The SN54L5670 and SN74LS670 MS1 16-bit TTL register film incorporate the equivalent of 98 gates. The register file is organized as 4 words of 4 bits each and separate on-chip decoding is provided for addressing the four word locations to either write-in or retrieve data. This permits simultaneous writing into one location and reading from another word location. Four data inputs are available which are used to supply the 4-bit word to be stored. Location of the word is determined by the write-address inputs A and B in conjunction with a write-enable signal. Data applied at the inputs should be in its true form That is, if a high-level signal is desired from the output, a high-level is applied at the data input for that particular bit location. The latch inputs are arranged so that new data will be accepted only if both internal address gate inputs are high. When this condition exists, data at the D input is transferred to the latch output. When the write-enable input, Ow, is high, the data in puts are inhibited and their levels can cause no change in the information stored in the internal latches. When the read-enable Input, Gn, is high, the data outputs are inhibited and go into the high-impedance stats

The 74LS669 is a synchronous 4-bit up/down counter. The LS669 is a 4-bit binary counter. For high speed counting applications, this presettable counter features an internal carry lookahead for cascading purposes. By clocking all flip-flops simultaneously so the outputs change coincident with each other (when instructed to do so by the count enable inputs and internal gating) synchronous operation is provided. This helps to eliminate output counting spikes, normally associated with asynchronous (ripple-clock) counters. The four master-slave flip-flops are triggered on the rising (positive-going) edge of the clock waveform by a buffered clock input. Circuitry of the load inputs allows loading with the carry-enable output of the cascaded counters. Because loading is synchronous, disabling of the counter by setting up a low level on the load input will cause the outputs to agree with the data inputs after the next clock pulse. Cascading counters for N-bit synchronous applications are provided by the carry look-ahead circuitry, without additional gating. Two count-enable inputs and a carry output help accomplish this function. Count-enable inputs (P and T) must both be low to count. The level of the up-down input determines the direction of the count. When the input level is low, the counter counts down, and when the input is high, the count is up. Input T is fed forward to enable the carry output. The carry output will now produce a low level output pulse with a duration ≈ equal to the high portion of the QA output when counting up and when counting down ≈ equal to the low portion of the QA output. This low level carry pulse may be utilized to enable successive cascaded stages. Regardless of the level of the clock input, transitions at the P or T inputs are allowed. By diode-clamping all inputs, transmission line effects are minimized which allows simplification of system design. Any changes at control inputs (ENABLE P, ENABLE T, LOAD, UP/DOWN) will have no effect on the operating mode until clocking occurs because of the fully independent clock circuits. Whether enabled, disabled, loading or counting, the function of the counter is dictated entirely by the conditions meeting the stable setup and hold times

The LS598 comes in a 20-pin package and has all the features of the LS597 plus 3-state 1/0 ports that pro vide parallel shift register outputs and also has multiplexed serial data inputs.

The ’LS573 is a high speed octal latch with buffered common Latch Enable (LE) and buffered common Output Enable (OE) inputs. This device is functionally identical to the ’LS373, but has different pinouts.

This device contains two independent gates each of which performs the logic NAND function.

The 74LS399 are Quad 2-Port Registers. They are the logical equivalent of a quad 2-input multiplexer followed by a quad 4-bit edge-triggered register. A Common Select input selects between two 4-bit in put ports (data sources). The selected data is transferred to the output register on the LOW-to-HIGH transition of the Clock input. The 74LS398 features Q and Q inputs, while the 74LS399 has only Q outputs.

These 8-bit registers feature totem-pole TRI-STATE outputs designed specifically for driving highly-capacitive or relatively low-impedance loads. The high-impedance state and increased high-logic level drive provide these registers with the capability of being connected directly to and driving the bus lines in a bus-organized system without need for interface or pull-up components. They are particularly attractive for implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers.

These Hex buffers and line drivers are designed specifically to improve both the performance and density of three-state memory address drivers, clock drivers, and bus oriented receivers and transmitters. The designer has choice of selected combinations of inverting and noninverting outputs, symmetrical G (active-low control) inputs. These devices feature high fan-out, improved fan-in, and can be used to drive terminated lines down to 133 ohms.