Dynamic Shift Registers - Bitsavers - Trailing-Edge

ROM Code ConvertersMM4220BM/MM5220BM sine look-up tablegeneral descriptionThe MM4220BM/MM5220BM is a 1024-monolithicMaS read only memory that has beenprogrammed to solve for the sine value x of aknown angle 8; i.e., to obtain the solution of theequation x = sin 8.Values of 8 are defined in the look up table for0° ~ 8 < 90° (quadrant I) which has correspondingsolutions of 0 ~ x < 1. For values of90° < 8 < 180° (quadrant II), enter the complement(180° - 8) to obtain the correct solution.Solutions for quadrants III and I V differ in signwith I and II. This is summarized in Table 1.This input is divided into 128 parts for 8 in eachquadrant. Thus, the appropriate input address is(8 1 /90°)(128) to the nearest whole integer. Theactual input code to the ROM is the input addressexpressed in binary, with A1 being the mostsignificant bit.The output is the value of X expressed in binary.The output lines B 1 , B2 , ..... B8 are binary placevalues 1/2, 1/4, ...... 1/256. The sign for negativevalues of X is externally generated.The 8 bit output code has been rounded off froma larger word code, i.e., where Ag was a binary"1" it carried into the LSB of the eight bit code,where Ag was a binary "0" it was simply dropped.EXAMPLEFind the sine of 45~The input address is (45/90) 128 = 64 or1000000, as expressed in binary. The convertergenerates the output .10110101 whose decimalequivalent is 0.707131. Thus, sin 45° = 0.707.Find the sine of 210~This value is in quadrant III; therefore 8 1 = 210° -180° = 30°. The input address is then (30/90)128 == 43 to the nearest whole integer. The binaryinput to the ROM is then 0101011. The outputvalue is .10000001 or 0.503906. Thus, sin 210° =-0.504, with the sign generated by the externallogic. The solution is within 1 %; note that address43 is actually equal to 30.23°.device characteristicsFor full electrical, environmental and mechanicaldetails refer to the MM4220/MM5220 1024-bit readonly memory data sheet.typical application-I1V----__________ .-..... --,VooA,24 VooA, B,6.BI