Vidicode Argus Basic Programmers Reference Manual

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
38
  
BRK    transmit a break 
BRK is used to make the modem transmit a break on the specified port.  When no port is specified OPORT is used.  The 
duration of the break can be controlled with S-register 43, but the default value of 0.50 seconds is usually sufficient. See ON
BRK also. 
Examples: 
BRK#3
ON HANGUP BRK#1
Syntax: 
BRK (#[port])
See also: 
ON BRK 
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
39
  
BUFFER    reserve buffer space 
As a result of the fact that the various components of a communications system operate at different speeds, it is often 
necessary to store data temporarily in an area of memory called a buffer.  The advantage of this is that one device can take 
data out of the buffer while another puts new data in.  If the buffer is sufficiently large, the faster of the two devices will not 
have to wait for the other.  For instance with a computer, when you read a character from a file on disk, a whole block of data 
from the file - perhaps 512 bytes - is read into an area of memory called a file buffer.  When you read the next character the 
processor does not have to wait for the disk drive again, because the data is already in the file buffer. 
 
The BUFFER command on the modem is used to create a buffer of the specified size in RAM.  This buffer is treated as if it 
were a serial port and is addressed as port number 8.  The amount of memory that can be allocated for the buffer is limited 
by the available memory, but the last location, or top of the buffer, is always &7FFF.  Note that this is also where program 
variables are stored, so that if you intend to use the BUFFER command you must do so before you declare any variables. 
 
When the BUFFER command is used, an automatic check will make sure that a program is not overwritten.  If there is 
insufficient room for a buffer of the specified size, an error message will be given. 
 
The command: 
BUFFER &400
will reserve 1K of RAM for the buffer.  The maximum buffer size is 20K. 
 
The PUT and PRINT commands are used to store data into the buffer: 
PRINT#8,text
PUT#8,Ch
To retrieve data from the buffer use the GET, KEY or INPUT commands. 
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
40
  
In the following example the next byte of data is read from the buffer and placed in the variable X: 
X=GET#8
It is  acceptable to use PUT#8, INPUT#8, GET#8, etc., to manipulate the buffer contents; but when frequent buffer 
access is required, it is more efficient to use IPORT and OPORT to select port 8 as the default port.  The port number can 
then be omitted from the I/O commands. 
 
The buffer can also be used in conjunction with the LINK command as if it were a normal port.  For example: 
LINK#1,#8
LINK#8,#2
Here, the input from port 1 will be placed in the buffer before being extracted and passed to port 2.  This is particularly useful 
if you are speed-buffering between ports.  When using the buffer in this way it is not possible to implement handshaking 
between the ports, so that if port 1 is very much faster than port 2 the buffer may overflow, and characters will be lost. 
 
The CLEAR#8 or CLEAR BUFFER command is used to empty the buffer by resetting the input and output buffer pointers 
to the buffer start address.  With a 1K buffer this will be &8000 - &400 = &7C00.  Any data still in the buffer when 
the CLEAR command is used will be lost.  However with the command RESTORE BUFFER all the data can be read 
again. 
 
The BUFFER OFF command releases the space allocated for the buffer for other use.  The command CLEAR is then 
executed automatically, so be careful here. 
 
The buffer contents are not affected by the STOP or RESET buttons. 
 
If no buffer space has been allocated, an attempt to access port 8 will not generate an error message, but will cause the 
program to hang. 
 
For more complex operations on the buffer, the programmer can use PEEK and POKE on the following buffer-related 
addresses: 
 
256*PEEK&4A4+PEEK&4A5 = buffer start address
256*PEEK&4A6+PEEK&4A7 = buffer end address
256*PEEK&4A8+PEEK&4A9 = buffer start pointer
256*PEEK&4AA+PEEK&4AB = buffer ebd pointer
PEEK&43 AND &80 = buffer full flag
PEEK&44 AND &80 = buffer empty flag
 
Important: 
 
When a modem connection is made and MNP5 is active, a buffer of 3K (&C00) must be defined.  This space is used by 
MNP5 and must not be overwritten during the connection. 
 
When using file transfer with the 1-K block option (Ymodem, Xmodem-1K) together with MNP5, then a buffer of at least 4K 
(&1000) must be defined. 
Examples: 
BUFFER 1000
BUFFER Size
BUFFER OFF
Syntax: 
BUFFER [num] 
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
41
  
BUFFER OFF
See also: 
IPORT, OPORT, LINK, RESTORE BUFFER
 
 
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
42
  
BUTTON    read the S/A button position 
BUTTON is used to read the position of the sync/async button from within your program.  When the button is in the in 
position, the function will return 1; and when the button is in the out position, the function will return 0. 
Examples: 
IF BUTTON THEN GOSUB Syn_Com
PRINT BUTTON
Syntax: 
[num-var] = BUTTON
See also: 
ON BUTTON
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
43
  
CALL    jump to machine code subroutine 
The CALL command is used to execute a machine language subroutine.  Such routines are normally only used where high 
speed operations are required for which BASIC would be too slow.  (Which is not very often, because Argus BASIC is fast!) 
 
