Toshiba laptop the pair of ports E4h and E5h can be used to get and set many of the features of the laptop. For the most part thought it is better to use the System Configuration Interface and Hardware Configuration Interface where possible. The two ports work in a similar manner to the CMOS RAM ports 70h and 71h. First Toshiba write to port E4h which of the chipsets registers we wish to manipulate. Then Toshiba read or write as appropriate to port E5h to get or set the register. All the Toshiba code that manipulates these ports slows down the I/O with short jumps, however this does not appear to be necessary. It is however essential that interrupts are disabled while reading and writing to ports 0xE4 and 0xE5. Failure to do so could lead to a system crash if two or more programs attempt access to these ports at the same time. Toshiba laptops have a unique identification number held in the BIOS that can be used to identify the model on which a program is running. There are two different methods by which this number can be retrieved.
The first method is the simplest and is the method reqired on all older models. For this method the identification number is stored in two bytes of the BIOS memory area.
The Second method is for newer models (including all current ones) a different method is required. This method is called the SCT Table method by Toshiba. This method of retrieving the
machine identification number needs to be user when the original method returns a value of 0xFC2F.
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