Suppose we have the chip select circuit as shown in the below figure, then what is the address range for the RAM?Fig. Chip selection that results in multiple address range.A15 and A14 pins are used for the selection of Random Access Memory, and pins ranging from A10 to A0 are used for the selection of location in RAM. But the value of the pins A13, A12 and A11 have non-dependent value. They play no role for selection of chip or location on RANDOM ACCESS MEMORY. Hence they are termed as don't cares and called x for more signification.We have eight ... Read More

Let us assume that we have a RAM chip of 2K x 8, It signifies that, we have 2 x 1024 = 2048 memory locations having information of 8 bits at each location. For selecting one of 2K = 211 memory locations in chip, there should be exactly input pins of 11 address lines. For bidirectional data transfer scheme, there should be eight pin involved in this process. The processor action involved in it is signified by the input pins RD* and WR*. Two pins are specified for grounding process of the pin and connecting of Direct Current of +5 ... Read More

The master of microcomputer system is the microprocessor since all the operations of a computer are controlled by the microprocessor, the control unit often called as (CU) is found in the microprocessor. In the microcomputer system apart from processor there are several chips of RAM, CHIPS of EPROM and other Input Output port chips, timer 8253 is also present. But surprisingly at any moment of time the remains with only one of the chip. By activation of the chip selection the processor, the selection of the chip of the processor is done. Hence except the processor all chips must have ... Read More

Running the program in Single-Step Mode:The single step mode is very useful for finding our program which has not yielded the desired outcomes after being executed in a single burst. We use it for program debugging. Similarly, like the operation to be executed singly ‘S’ is typed at the ‘>’ prompt. We can notice clearly that the change of address occurs after S. The given system clearly prompts which is stated below:The address of starting is: xxxx - yy/where the memory address is xxxx and the content of the located memory is yy which allows for responding the user ... Read More

In a single operation, we can run the entire program of 8085. We run the entire program in this mode so that we can get the accurate results. If the process is unsuccessful a single-stepping by the entire program is attempted.We type ‘G’ at the prompt ‘>’. By noticing the absence of change of address after G. The prompting of the system are as follows:The address of starting is: xxxx - yy/where the memory address is xxxx and the content of the memory location is yy. Which allows the user for responding with the desired address of starting. If ... Read More

DATA FILE MODE in8085 MicroprocessorWe can refer to ‘X8085 cross-assembler’ manual for details.The format of Intel Hex: We have shown the MULT.HEX file to give a brief description at a glance.:01 C100 00 04 3A:01 C200 00 05 38:02 C300 00 00 00 3B:10 C000 00 21 00 C1 5E 16 00 21 00 C2 7E 21 00 00FE 00 CA 90:10 C010 00 17 C0 19 3D C2 12 C0 22 F7 FF 22 00C3 CD BC 06 D3:01 C020 00 76 A9:00 0000 01 FFThere are several lines which the file consists of which are termed as records. ... Read More

We have seen previously that the linker is invoked in three modes i.e. they are command line mode, prompt mode and data file mode. For the linker to be run in this mode we type ‘LINK85 -C MULT.OBJ’ along with the change of address. In the above command simply “MULT” is enough instead of the command ‘MULT.OBJ’. We run the linker in this Command Mode type as by simply the following steps: Simply ‘MULT’ is more than enough instead of ‘MULT.OBJ’ in the command above. The linker in running command mode is indicated by the option -C. The command which ... Read More

We have seen previously that the linker is invoked in three modes i.e. they are command line mode, prompt mode and data file mode. In the Prompt mode the linker is run by simply typing the ‘LINK85’. Responding to the prompt the linker requests the user for the file name. In the given example, responding with ‘MULT.OBJ’ is there in fact MULT is enough.The linker prompts for the address of the offset. The value of the offset which is input by means of the user is finally added to the value of any ORG statements in the file. In response ... Read More

The file MULT.ASM which is created by using an editor is simply a text file. We cannot execute this file directly. At first we have to assemble the file, and then we have to link it. The step of assembly the translation of the program of assembly language to machine code requires the generation of a .OBJ file.Now a .HEX file is generated by using a linker. We have seen previously that how the naming of the input and output file is done.Input filenameThe source name of the file must be responded by the user. In the given example the ... Read More

Generation of .OBJ file by using a cross-assembler:The file assembly language program file, e.g. MULT.ASM which is created by using an editor is simply a text file. We cannot execute this file directly. At first we have to assemble the file, and then we have to link it. The step of assembly the translation of the program of assembly language to machine code requires the generation of a .OBJ file.We have used some examples in the text of ‘2500 A.D i.e. the 8085 cross-assembler of version 4.01.In the prompt mode the translation is:We type ‘X8085’ just for performing the translation ... Read More