function call 18h
mov cx,1 ;get 1 byte
mov dx,port ;port number
lea di,[bp-2] ;address of temp. storage
push ss
pop es ;move registers (size conscious)
int 14h ;make call
or ax,ax ;any data moved?
jnz @F ;data was moved
mov [bp-1],0FFh ;write AH to 0xFF
@@: pop ax ;if AH = 0, AL = character
pop bp
In C/C++
No real example available as I would use in-line ASM to
accomplish the function very similar to the above code.
Other people would use "regs" and "int86" calls.
Notice that you could detect if function 20h is available, and use
it when possible. FOSSILC, my C/C++ FOSSIL routines (freeware) do
exactly that.
This function should especially be used by file transfer protocol
software.
Function 19h - Block Write.
Input:
AH = 19h
CX = Requested number of characters to transfer
DX = Port number
ES = Segment of the caller's buffer
DI = Offset of the caller's buffer
Output:
AX = Number of characters actually transferred
This function will transfer from 0 to 65535 characters to the
outbound circular buffer. ES and DI are not modified by this
function. The number returned in AX will be the lesser of the
caller's requested amount or the amount (if any) required to fill
the transmit buffer.
This function should be used whenever possible!
Function 1Ah - Break begin or end.
Input:
AH = 1Ah
AL = 01h - Start sending 'break'
= 00h - Stop sending 'break'
DX = port number
Output:
Nothing
This function will start or terminate a break signal. This
function is useful for activating command mode on some modems.
The application program is responsible for the timing of the
BREAK. If ONEFOSsil has been restrained by an Xoff received from
the modem, the flag will be cleared. Any port setting functions
(including 04h and 1Ch) will stop an in progress break.
A break must be maintained long enough for the UART to have sent a
full data byte at the current settings. A break is a condition
where the serial line maintains the state of a start bit for a
full byte length.
Function 1Bh - Return information about X00.
Input:
AH = 1Bh
CX = Size of caller's info buffer in bytes
DX = Port number
ES = Segment of caller's info buffer
DI = Offset of caller's info buffer
Output:
AX = Number of bytes actually transferred
X00 returns the following:
CX = '0X' First 2 bytes of 'X00 ' string
DX = ' 0' Second 2 bytes of 'X00 ' string
ONEFOSsil returns the following:
BX = 'ON' No specific byte ordering, just the word
CX = 'E ' "ONE " if you were to look at it in a
register dump.
This function will transfer information about the selected port
and its status to the caller. This function is intended to assist
"generic" applications to adjust to the current environment.
Very little information should be used from the returned
information. An application should NOT use the buffer size or
buffer free information for anything. Use function 03h for
information about the buffers.
X00 returns the port status (function 03h) if this function is
called for an inactive port. BNU and ONEFOSsil return useful
information if they support the port.
X00 does not always return the following BAUD byte correctly.
ONEFOSsil contains extra fields in the following structure.
The data structure (assembly language style) currently returned by
ONEFOSsil is as follows:
INFO EQU $ ;DEFINE BEGIN OF STRUCTURE
STRSIZ DW INFO_SIZE ;SIZE OF THIS STRUC IN BYTES
MAJVER DB CURR_FOSSIL ;FOSSIL SPECIFICATION REV
MINVER DB CURR_REV ;REVISION OF THIS DRIVER.
IDENT DD ID_STRING ;"FAR" POINTER TO ASCIIZ
; DRIVER DESCRIPTION STRING.
IBUFR DW IBSIZE ;BYTE SIZE OF THE INPUT BUFFER
IFREE DW ? ;BYTES OF RECV BUFFER FREE
OBUFR DW OBSIZE ;BYTE SIZE OF THE XMIT BUFFER
OFREE DW ? ;BYTES OF XMIT BUFFER FREE
SWIDTH DB SCREEN_WIDTH ;WIDTH OF DISPLAY SCREEN
SHEIGHT DB SCREEN_HEIGHT ;HEIGHT OF DISPLAY SCREEN
BAUD DB ? ;BAUD RATE, COMPUTER TO MODEM
;the following are extensions
NEWBAUD DB ? ;new baud rate location
PORTSET DB ? ;complete port data settings
OVERRUN DW ? ;number overruns this session
The IDENT string is null-terminated, and does not contain a
new-line. The BAUD field contains the bits that Function 00h
would use to set the port speed and data format.
The fields related to a particular port (buffer size, space left
in the buffer, baud rate) will be undefined if the port is not
active.
