Logisim 8 bit register file download

It is note that the select signal from controller unit should be controlled like this. There is just one bit of the bit select signal which is high at a moment. Thus, we use 10 multiplexers 2 to 1 with the 1-bit select signal in bit input from control unit at the first stage of the module. Each multiplexer will output the input data if the 1-bit select signal is high, otherwise it will output zero. Then at the 2 nd stage, we use a OR gate to OR all the outputs of 10 multiplexers.

Since there is just 1 bit in the bit select signal is asserted HIGH, we will get the expected output at the output of the OR gate. R7out is asserted HIGH. Figure 3. The screenshot of Addsub module. The MUX will choose the result of which operation in the following:. Figure 4. The screenshot of 2-bit counter module.

Thus, we use 2 T-Flip Flop and connect to each other like in figure 4 and the OR gate is used to generate the clear signal in order to clear the counter. Brief about T Flip-Flop :. Function: If the T input is high, the T flip-flop changes state "toggles" whenever the clock input is rising-edge. If the T input is low, the flip-flop holds the previous value. This behavior is described by the characteristic equation :. We connect 2 T-FFs in the following diagram:. Figure 5. Table 1. Operation of 2-bit up counter u sing TFF.

Control Unit:. Table 2. Control signals. In the case of branch equal, both address and entire two general registers are involved, the general registers are compared using XOR gate, which would give a value of 0 when two registers are equal. Then the address is fetched by traveling through the system bus and put into PC to be the next address to be executed if and only if two registers have equal values. When without address, only one register is present, according to the OP-code, appropriate data-path will be selected and either the keypad buffer will be activated to store data present in the buffer to selected register; or digital display data-path will be activated for data in register to be stored.

There were nothing too tricky this driver, but I remember designing a circuit for converting a byte of data into 7-segment hexidecimal was so mundane and tedious. Some instructions are one byte, some are two bytes instructions.

Two byte instructions are in bold. Rxy indicates that it can be any of the two general purpose register. Since the CPU operates in four phases, not all instruction require execution in all of the phases, the table below details the execution phases of the instructions.

Before showing the multiplication program, we want to first introduce the grammar of the assembly. Since part of the project requirement was to create a program on the designed CPU that performs the multiplication of two numbers entered in the numpad. For the ease of reproducibility and debugging, an assembler was created. The assembler take input of the multiplication assembly program depicted above and outputs the corresponding machine code for the CPU as a Logisim compatible RAM-image:.

Being a course project and under pressured time constraint, the assembler has the following limitations:. ROM for converting numpad decimal input into binary Decimal to binary conversion was rather easy and can be designed cleanly.

Follow Logisim Logisim Web Site. Mit einem Experten sprechen. User Ratings 4. User Reviews Filter Reviews: All. Very useful and also quite intuitive in many respects. A few glitches might be in the codes. A save and reload just fixes that. Thank you very much for the program! Thank you for distributing it under a free open source license! I think if java 5. Report inappropriate content. Thanks for helping keep SourceForge clean. X You seem to have CSS turned off. Briefly describe the problem required :.