L 67201/L 67202
MATRA MHS
Table 1 : Reset and retransmit
Single Device Configuration/Width Expansion Mode
INPUTS
INTERNAL STATUS
Read Pointer Write Pointer
OUTPUTS
MODE
RS
0
RT
X
XI
0
EF
0
FF
1
HF
1
Reset
Location Zero
Location Zero
Location Zero
Unchanged
Retransmit
Read/Write
1
0
0
X
X
X
(4)
(4)
1
1
0
Increment
Increment
X
X
X
Note : 4. Pointer will increment if flag is high.
Table 2 : Reset and First Load Truth Table
Depth Expansion/Compound Expansion Mode
INPUTS
INTERNAL STATUS
OUTPUTS
MODE
RS
0
FL
0
XI
(5)
(5)
(5)
Read Pointer
Write Pointer
Location Zero
Location Zero
X
EF
FF
1
Reset First Device
Reset All Other Devices
Read/Write
Location Zero
Location Zero
X
0
0
0
1
1
1
X
X
X
Note : 5. XI is connected to XO of previous device.
See fig. 5.
Depth Expansion (Daisy Chain) Mode
Compound Expansion Module
It is quite simple to apply the two expansion techniques
described above together to create large FIFO arrays (see
figure 5).
The L 67201/202 can be easily adapted for applications
which require more than 512/1024 words. Figure 4
demonstrates Depth Expansion using three L 67201/202.
Any depth can be achieved by adding additional
67201/202.
Bidirectional Mode
The L 67201/202 operate in the Depth Expansion
configuration if the following conditions are met :
Applications which require data buffering between two
systems (each system being capable of Read and Write
operations) can be created by coupling L 67201/202 as
shown in figure 6. Care must be taken to ensure that the
appropriate flag is monitored by each system (i.e. FF is
monitored on the device on which W is in use ; EF is
monitored on the device on which R is in use). Both Depth
Expansion and Width Expansion may be used in this
mode.
1. The first device must be designated by connecting the
First Load (FL) control input to ground.
2. All other devices must have FL in the high state.
3. The Expansion Out (XO) pin of each device must be
connected to the Expansion In (XI) pin of the next
device. See figure 4.
4. External logic is needed to generate a composite Full
Flag (FF) and Empty Flag (EF). This requires that all
EF’s and all FFs be ØRed (i.e. all must be set to
generate the correct composite FF or EF). See figure 4.
Data Flow - Through Modes
Two types of flow-through modes are permitted : a read
5. The Retransmit (RT) function and Half-Full Flag (HF) flow-through and a write flow-through mode. In the read
are not available in the Depth Expansion Mode. flow-through mode (figure 17) the FIFO stack allows a
6
Rev. C (10/11/95)
TEMIC [ TEMIC SEMICONDUCTORS ]
