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Description Format of this Manual
Major terms used in this manual are explained below:
Term Meaning
I-BUS 16-bit wide bus used for internal instructions. Since the FR series uses
an internal Harvard architecture, independent buses are used for
instructions and data. A bus converter is connected to the I-BUS.
D-BUS Internal 32-bit wide data bus. Internal resources are connected to the
D-BUS.
C-BUS Internal multiplex bus. The C-BUS is connected to the I-BUS and D-
BUS via a switch. An external interface module is connected to the C-
BUS. Data and instructions are multiplexed in the external data bus.
R-BUS Internal 16-bit wide data bus. The R-BUS is connected to the D-BUS
via an adapter. Various I/O ports, the clock generator, and interrupt
controller are connected to the R-BUS. Since the R-BUS is 16 bits
wide in which addresses and data are multiplexed, it takes twice as
much or more cycle time than usual for the CPU to access these
resources.
E-unit Operation executing unit
φ
System clock output from the clock generator to each internal resource
connected to the R-BUS. The system clock at the highest speed
shows the same cycle as source oscillation but is divided into 1, 1/2, 1/
4, and 1/8 (or 1/2, 1/4, 1/8, and 1/16) by PCK1 and PCK0 of the clock
generator GCR register.
θ
System clock or operation clock for the CPU and resources connected
to a bus other than the R-BUS. The system clock at the highest speed
shows the same cycle as source oscillation but is divided into 1, 1/2, 1/
4, and 1/8 (or 1/2, 1/4, 1/8, and 1/16) by CCK1 and CCK0 of the clock
generator GCR register.