PIC16HV540 Microchip Technology, PIC16HV540 Datasheet - Page 7

• Manufacturer Part Number: PIC16HV540
• Description: Enhanced PIC16C54 EPROM-Based 8-Bit CMOS Microcontroller
• Manufacturer: Microchip Technology

3.0
The high performance of the PIC16HV540 can be
attributed to a number of architectural features com-
monly found in RISC microprocessors. To begin with,
the PIC16HV540 uses a Harvard architecture in which
program and data are accessed on separate buses.
This improves bandwidth over traditional von Neumann
architecture where program and data are fetched on
the same bus. Separating program and data memory
further allows instructions to be sized differently than
the 8-bit wide data word. Instruction opcodes are 12-
bits wide making it possible to have all single word
instructions. A 12-bit wide program memory access
bus fetches a 12-bit instruction in a single cycle. A two-
stage pipeline overlaps fetch and execution of instruc-
tions. Consequently, all instructions (33) execute in a
single cycle (200ns @ 20MHz) except for program
branches.
The PIC16HV540 address 512 x 12 of program mem-
ory. All program memory is internal.
The PIC16HV540 can directly or indirectly address its
register files and data memory. All special function reg-
isters including the program counter are mapped in the
data memory. The PIC16HV540 has a highly orthogo-
nal (symmetrical) instruction set that makes it possible
to carry out any operation on any register using any
addressing mode. This symmetrical nature and lack of
‘special optimal situations’ make programming with the
PIC16HV540 simple yet efficient. In addition, the learn-
ing curve is reduced significantly.
2000 Microchip Technology Inc.
ARCHITECTURAL OVERVIEW
Preliminary
The PIC16HV540 device contains an 8-bit ALU and
working register. The ALU is a general purpose arith-
metic unit. It performs arithmetic and Boolean functions
between data in the working register and any register
file.
The ALU is 8-bits wide and capable of addition, sub-
traction, shift and logical operations. Unless otherwise
mentioned, arithmetic operations are two's comple-
ment in nature. In two-operand instructions, typically
one operand is the W (working) register. The other
operand is either a file register or an immediate con-
stant. In single operand instructions, the operand is
either the W register or a file register.
The W register is an 8-bit working register used for ALU
operations. It is not an addressable register.
Depending on the instruction executed, the ALU may
affect the values of the Carry (C), Digit Carry (DC),
and Zero (Z) bits in the STATUS register. The C and
DC bits operate as a borrow and digit borrow out bit,
respectively, in subtraction. See the SUBWF and ADDWF
instructions for examples.
A simplified block diagram is shown in Figure 3-1, with
the corresponding device pins described in Table 3-1.
PIC16HV540
DS40197B-page 7