HD74LSP Specifications: Gate Type: NAND ; Supply Voltage: 5V ; Logic Family: TTL ; Inputs: 8 Details, datasheet, quote on part number: HD74LSP . The semiconductor operations of Mitsubishi Electric and Hitachi were transferred to Renesas. Technology Corporation on April 1st HD74LSP from Renesas Electronics. Find the PDF Datasheet, Specifications and Distributor Information.

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Search the history of over billion web pages on the Internet. Full text of ” Radio Shack Hardware Manual: The CPU gathers instructions and data from memory, interprets and executes the instructions, and stores the results of the data operations into memory.

The 68B09E microprocessor is perhaps the most powerful 8-bit microprocessor available today. There are several ways to determine the “size” of a microprocessor whether it is 8-bit, bit, bit, or whatever. One way involves the number of data interconnecting lines the processor possesses. Another is the size of the internal registers and the size of the mathematical and logical operations supported by the processor. Although the 68B09E has an 8-bit data bus, internally it contains four bit registers and two additional 8-bit registers which may be linked together to form another bit register.

The 68B09E also supports some bit mathematical and logical operations. Therefore, although it is hd74lz374p an 8-bit processor, it hd74ls37p some of the power of the bit machines. Additional information may be obtained from the 68B09E data sheet. Note that there are sixteen address lines AO through A These address lines are output from the CPU and are used to select one of 65, different memory locations. Ddatasheet order of the devices and how they respond to the different lines are called the memory map.

The remaining lines on the CPU are used for control functions, both input control and output control. These clock signals must be present for the CPU to function. As shown in FigureQ is a quadrature clock signal which leads E by 90 degrees. The ones used by the Color Computer 3 are: Execution will continue after HALT is removed. Similar to IRQ, but masked by the F bit. It is faster because it doesn’t preserve all registers as do the other interrupts. Datadheet the interrupt routines, registers are preserved on the Stack to be restored upon receipt of the RTI Return-from-Interrupt instruction.

The TSC line is an input intended for use in multiprocessor or DMA environment and will cause the address and data lines to go into a datashert condition if high. Since the Color Computer 3 does not require multiprocessing, this line is permanently grounded. However, in the Color Computer 3, this timing is modified by the ACVC chip so that the addresses are available to the memory only during the active E time.

This presents no problem as long as the memory is sufficiently fast. Each memory chip is capable of storingbits 64K x 4any one of which may be accessed at any given time. Therefore, the memory array is said to be 64K x 8. In order to address a 64K location in each chip, 16 address lines are required. However, since the DRAM package has only 18 pins, the addresses are multiplexed into two groups of 8 and 8, called row address and column address.


The actual time depends on the access time of the DRAM. Figure shows the read and write timing cycles for DRAM.


Dynamic memory is called dynamic because it requires refreshing at periodic intervals in order to remember. The address count must toggle through all row address possibilities in 4 milli- seconds or less.

DRAM Timing 5. It contains the Master Oscillator, the frequency of which is controlled by a The Master Oscillator is divided by eight to give a 3. This reference signal is then divided by 4 or 2 again to provide the 0. Another function of this section is to provide address decoding and device selection fatasheet the computer. Due to the nature of the ROMs and in order to prevent data bus contention, the ROMs are enabled only during the E dh74ls374p of a read cycle.

This signal is provided to hd74ls34p video output datazheet through buffer Q2, Q3 and to the modulator. For the video generation circuit where the hd74ls374; register is designated via software, please refer to the Memory Map in section 1.

It has higher selectivity. This chip is designed to generate a composite video signal from baseband red, blue, green and composite sync input from sync mixer Qll and D15 – D The chip contains color subcarrier oscillator, voltage controlled 90 degrees phase shifter, two double-sideband suppressed carrier chroma modulators, RGB input matrix, and blanking level c 1 amp s.

For this purpose, the internal oscillator circuit of the IC is used. If the oscillator does not synchronize with the master oscillator, an apparent motion will exist whenever a color transition occurs. IC is a xatasheet operates in a divisor o output from the divider to the programmable div IC where a divisor o complete the count-down kHz. IC also contain comparator part, and it divided The phase compa generates a control vol proportion to the phase difference between thes The is connected ider part of f 4 is used to to This control voltage is passed through a simple R-C low pass filter and used to control a varactor diode D The capacitance of the varactor is changed to tune the 4.

This tuning allows the two oscillators to be synchronized at any time except during reset or power-on. This synchronization problem is solved by slightly shifting of the master oscillator frequency and the addition of a phase-locked-loop circuit.

The master crystal oscillator frequency of the PAL version is This allows the two oscillator to be dataxheet down to the horizontal frequency of Figure shows a block diagram of a Dataaheet. The two 8-bit data registers datawheet controlled by two data direction registers. These direction control registers are set up by the reset routine and normally will not be changed.

The control registers also handle device selection within the PIA. Two of the four lines function only as interrupt inputs, and the other two lines may be used as interrupt inputs or data outputs.

PIA IC5 is used mainly for the keyboard. Data register B pins is programmed as an output and is used to strobe the keyboard columns. The first seven lines of data register A pins are programmed as inputs and are used to read the keyboard rows. Pins 2 through 5 are also used as fire button inputs for the joysticks. PIA Block Diagram 5. The B side of this PIA is configured as outputs and connects to the column lines of the keyboard matrix. The A side of IC5 is configured as inputs and connects to the row lines of the keyboard matrix.


PIA IC5 is a select device. The use of PIA compensates for a possible increase in key contact resistance due to prolonged use and therefore should result in a highly reliable keyboard interface.

To read the keyboard, only one column is enabled by writing a zero in the bit that corresponds to that column and by writing ones in all the other bits. If a key is being pressed in that column, one of the input lines will be a zero, and the key location will correspond to the bit that is low.

By scanning each column in the keyboard, all of the keys may be checked. Figure shows the keyboard matrix. The most significant bit of data register A pin 9 is programmed as an input for the joystick interface. CA2 and CB2 pins 19 and 39 are used as outputs. These two lines select one of four joystick or sound inputs. PIA IC4 is used for several different functions. Pins of data register A are used for the 6-bit digital to analog converter.

HD74LS374P Datasheet

Pin 2 of register A is the input for data from the cassette. Pin 12 of register B is an input for the memory size. Pin 11 of register B is the single-bit sound output. Pin 10 is the RSC signal input pin. CA2 is an output used to control the cassette motor. CB1 is the cartridge interrupt input.

Whenever a cartridge is inserted into the computer, this input will interrupt BASIC and jump to the program in the cartridge. When power is applied to the CPU, it immediately attempts to fetch a vector and begin executing instructions. If there were no ROM, the CPU would read random floating states on the data bus, attempt to execute this, and promptly go haywire. As its name implies, it contains a Digital to Analog Converter.

HD74LSP Block Diagram – Renesas Electronics Corporation.

This chip also contains a sound multiplexer and the circuitry necessary to interface the joystick controllers to the microprocessor. Figure shows a block diagram of the DAC hdd74ls374p. The DAC performs most of the functions of this chip. Six bits of control are used by the DAC to specify a discrete internal analog level.

This level is one of the sound inputs to the sound multiplexer. It is dataasheet used as a reference for a comparator, the other input of which is one of the four joystick inputs. Finally, the DAC signal is attenuated and used as the cassette recording signal for data storage. There are two select inputs to the DAC chip: Sel A and Sel B.