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Microprocessor Articles
Page 3 of 42
Intel 8212 in mode 0
The below fig shows clearly how 8212 works in the mode 0Fig: 8212 working in mode 0We use this mode generally when we want 8212 to function like an input port. An input device gets connected to DI7-0, and the microprocessor employed here receives the information on DOs ranging from D7-D0. Here in this mode STB acts as clock for the given latches. The latch which is of 8 bits in 8212 follows the series information which is present on DI7 to DI0 as long as STB is equal to 1. When the STB makes a transition, which is high ...
Read MoreIntel 8212 in mode 1
The figure below shows the working of 8212 in mode 1Fig: Working of 8212 in mode 1We use this mode generally when we want 8212 to function as an output port. Here, microprocessor drives DI7-0, and the device at the output receives the information on Do7-0. The clock to the latches is provided in this mode. 8212 latches the information on DI7-0 when the CS makes transition from high to low. The CS signal gets activates when INT* is transferred by the interrupts by the driven data transfer scheme which is always performed when desired. The buffer at the output ...
Read MoreApplications of 8212 in mode 0
We use Intel 8212 in variety of applications. Let us discuss applications of 8212 in Mode 0It acts as buffer which is gatedBus driver which is Bi-directionalFor Interrupting the input portTo supply of eight instructions based on RST.Intel 8212 as gated buffer: A weak logic signal is converted to a strong logic when 8212 works in logic 0. The outputs of 8212 in mode0 is capable of sinking the 15 mA in 0 state, and which proves that a minimum high output voltage of nearly 3.65 V is in the state 1. Intel8212 is always given backup when the input ...
Read MoreApplications of 8212 in mode 1
Let's discuss the Following two applicationsLow order address latchOutput port which is interrupting.Intel 8212 as low-order address latch − Here the low-order address lines and data lines are multiplexed and are available as AD7-0. It is convenient to have the address as many times and the separation of data on the different lines. Let's for an example, if we connect a chip like 2716 in an 8085-based system, the 2716 needs bit address of11 bits in its address pins, and here is separate 8 pins kept for data. Now connecting the AD7-0 pins of 8085 to the LS 8 address ...
Read More8085 program to exchange content of HL register pair with DE register pair
In this program we will see how to exchange the content of DE and HL pair.Problem StatementWrite 8085 Assembly language program to swap the content of HL and DE register pair.DiscussionThis process is very simple, 8085 has XCHG instruction. This instruction swaps DE and HL pair content. We are storing some values to DE and HL pair directly, and then exchange them using XCHG.InputDE = 5678H HL = CDEFHFlow DiagramProgramAddressHEX CodesMnemonicsCommentsF00016, 56MVI D, 56HLoad D with56HF0021E, 78MVI E, 78HLoad D with78HF00426, CDMVI H, CDHLoad D with CDHF0062E, EFMVI L, EFHLoad D withEFHF008EBXCHGExchange the content of DE and HLF00976HLTTerminate the programOutputDE ...
Read More8085 program to find sum of digits of 8 bit number
In this program we will see how to add the digits of an 8-bit number.Problem StatementWrite 8085 Assembly language program to add the digits of an 8-bit number stored in memory location 8000H.DiscussionTo get the digits of an 8-bit number, we can use the masking operation. At first we will mask the upper nibble, and then the lower nibble. After masking the lower nibble, we have to rotate it to the right to make it least significant nibble. Then we can simply add it to the stored nibble to get the sum.InputAddressData......80008A......ProgramAddressHEX CodesMnemonicsCommentsF0003A, 00, 80LDA 8000HLoad the number into AF0034FMOV ...
Read MoreUse of 8259 in an 8086-based system
The interrupt requests are accepted by 8259 from eight interrupting devices on the pin ranging fromIR0 toIR7. After that, it identifies the priority interrupt having the highest request from the inputs which are active. It is possible for us to configure the 8259 for the mode of operation of "fixed priority" mode.Here, among the priorities, IR0 has the highest and IR7 has the lowest. If the three inputs IR2, IR4, and IR6 are in active state, then IR2 will have is the highest priority interrupt request than the other active requests. We can mask the requests of the interrupts by installing ...
Read More8085 code to convert binary number to ASCII code
Now let us see a program of Intel 8085 Microprocessor. This program will convert binary or hexadecimal number to ASCII values.Problem StatementWrite 8085 Assembly language program to convert binary or Hexadecimal characters to ASCII values. DiscussionWe know that the ASCII of number 00H is 30H (48D), and ASCII of 09H is39H (57D). So all other numbers are in the range 30H to 39H. TheASCII value of 0AH is 41H (65D) and ASCII of 0FH is 46H (70D), so all other alphabets (B, C, D, E, F) are in the range 41H to 46H.Here we are providing hexadecimal digit at memory location ...
Read MoreRegisters used in 8259
The 8259 is a specialized I/O port chip. It is never used in the interfacing of I/O devices but is only used for controlling the interrupts in a microcomputer.8259 consists of A0 as the only address input pin. Hence for a microprocessor, only two addresses are possible for the 8259 ports. The two ports can be termed as low port and high port.The processor selects the low port when A0 = 0The processor selects the high port when A0 = 1The processor issues some words termed as command words to these ports so as to configure the 8259 better. There are ...
Read MoreImplied addressing mode in 8085 Microprocessor
In 8085 Instruction set, there is one mnemonic XCHG, which stands for eXCHanGe. This is an instruction to exchange contents of HL register pair with DE register pair. This instruction uses implied addressing mode. In the instruction, we don’t mention as “XCHG HL, DE”. It is implied that it will deal with HL and DEregister pairs. So we write only XCHG as mnemonic. That’s why it is called an implied addressing mode. As it is 1-Byte instruction, so It occupies only 1-Byte in the memory. After execution of this instruction, the content between H and D registers and L and ...
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