XBIOS Device and System Functions
Handshake
Values
0
1
2
Handshake Method
No handshaking
XON/XOFF
RTS/CTS (not implemented in preblitter ROMs)
Note that a setting of 3 turns on both XON/XOFF and
RTS/CTS, which is meaningless. Also note that in the first
(preblitter) TOS ROMs, the RTS/CTS handshake method was
not supported.
The other input parameters for the Rsconf() function,
ucr, rsr, trs, and scr are used to set various 8-bit registers on
the 68901 Multi-Function Peripheral interface chip (MFP).
The first, ucr, sets the USART (Universal Synchronous/Asyn
chronous Receiver/Transmitter) control register. This controls
various communications parameters such as parity, stop bits,
and data bits per word. The function of each of the register
bits are as follows:
Table 3-2. ucr Bits
Bit Function
0 Not used
1 Parity type
0 = Odd
1 = Even
2 Parity enable
0 = Off
2 = On
3-4 Async start and stop bits
Bit value
4 3 Number of Start and Stop Bits
0 0 No start or stop bits (synchronous)
0 1 One start bit, one stop bit
1 0 One start bit, V/2 stop bits
1 1 One start bit, two stop bits
5-6 Data bits per word
Bit value
6 5 Number of Data Bits
0 0 Eight bits
0 1 Seven bits
1 0 Six bits
1 1 Five bits
35
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