OS_Si, Low level serial interface
- Gunther Strube
- Elpekos
Register parameters
IN:
L = reason code
Other register parameters depend on reason code
OUT:
Depends on reason code, see below.
IX will always be unchanged.Â
Notes
SI_HRD
IN: -
OUT: Fc = 0
Registers changed after return:
..BCDEHL/IXIY same
AF....../.... different
This resets the UART in the gate array. This call should not need to be used.
SI_SFT
IN: -
OUT: -
Registers changed after return:
......../IXIY same
AFBCDEHL/.... different
This call should be useful to install new panel settings or when starting low level (ie. using SI_GBT, SI_PBT etc.) serial operations. It carries out the following:Â
1. Empty receive and transmit buffers.
2. Reset the XON/XOFF flags.
3. Reset baud rates, parity and flow control settings to the PANEL values.
4. Assert RTS.
5. Resets the serial port timeout to its default of 10 minutes.Â
SI_INT
IN: -
OUT: -
Registers changed after return:
AFBCDEHL/IXIY same
......../.... different
Internal operating system usage only.
This call is used by the serial port driver to send XOFF when software handshaking is active.Â
SI_GBT
IN: BC = timeout in centiseconds
Out if call succeeded:
Fc = 0
A = byte received
BC = remaining time
Out if call failed:
Fc = 1
A = RC_TIME ($02) (if no data available before timeout)
Registers changed after return:
....DE../IXIY same
AFBC..HL/.... different
SI_PBT
IN: BC = timeout in centiseconds. If BC = $FFFF then default timeout.
A = byte to send
Out if call succeeded:
Fc = 0
BC = remaining time
Out if call failed:
Fc = 1
A = RC_TIME ($02)
Registers changed after return:
....DE../IXIY same
AFBC..HL/.... different
This call will return immediatly if there is space in the transmit buffer, otherwise it will wait until there is space for as long as the timeout. If the timeout is exceeded it will return with an error.
SI_ENQ
IN: -
OUT:
B = number of full slots in the Tx (transmit) buffer
C = number of empty slots in the Tx (transmit) buffer
D = number of full slots in the Rx (receive) buffer
E = number of empty slots in the Rx (receive) buffer
A0 = 1, CTS level (inverse of the value on the D-connector)
A1 = 1, DCD level (inverse of the value on the D-connector)
A2 = 1, Rx register full
A3 = undefined
A4 = 1, Tx Register empty
A5 = 1, CTS interrupt
A6 = 1, DCD interrupt
A7 = 1, Rx shift register full
Registers changed after return:
......../IXIY same
AFBCDEHL/.... different
A slot, in this context, is the set of bits required to transmit on character. This will include 8 data bits plus start and stop bits.
SI_FTX
IN: -
OUT: Fc = 0
Registers changed after return:
A.BCDEHL/IXIY same
.F....../.... different
SI_FRX
IN: -
OUT: Fc = 0
Registers changed after return:
A.BCDEHL/IXIY same
.F....../.... different
SI_TMO
IN: BC = new value for default timeout
OUT: Fc = 0
Registers changed after return:
A.BCDEHL/IXIY same
.F....../.... different
If you set the default to $FFFF then when the default is used (by setting a timeout value of $FFFF in get and put byte routines) then the system will wait forever. A soft reset sets the default timeout to 10 minutes. This timeout is completely independent of the system timeout, which is set by the Panel.
SI_GX
IN:
BC = number of byte to get from serial port, maximum 16384, one bank
DE = destination
DE = 0, write bytes to a file opened with its handle in IX
DE > 0, write bytes to memory at (DE)
IX = file handle (if DE = 0)
Out if call succeeded:
Fc = 0
BC = remaining time (SI_TMO)
DE = points at last byte fetched + 1 (if DE(IN) > 0)
Out if call failed:
Fc = 1
A = RC_TIME, timeout elapsed
A = RC_EOF, end of file reached
A = RC_WP, input device is read protected
BC = number of bytes not read
Registers changed after return:
......../IXIY same
AFBCDEHL/.... different
SI_PX
IN:
BC = number of byte to write to serial port, maximum 16384, one bank
DE = input
DE = 0, input is a file/device opened with its handle in IX
DE > 0, input is memory at (DE)
IX = file handle (if DE = 0)
Out if call succeeded:
Fc = 0
BC = remaining time (SI_TMO)
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Out if call failed:
Fc = 1
A = RC_TIME, timeout elapsed
A = RC_EOF, end of file reached
A = RC_RP, input device is read protected
BC = number of bytes not written
Registers changed after return:
......../IXIY same
AFBCDEHL/.... different
SI_GXT
IN:
BC = number of byte to get from serial port, maximum 16384, one bank
DE = destination
DE = 0, write bytes to a file opened with its handle in IX
DE > 0, write bytes to memory at (DE)
IX = file handle (if DE = 0)
Out if call succeeded, Fc = 0:
Fz = 1,
BC <> 0, A = ESC terminator encountered, number of bytes not read
Fz = 0,
A = FFh
BC = 0, all bytes read, no terminator encountered
DE = points at last byte fetched + 1 (if DE(in) > 0)
Out if call failed:
Fc = 1
A = RC_TIME, timeout elapsed
A = RC_EOF, end of file reached
A = RC_WP, input device is read protected
BC = number of bytes not read
Registers changed after return:
......../IXIY same
AFBCDEHL/.... different
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