8

IDT72V281/72V291

Number of

Words in

FIFO

0

0

(n+1) to 32,768

32,769 to (65,536-(m+1))

65,536

72V281

72V291

FF PAF HF PAE EF

HH

HL

L

HH

HL

H

HH

H

H

H

HH

L

H

H

HL

L

H

H

LL

LH

H

4513 drw 05

0

0

(n+2) to 65,537

65,538 to (131,073-(m+1))

(131,073-m)

(2)

to 131,072

131,073

IR PAF HF PAE OR

LH

H

L

H

LH

H

L

L

L

H

HHL

LH

L

H

L

LLL

H

L

HL

L

H

L

72V281

72V291

Number of

Words in

FIFO

(n+1) to 65,536

65,537 to (131,072-(m+1))

131,072

(n+2) to 32,769

32,770 to (65,537-(m+1))

(65,537-m)

(2)

to 65,536

65,537

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

In addition to loading offset values into the FIFO, it also possible to read the

current offset values. It is only possible to read offset values via parallel read.

Figure 4, Programmable Flag Offset Programming Sequence, summa-

rizes the control pins and sequence for both serial and parallel programming

modes. For a more detailed description, see discussion that follows.

The offset registers may be programmed (and reprogrammed) any time

after Master Reset, regardless of whether serial or parallel programming

has been selected.

TABLE 1  STATUS .LAGS .OR IDT STANDARD MODE

TABLE 2  STATUS .LAGS .OR .W.T MODE