_ The second bit is always '1'.

_ The last 4 bits specify code for data Length

_ Third field of 0 to 64 bits- Its length depends on the data length code in the control field. *

Fourth field (third if data field has no bit present) of 16 bits- CRC (Cyclic Redundancy

Check) bits.

* The receiver node uses it to detect the errors, if any, during the transmission

* Fifth field of 2 bits- First bit 'ACK slot'

* ACK = '1' and receiver sends back '0' in this slot when the receiver detects an error in the
reception.

* Sender after sensing '0' in the ACK slot generally retransmits the data frame.

* Second bit 'ACK delimiter’ bit. It signals the end of ACK field.

* If the transmitting node does not receive any acknowledgement of data frame within a specified
time slot, it should retransmit.

Sixth field of 7-bits - end- of- the frame specification and has seven '0's

2. B) SOFTWARE IN A SYSTEM

ROM image, Programming Languages and Program models

1. ROM Image
* Final stage software also called ROM image

(Just as an image is a unique sequence and arrangement of pixels, embedded software is also

a unique placement and arrangement at each ROM address of bytes for instructions and data.)