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BCD numbers can be represented in two ways in integer registers: packed decimal and unpacked decimal. Packed (4 bits) In packed decimal representation a decimal digit is stored in one nibble. The values 10 to 15 are not used. [2] Unpacked (8 bits) In unpacked decimal representation a decimal digit is stored in one byte. The values 10 to 255 are ...
Today, few consumer-grade PC-compatible computers include COM ports, [3] though some of them do still include a COM header on the motherboard. [4] After the RS-232 COM port was removed from most consumer-grade computers, an external USB-to-UART serial adapter cable was used to compensate for the loss. A major supplier of these chips is FTDI.
This table illustrates an example of an 8 bit signed decimal value using the two's complement method. The MSb most significant bit has a negative weight in signed integers, in this case -2 7 = -128. The other bits have positive weights. The lsb (least significant bit) has weight 1. The signed value is in this case -128+2 = -126.
That is, the value of an octal "10" is the same as a decimal "8", an octal "20" is a decimal "16", and so on. In a hexadecimal system, there are 16 digits, 0 through 9 followed, by convention, with A through F. That is, a hexadecimal "10" is the same as a decimal "16" and a hexadecimal "20" is the same as a decimal "32".
For example, on the original IBM PC, a male D-sub was an RS-232-C DTE port (with a non-standard current loop interface on reserved pins), but the female D-sub connector on the same PC model was used for the parallel "Centronics" printer port. Some personal computers put non-standard voltages or signals on some pins of their serial ports.
Serial computer buses have become more common even at shorter distances, as improved signal integrity and transmission speeds in newer serial technologies have begun to outweigh the parallel bus's advantage of simplicity (no need for serializer and deserializer, or SerDes) and to outstrip its disadvantages (clock skew, interconnect density).
In computers, a serial decimal numeric representation is one in which ten bits are reserved for each digit, with a different bit turned on depending on which of the ten possible digits is intended. ENIAC and CALDIC used this representation.
On the other hand, a hard disk whose capacity is specified by the manufacturer as "10 gigabytes" or "10 GB", holds 10 × 10 9 = 10 000 000 000 bytes, or a little more than that, but less than 10 × 2 30 = 10 737 418 240 and a file whose size is listed as "2.3 GB" may have a size closer to 2.3 × 2 30 ≈ 2 470 000 000 or to 2.3 × 10 9 = 2 300 ...