Page 195 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes
9.1.11.1 Embedded Programs
Some computer programs are embedded into hardware. A stored-program computer requires an
initial computer program stored in its read-only memory to boot. The boot process is to identify
and initialize all aspects of the system, from processor registers to device controllers to memory
contents. Following the initialization process, this initial computer program loads the operating
system and sets the program counter to begin normal operations. Independent of the host
computer, a hardware device might have embedded firmware to control its operation. Firmware
is used when the computer program is rarely or never expected to change, or when the program
must not be lost when the power is off.

Figure 9.4: The Microcontroller on the Right of this USB Flash Drive is
Controlled with Embedded Firmware

9.1.11.2 Manual Programming

Computer programs historically were manually input to the central processor via switches. An
instruction was represented by a configuration of on/off settings. After setting the configuration, an
execute button was pressed. This process was then repeated. Computer programs also historically
were manually input via paper tape or punched cards. After the medium was loaded, the starting
address was set via switches and the execute button pressed.

Figure 9.5: Switches for Manual Input on a Data General Nova 3

9.1.11.3 Automatic Program Generation

Generative programming is a style of computer programming that creates source code through
generic classes, prototypes, templates, aspects, and code generators to improve programmer
productivity. Source code is generated with programming tools such as a template processor
or an integrated development environment. The simplest form of source code generator is a
macro processor, such as the C preprocessor, which replaces patterns in source code according
to relatively simple rules.

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