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The 74181 is a 7400 series medium-scale integration (MSI) TTL integrated circuit, containing the equivalent of 75 logic gates [3] and most commonly packaged as a 24-pin DIP. The 4-bit wide ALU can perform all the traditional add / subtract / decrement operations with or without carry, as well as AND / NAND, OR / NOR, XOR , and shift .
The de facto standard for 3.5 inch drives uses a 34-pin header mating to an IDC Berg connector, collectively slightly smaller than the PCB edge pin connector and mating socket used for the 5¼ inch standard but with the same 34 pin definitions as the 5¼ inch standard. [7] A separate connector is provided for DC power. [1]
Conversely, the 4000-series has "borrowed" from the 7400 series – such as the CD40193 and CD40161 being pin-for-pin functional replacements for 74C193 and 74C161. Older TTL parts made by manufacturers such as Signetics , Motorola , Mullard and Siemens may have different numeric prefix and numbering series entirely, such as in the European FJ ...
The first part number in the series, the 7400, is a 14-pin IC containing four two-input NAND gates. Each gate uses two input pins and one output pin, with the remaining two pins being power (+5 V) and ground. This part was made in various through-hole and surface-mount packages, including flat pack and plastic/ceramic dual in-line.
Moving the HDD controller from the interface card to the disk drive helped to standardize the host/controller interface, reduce the programming complexity in the host device driver, and reduced system cost and complexity. The 40-pin IDE/ATA connection transfers 16 bits of data at a time on the data cable.
Many types of Berg connectors exist. Some of the more familiar ones used in IBM PC compatibles are: the four-pin polarized Berg connectors used to connect 3½-inch floppy disk drive units to the power supply unit, usually referred to as simply a "floppy power connector", but often also referred to as LP4. This connector has a 2.50 mm (0.098 in ...
A CPU built using the 74181 will use more power and dissipate more heat than any modern microprocessor of equal computing power. A CPU built using the 74181 or even faster discrete logic families (like ECL) is limited by speed of light delays inherent in the size of the chips and the spacing between them. Believe it or not, part of the reason ...
The open collector transistor can be rated to withstand a higher voltage than the chip supply voltage. This technique is commonly used by logic circuits operating at 5 V or lower to drive higher voltage devices such as electric motors, LEDs in series, [8] 12 V relays, 50 V vacuum fluorescent displays, or Nixie tubes requiring more than 100 V.