OS Problem Set Introduction The following machine description will provide the basis for this assignment. You will build a virtual machine/operating system for the machine described below that will accept programs in the target machine language. The details for this assignment are presented below following the machine description. MICROPROGRAMMING/MACHINE DISCRIPTION The following is a description of a machine called SIMMAC that contains the following: 512 32-bit words of memory (memory is word addressable). Each Instruction consists of a 16-bit opcode and a 16-bit operand. An ALU for performing mathematical operations. Registers ACC Accumulator; A 32-bit register involved in all arithmetic operations. One of the operands in each arithmetic operation must be in the Accumulator; the other must be in primary storage. PSIAR Primary Storage Instruction Address Register; This 16-bit register points to the location in primary storage of the next machine language instruction to be executed. SAR Storage Address Register; This 16-bit register is involved in all references to primary storage. It holds the address of the location in primary storage being read from or written to. SDR Storage Data Register; This 32-bit register is also involved in all references to primary storage. It holds the data being written to or receives the data being read from primary storage at the location specified in the SAR. TMPR Temporary Register; This 32-bit register is used to extract the address portion (rightmost 16-bits) of the machine instruction in the SDR so that it may be placed in the SAR. (No SDR to SAR 2 transfer.) CSIAR Control Storage Instruction Address Register; This register points to the location of the next micro-instruction (in control storage) to be executed. IR Instruction Register; This register contains the current instruction being executed. MIR Micro-instruction Register; This register contains the current micro-instruction being executed. Register Transfers (REG is ACC, PSIAR, or TMPR): SDR = REG REG = SDR SAR = REG Primary Storage Operations: READ Data from primary storage location named in the SAR is placed in the SDR. WRITE Data in the SDR is placed in primary storage location named in the SAR. Sequencing operations: CSIAR = CSIAR + 1 CSIAR = decoded SDR CSIAR = constant SKIP = (add 2 to CSIAR if ACC=0; else add 1) Operations involving the accumulator: ACC = ACC + REG ACC = ACC - REG ACC = REG REG = ACC ACC = REG + 1 Instruction fetch: 3 (00) SAR = PSIAR (01) READ (02) IR = SDR (03) SDR = decoded IR (Operand) (04) CSIAR = decoded IR (OP CODE) ADD (Opcode 10): (10) TMPR = ACC (11) ACC = PSIAR + 1 (12) PSIAR = ACC (13) ACC = TMPR (14) TMPR = SDR (15) SAR = TMPR (16) READ (17) TMPR = SDR (18) ACC = ACC + TMPR (19) CSIAR = 0 SUB (Opcode 20): (20) TMPR = ACC (21) ACC = PSIAR + 1 (22) PSIAR = ACC (23) ACC = TMPR (24) TMPR = SDR (25) SAR = TMPR (26) READ (27) TMPR = SDR (28) ACC = ACC - TMPR (29) CSIAR = 0 LOAD (LDA, Opcode 30): (30) TMPR = ACC (31) ACC = PSIAR + 1 (32) PSIAR = ACC (33) ACC = TMPR (34) TMPR = SDR (35) SAR = TMPR (36) READ (37) ACC = SDR (38) CSIAR = 0 STORE (Name STR, Opcode 40): 4 (40) TMPR = ACC (41) ACC = PSIAR + 1 (42) PSIAR = ACC (43) ACC = TMPR (44) TMPR = SDR (45) SAR = TMPR (46) SDR = ACC (47) WRITE (48) CSIAR = 0 BRANCH (Name BRH, Opcode 50): (50) PSIAR = SDR (51) CSIAR = 0 COND BRANCH (Name CBR, Opcode 60): (60) SKIP (61) CSIAR = 64 (62) PSIAR = SDR (63) CSIAR = 0 (64) TMPR = ACC (65) ACC = PSIAR + 1 (65) PSIAR = ACC (66) ACC = TMPR (67) CSIAR = 0 LOAD IMMEDIATE (LDI, Opcode 70): (70) ACC = PSIAR + 1 (71) PSIAR = ACC (72) ACC = SDR (73) CSIAR = 0 5 SIMMAC Programming Language Description Addition Usage: ADD
holds the value to add to the accumulator. Subtraction Usage: SUB
holds the value to subtract from the accumulator. Load Usage: LDA
holds the value to load in to the accumulator. Load Immediate Usage: LDI number Where number is the value to load in to the accumulator. Store Usage: STR
is the storage location for the contents of the accumulator. Branch Usage: BRH
is the target of the absolute branch. 6 Conditional Branch Usage: CBR
is the target of an absolute branch if the accumulator is zero. Project Description Design and implement a program to simulate the operation of the SIMMAC based on the descriptions above. Add a HALT instruction that dumps the contents of all registers and memory and then prints an "End of Job" message. Your project must implement multi-tasking in a single queue using a round-robin scheduling discipline. You will implement process entities (jobs) that will allow your machine to run several SIMMAC machine-language programs. In order to accomplish you will define a Process Control Block (PCB) data structure that will be created for each job in your system. For this assignment assume each SIMMAC instruction is equivalent to one clock cycle. Additionally the time quantum value for round-robin scheduling is an integer multiple of a clock cycle. The quantum value is to be set on the command line or prompted for during initialization. You will define the notion of an interrupt handler that will process a time quantum for each running job. On each job switch, you will print some state information such as which job will be loaded and the current state of the job queues. Your version of SIMMAC will then run multiple SIMMAC machine language programs simultaneously. These programs will test the ability of your SIMMAC to handle multitasking and scheduling. You must design your system such that all SIMMAC machine programs are loaded from text files. The SIMMAC must be designed to take command line arguments or to prompt for input files in addition to the previously specified items. By this mechanism, all SIMMAC language programs will be loaded. Since there is the LDI command, all data can be loaded into SIMMAC memory using SIMMAC programming statements. You must develop SIMMAC language programs to be run on your SIMMAC machine. There must be at least three different programs that exercise the system and are of significant length to demonstrate the multitasking/scheduling ability of your system. You must clearly document your programs so that it is clear as to the logic and intent of each SIMMAC language program. 7 Each line of any SIMMAC program must have the following format: Opcode Operand You will be responsible for turning in the system design document, source code of your version of SIMMAC (this code must be appropriately commented & readable), an executable version of your SIMMAC, and the output generated from your SIMMAC programs running on your version of SIMMAC.
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