In this system, numbers are represented in a decimal form, however each decimal digit is encoded using a four bit binary number. For example: The decimal number 1. BCD as follows: 1. Binary to ASCII character conversion. For each 8 chars call Convert.ToSByte(bits, 2). VSIP Program; Microsoft.NET; Microsoft Azure; Connect. I am trying to use the following code to convert 2 digit ASCII numbers to BCD number. ASCII to BCD conversion. Conversion of numbers between decimal and BCD is quite simple. To convert from decimal to BCD, simply write down the four bit binary pattern for each decimal digit. To convert from BCD to decimal, divide the number into groups of 4 bits and write down the corresponding decimal digit for each 4 bit group. There are a couple of variations on the BCD representation, namely packed and unpacked. An unpacked BCD number has only a single decimal digit stored in each data byte. In this case, the decimal digit will be in the low four bits and the upper 4 bits of the byte will be 0. ![]()
![]() In the packed BCD representation, two decimal digits are placed in each byte. Generally, the high order bits of the data byte contain the more significant decimal digit. An example: The following is a 1. BCD format: 0. 10. This is converted to a decimal number as follows: 0. Codes Conversion - Learning digital.The value is 5. 69. Another example: The same number in unpacked BCD (requires 3. The use of BCD to represent numbers isn’t as common as binary in most computer systems, as it is not as space efficient. In packed BCD, only 1. In unpacked BCD, only 1. A 1. 6 bit quantity can represent the range 0- 6. BCD and only 0- 9. BCD. EBCDICAbbreviation of Extended Binary- Coded Decimal Interchange Code. Pronounced eb- sih- dik, EBCDIC is an IBM code for representing characters as numbers. Although it is widely used on large IBM computers, most other computers, including PCs and Macintoshes, use ASCII codes. ASCII Character Encoding. The name ASCII is an acronym for: American Standard Code for Information Interchange. It is a character encoding standard developed several decades ago to provide a standard way for digital machines to encode characters. The ASCII code provides a mechanism for encoding alphabetic characters, numeric digits, and punctuation marks for use in representing text and numbers written using the Roman alphabet. As originally designed, it was a seven bit code. The seven bits allow the representation of 1. All of the alphabet, numeric digits and standard English punctuation marks are encoded. The ASCII standard was later extended to an eight bit code (which allows 2. European languages, which don’t appear in English. There are also numerous non- standard extensions to ASCII giving different encoding for the upper 1. For example, The character set encoded into the display card for the original IBM PC had a non- standard encoding for the upper character set. This is a non- standard extension that is in very wide spread use, and could be considered a standard in itself. Some important things to note about ASCII code: 1) The numeric digits, 0- 9, are encoded in sequence starting at 3. The upper case alphabetic characters are sequential beginning at 4. The lower case alphabetic characters are sequential beginning at 6. EE- 3. 14 Number Systems 7. The first 3. 2 characters (codes 0- 1. Fh) and 7. Fh are control characters. They do not have a standard symbol (glyph) associated with them. They are used for carriage control, and protocol purposes. They include 0. Dh (CR or carriage return), 0. Ah (LF or line feed), 0. Ch (FF or form feed), 0. BS or backspace). Most keyboards generate the control characters by holding down a control key (CTRL) and simultaneously pressing an alphabetic character key. The control code will have the same value as the lower five bits of the alphabetic key pressed. So, for example, the control character 0. Dh is carriage return. It can be generated by pressing CTRL- M. To get the full 3. CTRL and a punctuation key in combination. For example, the ESC (escape) character is generated by pressing CTRL- . Conversions Between Upper and Lower Case ASCII Letters. Notice on the ASCII code chart that the uppercase letters start at 4. In each case, the rest of the letters are consecutive and in alphabetic order. The difference between 4. Therefore the conversion between upper and lower case involves either adding or subtracting 2. To convert a lower case letter to upper case, subtract 2. It is important to note that you need to first ensure that you do in fact have an alphabetic character before performing the addition or subtraction. Ordinarily, a check should be made that the character is in the range 4. Ah for upper case or 6. Ah for lower case. Conversion Between ASCII and BCD. Notice also on the ASCII code chart that the numeric characters are in the range 3. Conversion between an ASCII encoded digit and an unpacked BCD digit can be accomplished by adding or subtracting 3. Subtract 3. 0h from an ASCII digit to get BCD, or add 3. BCD digit to get ASCII. Again, as with upper and lower case conversion for alphabetic characters, it is necessary to ensure that the character is in fact a numeric digit before performing the subtraction. The digit characters are in the range 3.
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