On-chip RAM is 128 bytes, ranging from address 00H to 7FH.

The first 32 bytes (00H–1FH) of on-chip RAM are designated as the working register area, which can be used for general-purpose data storage and function calls.

In addition, the on-chip RAM includes 128 bit-addressable bits, spread across 16 byte locations. These bits can be individually accessed and manipulated, making them ideal for tasks that require precise control over individual bits.

The bit addresses range from 00H to 7FH, and they are located within the 20H–2FH memory block. This area is often used for storing flags or status information in microcontroller applications.

Among the 21 special function registers (SFRs), some bits can also be bit-addressed if their addresses are divisible by 8. This allows direct manipulation of specific bits in SFRs, improving efficiency in low-level programming.

Off-chip RAM is addressable up to 64KB, covering the range from 0000H to FFFFH. This provides additional memory space for larger programs or data storage beyond the on-chip capacity.

Similarly, off-chip ROM is also addressable up to 64KB, with the same address range of 0000H to FFFFH. This is commonly used for storing program code that exceeds the on-chip ROM size.

The on-chip ROM has a capacity of 4KB, spanning from 000H to FFFH. It is typically used to store the firmware or core program instructions of the microcontroller.

For further reading, you can explore the topic of semiconductor memory, including different types such as SRAM, DRAM, and Flash memory, which are widely used in embedded systems.