The timing signal that is active after the decoding is T 3. Multiple input OR gates are included in the diagramīecause there are other control functions that will initiate similar operations. T1 are connected to the control inputs of the registers, the memory, and theīus selection inputs. The next clock transition initiates the read and increment operations sinceįigure above duplicates a portion of the bus system and shows how T0 and
Increment PC by enabling the INR input of PC.
Transfer the content of the bus to IR by enabling the LD input of IR.Ĥ. Place the content of memory onto the bus by making S 2S 1S 0 = 111.ģ. It is necessary to use timing signal T1 to provide the following connections inĢ. In order to implement the second statement : The next clock transition initiates the transfer from PC to AR since T0 = 1. Transfer the content of the bus to AR by enabling the LD input of AR. Place the content of PC onto the bus by making the bus selection inputsĢ. To provide the data path for the transfer of PC toĪR we must apply timing signal T0 to achieve the following connection: Įach clock pulse to produce the sequence T0, T1, and T2įigure above shows how the first two register transfer statements are implemented Part of the instruction is transferred to AR. In IR is decoded, the indirect bit is transferred to flip-flop I, and the address In the instruction register IR with the clock transition associated with timing signal T1.Īt the same time, PC is incremented by one to prepare it for theĪddress of the next instruction in the program. The instruction read from memory is then placed To transfer the address from PC to AR during the clock transition associated Since only AR is connected to the address inputs of memory, it is necessary Rnicrooperations for the fetch and decode phases can be specified by the So that the timing signals go through a sequence T0, T1, T2, and so on. After each clock pulse, SC is incremented by one, The sequence counter SC is cleared to 0, providing aĭecoded timing signal T0. Initially, the program counter PC is loaded with the address of the first instruction This process continues indefinitely unless a Upon the completion of step 4, the control goes back to step 1 to fetch, decode,Īnd execute the next instruction. Read the effective address from memory if the instruction has an indirect In the basic computer each instruction cycleģ. Each instruction cycle in turn is subdivided into a The program is executed in the computer by going through aĬycle for each instruction.
Please try avoiding to commiting lfm files when you did not change anything (lazarus writes windows arrangement into lfm's which we don't want to commit).A program residing in the memory unit of the computer consists of a sequence The desktop file should be ready to use and goes into
TODO: Use a scalable vektor graphics instead of png and fix paths in source code The icon src/cpusim.png should be located atĪnd the contents of the 'Examples' directory in To open the project in the Lazarus IDE just open the cpusim.lpi as a project. Skip the build-mode flag in order to build in debug mode. Lazbuild -build-mode=release -widgetset=qt -build-all -recursive cpusim.lpi You need to run lazarus before this at least once to set up the paths.Įxecute to build in release mode (optmizations such as O3 flags): There's already an (incomplete) PKGBUILD available in the AUR ( upstream URL) Building & Contributing Dependencies Included with the source code if you would like to read the terms of the license.īinary releases together with the corresponding source code can be found in the releases section of our GitHub page. This program is licensed under the GPL v.3. No special "games" or traffic lights as outputs available.
This project started out as a school-project and to be a drop-in replacement for the aging sms32 Microprocessor Simulator but with some changes in mind.