Technical information

Serial Solutions Aterm
clsp01:
ret ;Done
close_com endp
DOS function 03EH does not access the device driver, but
merely informs DOS that the program no longer wishes to use
the file.
Serial Port Parameters._____________________
The serial port settings, the Baud rate, parity etc., must be
set to the values that the remote device requires. In ATERM this
is all done by one subroutine, bios_x_init.
Figure 8-6. Subroutine Bios_x_init.______________________________
;********************************************************************
;* *
;* bios_x_init-check the global parameters for baud rate etc. *
;* if they are ok then use to set the current serial port *
;* return carry set if fails. *
;* *
;********************************************************************
; On entry
; Segment registers as start proc
; Globals comno,baud,parity,stopbits,startbits set with values
;
; On exit
;
; Carry = true ==> values bad, could not set port
; AH,BX,CX,DX undefined
; Carry = false ==> values good, used to set port.
; AX,BX,CX,DX as BIOS service 04H
; Other flags undefined
; All other regs maintained.
; Stack useage-as BIOS service (currently 22 bytes)
;
; Note- this service assumes the presence of Brain Boxes Asynchronous
; BIOS. This is included in the Brain Boxes serial device driver.
;
bios_x_init proc near
mov al,brk
cmp al,1
ja bxi01 ;Bad break parameter
mov bh,parity
cmp bh,4
ja bxi01 ;Bad parity
mov bl,stopbits
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