In some cases X00 can not accurately return information. For
example, the user can lock the baud rate at 115200 when loading
X00. There is no correct FOSSIL value that X00 can return in the
BAUD field. X00 will set the BAUD field equal to the last baud
rate that the application attempted to set, at least that's what
X00REF.DOC says. It has been discovered that this is not true,
and that most the time, the BAUD field contains no usable data.
ONEFOSsil always sets the BAUD parameter to the closest possible
value. FHSLink really likes this practice, and as such displays a
baud rate without using the -B parameter. ONEFOSsil also uses the
NEWBAUD and PORTSET bytes. PORTSET is the bits function 1Eh would
write to the Line Control Register (minus the break bit). The
NEWBAUD byte contains a value similar to what function 1Eh would
use to set the baud rate. These are shown below.
Values of NEWBAUD:
00h = 110 27% error factor on 8250 series
01h = 150
02h = 300
03h = 600
04h = 1200
05h = 2400
06h = 4800
07h = 9600
08h = 19200
09h = 28800
0Ah = 38400
0Bh = 57600
0Ch = 76800 does not exist on 8250 series
0Dh = 115200
Values of PORTSET:
Bit 7 and 6 are always clear
Bit 3 is set if parity is enabled
Bits 5 - 4 define parity:
00 = Odd parity
01 = Even parity
10 = Mark parity (sticky odd)
11 = Space parity (sticky even)
Bit 2 defines the number of stop bits transmitted
0 = 1 stop bit sent
1 = 1.5 stop bits for 5 bit bytes, 2 for all others
Bits 1 - 0 define the number of data bits
00 = 5 data bits
01 = 6 data bits
10 = 7 data bits
11 = 8 data bits
The OVERRUN word is solely for information.
Extended Functions
Function numbers above 1Bh and below 7Eh are X00 extended functions.
These functions will only work with X00 and ONEFOSsil. It is fairly
easy to see if other FOSSIL's support X00 functions by checking the
maximum function supported on the "Activate" call.
It is the hope of Ray Gwinn that these functions will be added by other
FOSSIL authors in their implementations and become a part of the FOSSIL
specification. I would personally like to see a whole new, non UART
specific specification emerge. This new specification would get rid of
the inefficiency FOSSIL 5 permits and clear up some of the compatibility
issues with the new BIOS's.
Functions 1Ch and 1Dh are exact duplicates of FOSSIL functions 04h and
05h. Functions 1Eh and 1Fh are intended to be exact duplicates of
functions 04h and 05h of the PS/2's BIOS INT 14h. Function 20h is a
destructive read with no wait. Function 21h is a Stuff/Poke character
into the receive buffer. Note that function 1Eh or 1Fh are not exactly
compatible with functions 04h and 05h of the PS/2 BIOS.
Developers are encouraged start using functions 1Ch and 1Dh instead of
functions 04h and 05h. See the application notes section for
instructions on a compatible method of determining if functions 1Ch and
1Dh should be used instead of functions 04h and 05h.
Function 1Ch - Activate Port.
This function is identical to function 04h. Please refer to
function 04h for information.
Function 1Dh - Deactivate Port.
This function is identical to function 05h. Please refer to
function 05h for information.
Function 1Eh - Extended line control initialization.
This function is intended to exactly emulate the PS/2's BIOS INT
14 services, function 04h. Some or all of the functions provided
here are duplicated by other FOSSIL functions. In addition, once
this function is called, function 00h will not be allowed to
change the baud rate. Function 00h will again be allowed to set
the baud rate after the FOSSIL functions have been deactivated.
Input:
AH = 1Eh
AL = Break, Where:
= 00h, No break and/or turn off break
= 01h, Start send of break.
BH = Parity, where:
= 00h, No parity
= 01h, Odd parity
= 02h, Even parity
= 03h, Mark parity (always 1)
= 04h, Space parity (always 0)
BL = Stop bits, where:
= 00h, One bit
= 01h, 1.5 bits on 5 bit bytes, 2 stop bits for all others
CH = Word length, where:
= 00h, 5 bits
= 01h, 6 bits
= 02h, 7 bits
= 03h, 8 bits
CL = Baud rate, where:
= 00h, 110 baud
= 01h, 150 baud
= 02h, 300 baud
= 03h, 600 baud
= 04h, 1200 baud
= 05h, 2400 baud
= 06h, 4800 baud
= 07h, 9600 baud
= 08h, 19200 baud
= 80h, 28800 baud (these are FOSSIL only baud rates)
= 81h, 38400 baud
= 82h, 57600 baud
= 83h, reserved (future 76800 baud)
= 84h, 115200 baud
DX = Port number
Output:
AX = Port status (see function 03h)
If settings were locked at load time, the appropriate parameters
are ignored.
