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Okuma America Corporation
MACHINE DEFINITIONMACHINE DEFINITION
MACHINE DEFINITIONMACHINE DEFINITION
MACHINE DEFINITION
Rev. 8-21-01
MICROPROCESSOR
All operations that take place in the CNC are under direct control of the CPU. The CPU
directs the flow of data in a computer system. It constantly keeps track of what is taking
place within the control by performing a series of diagnostic operations. If any hazardous
conditions are detected it will shut down operations to prevent damage to the machine or
injury to an operator.
The microprocessor (µp) acts on instructions from programs stored in memory. It runs the
executive program (Control Software) which defines the capabilities of the machine. This
program initiates all operations and controls all data management functions. Without the
executive program the µp could not function.
The ALU determines axis position, spindle and axis speed, and performs program calcula-
tions in a CNC control. It also determines what to do if a limit switch is activated or an
overload is detected. The ALU performs all the calculations and logical decisions necessary
when processing information.
MEMORY
The computer cannot run without some means of storing information. There are numerous
types of memory available for this purpose and they fall into one of three categories: Perma-
nent, Long-Term, or Temporary.
Permanent Storage
Data resident in permanent storage is information that will be required for all applica-
tions. This data is not updated under normal operating conditions. This type of memory
is referred to as nonvolatile memory. The data is not lost when the machine is turned off.
The most common storage device in this category is ROM (Read Only Memory). ROM
comes in different styles.
PROM (Programmable Read Only Memory) - Data is stored in this device
through electronic means and cannot be erased. If data is unusable or must be
changed a new PROM must be made.
EPROM (Erasable Programmable Read Only Memory) - After data is stored in
the EPROM, it can later be erased by placing the device under an ultra violet light
source. This restores the EPROM to a blank state and new information can then
be entered. This device usually has a clear plastic window on top of the chip to
expose the components to the UV light source. Under normal operating condi-
tions this window is covered with a piece of tape to prevent accidental changing
of the data. On Okuma controls, this chip contains the System Boot Program.
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