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Document	V1I9A15
Title	VERBatim - V124
Keywords	V124 V122 V123 SERIAL V124.TXT UTILITY.DOC PORT FLUSH
Text	This is the assembler routine used for addressing the serial port It is the routine called by both V122 abd V123 and can thus be used to replace both of them The same caveat regarding device drivers applies V124 has been documented by Dan Ellis on the RevTech bulletin board (1985) by RevTech in the "System Subroutines" documentation available to Advantage subscribers and in V124 TXT in UTILITY DOC Unfortunatley documentation is in part conflicting and/or misleading so we present below details of CALLING V124 As V124 is an assembler routine it is passed varying numbers of parameters depending upon the action to be taken but the basic parameters are V124( Action Channel Info Amt Status ) where ACTION is the action to take CHANNEL is the handle assigned by DOS to the device driver INFO is the data being sent to/from the driver/buffer AMT is used to state the number of bytes to read FROM the driver/buffer and STATUS is a flag variable To utilise the serial port the device must first be opened (OP) and if necessary configured (CI/CO) Information can then be either read (RD) or written (WR) WITH the Break Key being checked for (TB) until all operations are completed at which stage the device must be closed (CL) Please note that before opening the device for the first time an RBASIC FLUSH should be issued to ensure integrity of string space/data OP V124("OP" CHANNEL "COMM$" : CHAR(0) "" FLAG) Note that INFO is here set to the DOS internal name for the port This action opens the port to the channel and returns a FLAG of 0 for OK 1 for fail CI V124("CI" CHANNEL INFOR 7 FLAG) Returns a seven byte string in INFO containing the CURRENT port parameters When a number is represented by a byte the ASCII character is returned not the literal EG Char(2) not 2 Byte 1 the baud rate Returns a number between 0 and 15 this representing a baud rate of 50 75 110 134 5 150 200 300 600 1200 1800 2000 2400 3600 4800 9600 or 19200 EG 0 = 50 14 = 9600 etc Byte 2 number of stop bits Byte 3 number of data bits Byte 4 literal character for parity Byte 5 Protocol byte If this Byte is CHAR(4) XOFF mode is set if CHAR(16) STRIP nulls mode is set if CHAR(20) both modes are set Byte 6 not used Byte 7 break count CO V124("CO" CHANNEL INFO) Used to set the CURRENT port parameters INFO should be loaded WITH a seven byte string WITH LAYOUT as above When a number is represented by a byte the ASCII character should be used not the literal EG CHAR(2) not 2 Note that Byte 6 should be loaded WITH a CHAR(0) RD V124("RD" CHANNEL INFO) The IO equivalent of an INPUT INFO 1 Returns whatever is waiting in the buffer at the time the request was issued and waits for no special characters to return WR V124("WR" CHANNEL INFO) The IO equivalent of a PRINT : Places the INFO into the BUFFER for sending along the serial LINE TB V124("TB" INFO) Sees if break key has been hit and if so sends a break signal to the port CL V124("CL" CHANNEL) Closes the channel to the port/device driver This MUST be DONE at the end of a comms SESSION otherwise data corruption could occur For examples of USING the above COMMANDS see V124 TXT on UTILITY DOC (Volume 1 Issue 9 Pages 7 8)

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