BAUD bps or

BAUD [port,] bps(SMS and ST/QL only)

Location QL ROM

The serial port(s) use a certain speed to communicate with printers, modems, other computers, interfaces etc. This speed is set with BAUD. The only values allowed are set out below, any other value for bps will produce an error. The unit of the parameter is bits per second.

BAUD will set the same output and input baud rate for both serial ports.

Bits/Sec Bytes/Sec Time/32Kb
75 9.375 58 min, 15 sec
300 37.5 14 min, 34 sec
600 75 7 min, 17 sec
1200 150 3 min, 38 sec
2400 300 1 min, 49 sec
4800 600 55 sec
9600 1200 27 sec
19200 2400 14 sec


The effect of BAUD 19200 depends on the hardware. On standard QLs the serial port can only send data at that baud rate and tends to be affected by the QL’s sound chip.


On a standard QL without Minerva the actual baudrate is slightly lower than that stated above.


In practice, data is compressed and transmitted with transfer protocols (to reduce transmission errors), so the above transmission times refer to the actual speed of the hardware, not the amount of data.


The standard QL cannot safely handle the input of data at baud rates greater than 1200.


A modified co-processor Hermes which replaces the 8049 chip by a 8749 is available, which allows independent input baud rates and (if Minerva v1.95+ is present) independent output baud rates as well as fixing all mentioned problems for QLs and AURORA boards. The more expensive version of Hermes (SuperHermes) also provides three additional low speed RS232 input ports (supporting 30 to 1200 bps) and a high speed RS232 two way serial port (supporting up to 57,600 bps, which equates to 4800 characters per second).


On a QXL board without SMS v2.57+, a BAUD command would not have immediate effect if a serial channel was open - it waited until you closed the channel.


It is possible to connect a mouse to a QL through the standard serial port. Although the mouse operates at 1200 baud, you can use the mouse alongside a printer (or modem) either with the assistance of Hermes or by configuring the mouse software to de-activate whilst the higher baud rate is in use.


The THOR XVI allows the following additional baud rates:

Bits/Sec Bytes/Sec Time/32Kb
110 13.75 39 min, 43 sec
134.5 16.8125 32 min, 29 sec
150 18.75 29 min, 08 sec
1800 225 2 min, 26 sec

Independent baud rates may also be used on output and input channels when the channel is opened by using an extended device name.


Minerva v1.93+ now enables you to set different output baudrates for ser1 and ser2 - if you want different input baudrates for the two ports, you will need Hermes (see above). Unfortunately, this enhancement will only work on QLs without Hermes if both ports are output only.

If you want to disable the ability to handle different output baud rates, do so with the command: POKE !124 !49,2

In order to set the two baudrates independently, BAUD will now accept additional values in the range -1 to -128. This is calculated by looking at the following table, working out which features you will need and adding the values accordingly to -128:

Value to Add Effect
64 Alters ser2 baudrate (ser1 is default)
16 Prevents standard BAUD command from altering baudrate on this port
7 Selects BAUD 75 on this port
6 Selects BAUD 300 on this port
5 Selects BAUD 600 on this port
4 Selects BAUD 1200 on this port
3 Selects BAUD 2400 on this port
2 Selects BAUD 4800 on this port
1 Selects BAUD 9600 on this port
0 Selects BAUD 19200 on this port

Please only try to add one baud rate value!!

Minerva Examples

BAUD -128

sets the baud rate for ser1 output at 19200. ser2 is unaffected.

BAUD -47

fixes the baud rate for ser2 output at 9600. ser1 is unaffected (-47 = -128+64+16+1).


If BAUD is only followed by one parameter, then it sets the baud rates for both SER1 and SER2 on the QL, AURORA and QXL boards. However, if SMSQ/E is running on an ATARI computer, or the command is used on an ST/QL Emulator then it only sets the baud rate on SER1.

You can however supply two parameters to the command to set independent baud rates (note that on a standard QL or Aurora, Hermes is needed for independent baud rates on each serial port). In this case, the first parameter is the number of the serial port to be set and the second number is the new baud rate, for example:

BAUD 1,19200

sets the baud rate on SER1 to 19200 - any other serial ports are left unaffected. If the rate (bps) is specified as zero, this selects the highest possible BAUD rate on that port.

Please also note that if a translate has been set up with the TRA command, changing the BAUD rate will make that translate apply to all channels opened to the serial ports, whether or not they are already open. See TRA for more details.

The following additional BAUD rates are also supported on the specified SMSQ/E version:


  • 1275(1200 receive and 75 transmit - only works with HERMES)
  • 75(75 receive and 1200 transmit - only works with HERMES)

(The standard 1200 and 75 Baud rates are not supported)


On these computers, the different serial ports support different baud rates. An ST/STE only has one serial port (SER1), a Mega STE has three (SER1, SER2 and SER4), and a TT has four (SER1, SER2, SER3 and SER4).

Support for SER2, SER3 and SER4 was only added to the ST/QL Emulators in version E-37 of the Drivers. It has always existed in SMSQ/E.


  • supports all the standard baud rates from 300 to 19200, except 7200.


  • supports all the standard baud rates from 300 to 19200 (including 7200) as well as 38,400, 76,800, 83,333 and 125,000 baud (1x and 2x MIDI speeds).
    • If the rate specified is 0, the rate used is 153,600.
  • Note that 38,400 on the TT was implemented in v2.69. 38,400, 76,800, 83,333, 125,000 and 153,600 BAUD were implemented for the STE and TT in v2.73.


  • supports the same rates as SER1.
  • Hardware handshaking is not available on this port.


  • supports all the standard baud rates from 300 to 38,400 plus 57,600.
  • If the rate specified is 0, the rate used is 230,000.


All of the standard baud rates available to the normal QL are supported except for 75 Baud.


All of the same baud rates as the QXL implementation are supported plus 38,400 and 57,600 baud.


If one of the PC’s serial ports is already linked to a mouse (in DOS) then the BAUD command will not affect that port.


The Devices Appendix supplies details about the serial device ser and parallel device par. The ser_… and par_… commands allow you to set various other parameters for serial and parallel ports.

You can check the current baud rate setting with BAUDRATE.