ROM Organization of Microcontroller 8051 | ROM Memory of 8051 | 8051 Memory Organization

Summary

This video lecture delves into the ROM organization of the 8051 microcontroller, explaining its internal 4KB ROM and the capacity to interface with an additional 64KB of external ROM. It clarifies the Harvard architecture, distinguishing between non-volatile program memory (ROM) and volatile data memory (RAM), essential for various embedded applications. The video also discusses how to utilize the EA^ bar pin for selecting between internal and external ROM, emphasizing the flexibility of memory management in the 8051 microcontroller.

Takeaways

• 😀 The 8051 microcontroller has a built-in 4 KB ROM and can interface with an additional 64 KB of external ROM.
• 🔍 The 8051 microcontroller features 128 bytes of internal RAM and can interface with up to 64 KB of external RAM.
• 🏛️ The 8051 follows the Harvard architecture, which means it has separate memory spaces for program and data.
• 📝 Program memory in ROM is non-volatile and fixed, while data memory in RAM is volatile and can change based on the application.
• 🔑 The EA/VPP pin determines the use of internal ROM; setting it to logic one indicates the use of the internal 4 KB ROM.
• 📍 The internal ROM has a fixed address range from 0x0000 to 0x0FFF in hexadecimal.
• 🌐 When using both internal and external ROM, the external ROM can be up to 64 KB and starts from address 0x1000 onwards.
• 🔄 The external ROM's address range can be determined by the programmer and can go up to 0xFFFF in hexadecimal.
• 🛠️ The 8051 is used in various embedded applications such as remote controls, microwave ovens, and washing machine timing controls.
• 📌 Fixed data like ASCII codes and seven-segment display data are stored in ROM because they are non-volatile and do not change.
• 🔄 Data that changes during program execution, such as temperature or time data, is stored in RAM as it is volatile.

Q & A

What is the ROM organization of the microcontroller 8051?

The microcontroller 8051 has an internal ROM of 4 KB and can interface externally with up to 64 KB of ROM.

What is the size of the internal RAM in the 8051 microcontroller?

The internal RAM of the 8051 microcontroller is 128 bytes in size.

How much external RAM can be interfaced with the 8051 microcontroller?

Up to 64 KB of external RAM can be interfaced with the 8051 microcontroller.

What is the Harvard architecture, as it relates to the 8051 microcontroller?

The Harvard architecture used by the 8051 microcontroller means it has separate program memory (ROM) and data memory (RAM), with program memory being non-volatile and data memory being volatile.

Why is the program memory in the 8051 considered non-volatile?

The program memory is non-volatile because the program instructions are fixed and do not change, unlike data which can vary with different applications and is stored in volatile RAM.

What is the significance of the EA/VPP pin in the context of the 8051 microcontroller's ROM usage?

The EA/VPP pin determines whether the 8051 microcontroller uses its internal ROM. When set to logic one (connected to VCC), it indicates the use of internal ROM. If set to zero, it signifies the use of only external ROM.

What happens when the EA/VPP pin is not connected to VCC in the 8051 microcontroller?

If the EA/VPP pin is not connected to VCC (set to zero), the 8051 microcontroller will not use its internal ROM and will rely solely on external ROM.

What is the default address range of the internal ROM in the 8051 microcontroller?

The default address range of the internal ROM in the 8051 microcontroller is from 0000h to 0FFFh.

Can the 8051 microcontroller use both internal and external ROMs simultaneously?

Yes, the 8051 microcontroller can use both internal and external ROMs, but the internal ROM must be enabled by setting the EA/VPP pin to logic one.

Why might a programmer choose to use only external ROM in the 8051 microcontroller?

A programmer might choose to use only external ROM if they require more memory than the internal 4 KB ROM provides, or if they need a specific size of ROM that is not available as a single IC, such as 60 KB.

What is the maximum size of external ROM that can be interfaced with the 8051 microcontroller?

The maximum size of external ROM that can be interfaced with the 8051 microcontroller is 64 KB.