![]() To convert binary to gray code, bring down the most siginificant digit of the given binary number, because, the first digit or most siginificant digit of the gray code number is same as the binary number. Be careful with the order of the registers when translating into machine code, as the Rd is the last register in machine code. The below steps & solved example may useful to know how to perform binary to gray code conversion. This can be checked by entering the instruction in MARS, and assembling it to see the resulting machine code. Murray designed the code to minimize the wear on the machinery. In 1901, the code was improved by Donald Murray. It was a 5-bit code that became known as the International Telegraph Alphabet No 1 (ITA1). This results in the following instruction. The original Baudot code was invented by melie Baudot in 1870. To make it readable, the bits are divided into groups of 4 bits, and these 4 bit values translated into hex. This is as hard to type as it is to read. Thus the instruction " add $t0, $t1, $t2" translate into the bit string Figure 4-4: Machine code for add $t0, $t1, $t2 The result is the following R-format instruction. The shamt is 00000 as there are no bits being shifted. $t2 is also register $10, or 01010, so 01010 is placed in the R t field. $t1 is also register $9, or 01001, so 01001 is placed in the R s field $t0 is also register $8, or 01000, so 01000 is placed in the R d field. These are placed into the op-code and function fields of the R format instruction shown in figure 4-5 below. So the 6 bits for the op-code translate to 00 0000, and the 6 bits for the function translate to 10 0000. Both are generally called hex values, so this text will do so as well. So the first number in the op-code and function is 0.3, and the second is 0.f. If there is only one number with no "/", it is the op-code, and there is no function.īoth the op-code and the function are 6 bits, divided into a 2 bit number and a 4 bit number. If the instruction has a function, the number to the left of the "/" is the op- code, and the number to the right of the "/" is the function. Note that the function is used only for R format instructions. ![]() The op-code/function field is made up of two numbers, the first is the op-code, and the second is the function. The MIPS Greensheet specifies the add instruction as an R-format instruction and the op- code/function for the add as 0/20. ![]() This section will translate the following add instruction to machine code. ![]()
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