ONEFOSsil does not permit the break bit to be set by this
function. The value in AL is ignored. The reason is that the
PS/2 specification calls for a value of 0 to make a break and a 1
to clear a break. X00REF.DOC states the function as it appear
above, but the Interrupt shows it as being an exact duplicate of
the PS/2 function. I do not wish to trouble myself with programs
that fail to work because their authors used the Interrupt List to
write them.
Function 1Fh - Extended serial port status/control.
This function is intended to exactly emulate the PS/2's BIOS INT
14 services, function 05h. Some or all of the functions provided
here are duplicated by other FOSSIL functions. This function has
2 sub-functions specified by AL.
Sub-function 00h - Read MCR
Input:
AH = 1Fh
AL = 00h, Read modem control register (MCR)
DX = Port number
Output:
AX = Port status (see function 03h)
BL = Modem control register, where:
Bits 7-5 = 0 (Reserved) (always 0)
Bit 4 = 1 Loopback mode
Bit 3 = 1 OUT2 (interrupts) enabled
Bit 2 = 1 OUT1 active
Bit 1 = 1 Request to send (RTS) active
Bit 0 = 1 Data terminal ready (DTR) active
Sub-function 01h - Write MCR
Input:
AH = 1Fh
AL = 01h, Write modem control register (MCR)
BL = Modem control register, where:
Bits 7-5 = 0 (Reserved) (forced 0)
Bit 4 = 1 Set loopback mode
Bit 3 = 1 Set OUT2 enable interrupts (forced 1)
Bit 2 = 1 Set OUT1 active (on)
Bit 1 = 1 Set Request to send active (on)
Bit 0 = 1 Set DTR active (on)
DX = Port number
Output:
AX = Port status (see function 03h)
In sub-function 01h (write MCR) X00 will force bit 3 to 1. That
is, X00 will not allow the communications interrupts to be
disabled.
RTS may be used as a flow control signal by the FOSSIL. When the
application program writes the MCR, the RTS bit is treated as an
RTS enable bit. This means that X00 will allow the application
program to signal when it wants to allow RTS on. It does not
force RTS on.
ONEFOSsil only permits the DTR to be modified with this function.
This function should not be used for any reason. It is hardware
specific and such hardware may not exist in the future.
Function 20h - Read with no wait (destructive).
Input:
AH = 20h
DX = Port number
Output:
AH = 00h if a character is available
> 00h if no character is available
AL = Next character if available
This function returns the next character from the receive buffer.
This function is the same as function 0Ch except that any
character returned is removed from the receive buffer.
Function 21h - Stuff/Poke the receive buffer.
Input:
AH = 20h
AL = Character to place in the receive buffer
DX = Port number
Output:
Nothing
This function will insert the passed character into the receive
buffer (at the end). Subsequent reading of the serial input will
read the character. The character is inserted at the end of the
buffer (as though it were just received.)
The character is inserted into the receive buffer by calling the
receive interrupt routine. All normal receive checking is
preformed on the character. Some things to note are:
If receiving of Xon/Xoff is enabled and an Xoff is stuffed/poked
into the buffer, the transmitter will stop until a an Xon is
received or stuffed/poked.
If Control-C/K checking is enabled and a Control-C/K is
stuffed/poked, then the character is not put in the buffer and the
internal flag is set.
ONEFOSsil does not support this function as there is no known need
for it.
"Layered Application" services
ONEFOSsil supports NO "Layered Application" services. The functions
simply aren't monitored. I don't feel most people have any use for
them.
Application Notes
Which Activate/Deactivate functions to use
It is the hope of Ray Gwinn (after a period of time) to make X00's
functions 04h and 05h compatible with the PS/2's INT 14h functions 04h
and 05h. Currently, X00's functions 04h and 05h are duplicated at
functions 1Ch and 1Dh respectively. Ray requests that application
programmers start using functions 1Ch and 1Dh if those functions are
available. That is, use functions 1Ch and 1Dh instead of functions 04h
and 05h respectively.
It is relatively simple to determine if the functions at 1Ch and 1Dh are
available. When your program is ready to activate the FOSSIL for a
given port, issue function 1Ch. If 1954h is returned, then the port is
activated. If 1954h is not returned, reissue the request to function
04h. Save the function number actually used to activate the port, then
increment it by one to deactivate the port. You may also keep track of
the maximum function supported by the driver, to see what other calls
are available. You should; however, leave a user configured option to
override all extended function calls.
<EoF>