APPENDIX B
Common PEN*KEY 6000 Series Information
B-28 PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide
BIOS
In its simplest form, the basic input/output system (BIOS) is composed of softĆ
ware that allows the operating system (in this case, DOS) to interact with the
PC hardware. The BIOS may also be known as firmware" or system software.
The BIOS, in most desktop PCs, is typically contained on ROM chips. In the
PEN*KEY 6000 Series Computer, the BIOS is programmed into flash memory to
allow you to periodically update the system, without physically opening the unit
to replace any of the chips.
Applications
DLLs
INIs
APIs
Additional
Windows
Files
(optional)
Handwriting
Recognition
Pen Windows
Minimal Windows System Files
Windows Drivers
DOS
DOS Drivers
BIOS
Hardware
The BIOS manages the system through the use of interrupts, which are basically
signals generated by the hardware to indicate that they need the attention of the
CPU. For example, when you type characters at the keyboard, your key presses
are changed into binary strings and sent to the BIOS. When the BIOS receives
the string, it sets an interrupt to alert the CPU that it has data to be processed.
All of this happens in just a fraction of a second.
From the software's point of view, BIOS is sometimes referred to as a Hardware
Abstraction Layer (HAL). HAL is an important concept, in view of the fact that,
an application that is written for a computer with HAL can be easily moved to
another computer where the hardware is different. For those peripherals that
are supported directly by BIOS, software developers need not be concerned about
differences between hardware from various manufacturers. Hard drives are one
example, since all these devices look the same
upstream
of BIOS. Between BIOS
and the hardware, using the hardware device is often a matter of setting paramĆ
eters for BIOS. This is commonly the case with hard drives, where the user
must first set parameters in BIOS before the hard drive can be seen" by DOS.
Hardware that is not directly supported by BIOS, such as a PC Card drive, must
be supported by a BIOS extension (known as a DOS
device driver
).
B. Common PEN*KEY
6000 Series Info.
