RL7-RL0: Return lines are inputs used to sense key depression in the keyboard matrix. Shift: Shift connects to Shift key on keyboard. SL3-SL0: Scan line outputs scan both the keyboard and displays.
Q. What is the purpose of 8279?
8279 programmable keyboard/display controller is designed by Intel that interfaces a keyboard with the CPU. The keyboard first scans the keyboard and identifies if any key has been pressed. It then sends their relative response of the pressed key to the CPU and vice-a-versa.
Table of Contents
- Q. What is the purpose of 8279?
- Q. How many major sections are in 8279?
- Q. How many character definitions are possible in 8279?
- Q. Which mode allows 8 16 character multiplexed display?
- Q. Why 8087 is referred to as coprocessor?
- Q. For what purpose Vo pin of 16 * 2 LCD is used?
- Q. Which instruction is used to clear LCD?
- Q. What is the function of RS R W and E pins of LCD?
- Q. Which LCD command is used to increment cursor?
- Q. What can be done to enable LCD?
- Q. How LCD can be enabled?
- Q. Do LCD screens need a backlight?
- Q. What are the disadvantages of LCD?
Q. How many major sections are in 8279?
In the Polled mode, the CPU periodically reads an internal flag of 8279 to check whether any key is pressed or not with key pressure. BLOCK DIAGRAM OF 8279: The functional block diagram of 8279 is shown in Figure 3.6. 1. The four major sections of 8279 are keyboard, scan, display and CPU interface.
Q. How many character definitions are possible in 8279?
Display Scan : In this mode 8279 provides 8 or 16 character multiplexed displays those can be organized as dual 4- bit or single 8-bit display units.
Q. Which mode allows 8 16 character multiplexed display?
Display Scan
Q. Why 8087 is referred to as coprocessor?
2. Why 8087 is referred to as Coprocessor? i) Because 8087 is used in parallel with main processor in a system, rather than serving as a main processor itself. ii) Because 8087 is used in serial with main processor in a system, rather than serving as a main processor itself.
Q. For what purpose Vo pin of 16 * 2 LCD is used?
An LCD is an electronic display module that uses liquid crystal to produce a visible image. The 16×2 LCD display is a very basic module commonly used in DIYs and circuits. The 16×2 translates o a display 16 characters per line in 2 such lines….16X2 LCD pinout diagram.
| Pin No. | Function | Name |
|---|---|---|
| 16 | Backlight Ground (0V) | Led- |
Q. Which instruction is used to clear LCD?
LCD Commands
| Instruction | Code | |
|---|---|---|
| RS | DB1 | |
| Clear display | 0 | 0 |
| Cursor home | 0 | 1 |
| Entry mode set | 0 | I/D |
Q. What is the function of RS R W and E pins of LCD?
The R/W (read/write) bit tells the LCD whether we wish to read from or to write to RAM. The E (enable) bit tells the LCD when it should read the data lines. All of these bits need to be connected to different pins on the board.
Q. Which LCD command is used to increment cursor?
lcd commands and understanding of LCD module
| Code (Hex) | working of lcd commands |
|---|---|
| 2 | Return home |
| 4 | Decrement cursor (shift cursor to left) |
| 6 | Increment cursor (shift cursor to right) |
| 5 | Shift display right |
Q. What can be done to enable LCD?
We use the digital pins on the Arduino to talk to the LCD and display what we want on it. Apart from these lines, there is also an enable pin, RS pin and an RW pin. The backlight on the LCD is activated when you give 5V from the Arduino to pin 15 on the LCD and by grounding pin 16.
Q. How LCD can be enabled?
Enable(EN): This pin is used to send the enable trigger to LCD. After sending the data/cmd, Selecting the data/cmd register, Selecting the Write operation. A HIGH-to-LOW pulse has to be send on this enable pin which will latch the info into the LCD register and triggers the LCD to act accordingly.
Q. Do LCD screens need a backlight?
The liquid pixels within an LCD device don’t illuminate on their own. Rather, they require illumination from a separate component, known as a backlight. The bottom line is that a backlight is an essential component in LCDs. Without a backlight, an LCD display device will remain black, rendering it unviewable.
Q. What are the disadvantages of LCD?
Disadvantages of LCD :
- Slightly more expensive than CRT.
- Can’t act as a portal to another dimension.
- Suffer from a motion blur effect.
- High refresh rate.
- Like the backlight ages, it can change colors slightly.
- The aspect ratio and resolution are fixed.
- Not proficient at producing black or very dark grays colors.