Each CALL command must be followed by the start address of the routine: 
CALL &4000
In addition to the call address, parameters can be passed to the routine in the 16-bit accumulator and in the 16-bit X and Y 
registers. 
CALL &4000, A, X, Y
where the variables A, X and Y have been set to the appropriate values before calling. 
CALL &4000,1294,7,128
Here, the accumulator is set to 1294, the X register to 7 and the Y register to 128. 
 
The last instruction of the machine code routine must be RTS in order that control is passed back to the BASIC program.  On 
return, the contents of the accumulator and the X and Y registers are stored in locations &2E00, &2E02 and &2E04 and can 
be accessed using the PEEK function. 
 
When more than three bytes of data must be passed to a machine code routine, the POKE command should be used to 
place the data in memory at a convenient location.  The safest method is to reserve an area of memory with the DIM 
command, e.g.: 
DIM Block 200
As the modem does not include a built-in assembler, development of machine code routines must be carried out on another 
computer.  The assembled code may then be uploaded into the modem using the appropriate form of the RECEIVE 
command. 
Examples: 
CALL &3000
CALL Measure,2,X,Y
CALL Calculate,G1,G2
Syntax: 
CALL [address] ( , [Accu], [X-reg], [Y-reg] )
See also: 
PEEK, POKE, RECEIVE
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
44
  
CHR$    character string 
The CHR$ function converts an integer in the range 0-255 to its equivalent ASCII character.  It is commonly used to include 
control characters (ASCII values from 0-31) in PRINT commands.  For example, to sound a warning at the terminal when 
an error occurs, the Bell character ASCII 07 (entered at the keyboard as [Ctrl-G]), could be incorporated into the error 
message as follows: 
500 E$=Error !+CHR$7
510 PRINT E$
Examples: 
X$=CHR$(48+X)
PRINT CHR$75
Syntax: 
[string-var] = CHR$ [integer 0..255]
See also: 
ASC
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
45
  
CLEAR    clear variables/memory 
CLEAR can be used in one of nine ways: 
1. CLEAR 
When used on its own, it will clear all BASIC program variables. 
2. CLEAR ALL 
Will clear the input and output buffers of all ports. 
3. CLEAR (#[port]) 
When followed by one or more port numbers, it will clear the input and output buffers for those ports. 
4. CLEAR INPUT (#[port]) 
CLEAR followed by INPUT empties the input buffer for the specified port.  If no port is specified, the default input port as 
defined by IPORT will be assumed. 
5. CLEAR OUTPUT (#[port]) 
CLEAR followed by OUTPUT empties the output buffer for the specified port.  If no port is specified, the default output port 
as defined by OPORT will be assumed. 
6. CLEAR BUFFER 
This will empty the buffer you have defined, but not disable the buffer.  This function will do the same as CLEAR#8 but 
takes less program space. 
7. CLEAR PRINTER 
This will clear the printer port.  CLEAR#7 will also clear the printer port. 
8. CLEAR! or CLEAR FILE 
This deletes all files from the RAM/FLASH-disk and should therefore be used with care!  If you accidentally type in this 
command, you should use RESTORE! immediately to recover the RAM-disk contents. Recovering the FLASH-disk is not 
possible. 
9. CLEAR ROM 
Is used when a RAM-disk is in socket 2 to clear the chip. 
Examples: 
CLEAR
CLEAR ALL
CLEAR OUTPUT
CLEAR INPUT#1,#3
CLEAR PORT 1 
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
46
  
CLEAR BUFFER
CLEAR FILE
CLEAR !
Syntax: 
CLEAR
CLEAR ALL
CLEAR#[port](,...)
CLEAR INPUT ( #[port])(,...)
CLEAR OUTPUT ( #[port])(,...)
CLEAR BUFFER
CLEAR PRINTER
CLEAR (!/FILE)
CLEAR ROM
See also: 
RESTORE, RESTORE ROM, ROM
  
						

							ARGUS Programmable Modem 
BASIC Programmers Reference Manual 
© 1990 - 1997 Vidicode Datacommunicatie BV 
47
  
CLOCK$    read internal clock 
CLOCK$ is used to read the time and date from the internal real-time clock.  Output is given in the format: 
DAY dd-mm-yy
HH:MM:SS
DAY is day of the week (e.g. SUN); dd is the day of the month, mm is the month, yy is the year, HH is the hour, MM is the 
minute and SS is the second. 
 
CLOCK$ can be used to set the date and time, but this can usually be done more easily using the individual DAY, DDAY, 
MONTH, YEAR, HOUR, MIN and SEC commands. 
 
CLOCK$ can be copied into another string to store the time and date of a certain event permanently. 
Examples: 
C$=CLOCK$
CLOCK$
Syntax: 
[string-var] = CLOCK$
See also: 
DDAY, DAY, MONTH, YEAR, HOUR, MIN, SEC,
DATE$, TIME$