ht82m99e Holtek Semiconductor Inc., ht82m99e Datasheet - Page 8

• Manufacturer Part Number: ht82m99e
• Description: Ht82m99e/ht82m99a -- Usb Mouse Encoder 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

Data Memory - RAM for Bank 1
The special function registers used in the USB interface
are located in RAM Bank1. In order to access Bank1
register, only the Indirect addressing pointer MP1 can
be used and the Bank register BP should be set to 1.
The RAM bank 1 mapping is as shown.
Address 00~1FH in RAM Bank0 and Bank1 are located
in the same Registers
Rev. 2.20
Bank 1 RAM Mapping
8
Indirect Addressing Register
Locations 00H and 02H are indirect addressing regis-
ters that are not physically implemented. Any read/write
operation on [00H] ([02H]) will access the data memory
pointed to by MP0 (MP1). Reading location 00H (02H)
indirectly will return the result 00H. Writing indirectly re-
sults in no operation.
The indirect addressing pointer (MP0) always points to
Bank0 RAM addresses no matter the value of Bank
Register (BP).
The indirect addressing pointer (MP1) can access
Bank0 or Bank1 RAM data according to the value of BP
which is set to 0 or 1 respectively.
The memory pointer registers (MP0 and MP1) are 7-bit
registers.
Accumulator
The accumulator is closely related to ALU operations. It
is also mapped to location 05H of the data memory and
can carry out immediate data operations. The data
movement between two data memory locations must
pass through the accumulator.
Arithmetic and Logic Unit - ALU
This circuit performs 8-bit arithmetic and logic opera-
tions. The ALU provides the following functions:
The ALU not only saves the results of a data operation
but also changes the status register.
Status Register - STATUS
This 8-bit register (0AH) contains the zero flag (Z), carry
flag (C), auxiliary carry flag (AC), overflow flag (OV),
power down flag (PDF), and watchdog time-out flag
(TO). It also records the status information and controls
the operation sequence.
With the exception of the TO and PDF flags, bits in the
status register can be altered by instructions like most
other registers. Any data written into the status register
will not change the TO or PDF flag. In addition, opera-
tions related to the status register may give different re-
sults from those intended.
Arithmetic operations (ADD, ADC, SUB, SBC, DAA)
Logic operations (AND, OR, XOR, CPL)
Rotation (RL, RR, RLC, RRC)
Increment and Decrement (INC, DEC)
Branch decision (SZ, SNZ, SIZ, SDZ ....)
HT82M99E/HT82M99A
April 16, 2008