NEC UPD98413 User Manual page 60

(c) Inserting an idle cell
If the ATM device does not transmit cell data to the µ PD98413 and one cell of data is missing from the transmit
FIFO, a vacant (idle) cell is generated and inserted between data cells. The format of the inserted cell can be
changed to the unassigned cell format by using the IVCM bit of the MDATMT register. Figure3-16 shows the
formats of the idle cell and unassigned cell generated by the µ PD98413.
Idle cell
Unassigned cell
(d) Scramble of ATM cell
The data of an ATM cell is scrambled by using the following polynomial. The range of scramble is limited to the
48-byte payload of the ATM cell.
43
Polynomial G (X) = X
The user can select a scramble stop mode for the purpose of testing. The scramble stop mode is set by the
CSCM bit of MDATMT register.
60
CHAPTER 3 FUNCTIONAL OUTLINE
Figure 3-16. Format of Vacant Cell Inserted by
Hea
1 2 3
00H 00H 00H
00H 00H 00H
+ 1
PRELIMINARY
µ µ µ µ
PD98413
Payload: 48 bytes
4 5 1 2
01H 52H 6AH 6AH
00H 55H 00H 00H
47 48
6AH 6AH
00H 00H
NEC confidential and Proprietary