L 67203/L 67204
Table 1 : Reset and retransmit
Single Device Configuration/Width Expansion Mode
INPUTS
MODE
RS
Reset
Retransmit
Read/Write
0
1
1
MATRA MHS
INTERNAL STATUS
XI
0
0
0
OUTPUTS
EF
0
X
X
RT
X
0
1
Read Pointer
Location Zero
Location Zero
Increment
(4)
Write Pointer
Location Zero
Unchanged
Increment
(4)
FF
1
X
X
HF
1
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
MODE
RS
Reset First Device
Reset All Other Devices
Read/Write
0
0
1
INTERNAL STATUS
XI
(5)
(5)
(5)
OUTPUTS
EF
0
0
X
FL
0
1
X
Read Pointer
Location Zero
Location Zero
X
Write Pointer
Location Zero
Location Zero
X
FF
1
1
X
Note :
5. XI is connected to XO of previous device.
See fig. 5.
Depth Expansion (Daisy Chain) Mode
The L 67203/204 can be easily adapted for applications
which require more than 2048/4096 words. Figure 4
demonstrates
Depth
Expansion
using
three
L 67203/204s. Any depth can be achieved by adding
additional 67203/204.
The L 67203/204 operate in the Depth Expansion
configuration if the following conditions are met :
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.
5. The Retransmit (RT) function and Half-Full Flag (HF)
are not available in the Depth Expansion 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).
Bidirectional Mode
Applications which require data buffering between two
systems (each system being capable of Read and Write
operations) can be created by coupling L 67203/204 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.
Data Flow - Through Modes
Two types of flow-through modes are permitted : a read
flow-through and a write flow-through mode. In the read
flow-through mode (figure 17) the FIFO stack allows a
6
Rev. C (10/11/94)
TEMIC [ TEMIC SEMICONDUCTORS ]
