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Part: 9403APC
Category:
Description: First-in First-out (FIFO) Buffer Memory
Company: Fairchild Semiconductor
Datasheet: Download 9403APC datasheet File size : 85 kB
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9403A First-In First-Out (FIFO) Buffer Memory
April 1989 Revised October 2000
9403A First-In First-Out (FIFO) Buffer Memory
General Description
The 9403A is an expandable fall-through type high-speed First-In First-Out (FIFO) Buffer Memory optimized for high speed disk or tape controllers and communication buffer applications. It is organized as 16-words by 4-bits and may be expanded to any number of words or any number of bits in multiples of four. Data may be entered or extracted asynchronously in serial or parallel, allowing economical implementation of buffer memories. The 9403A has 3-STATE outputs which provide added versatility and is fully compatible with all TTL families.
Features
s Serial or parallel input s Serial or parallel output s Expandable without external logic s 3-STATE outputs s Fully compatible with all TTL families s Slim 24-pin package
Ordering Code:
Order Number 9403APC Package Number N24E Package Description 24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-010, 0.400 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Logic Symbol
Connection Diagram
Š 2000 Fairchild Semiconductor Corporation
DS010193
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9403A
Unit Loading/Fan Out
U.L . Pin Names D0 D8 DS PL CPSI IES TTS O ES TOS TOP MR OE CPSO Q0 - Q3 QS I RF O RE Description HIGH/LOW Parallel Data Inputs Serial Data Input Parallel Load Input Serial Input Clock Serial Input Enable Transfer to Stack Input Serial Output Enable Transfer Out Serial Transfer Out Parallel Master Reset Output Enable Serial Output Clock Parallel Data Outputs Serial Data Output Input Register Full Output Register Empty 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 2.0/0.667 285/26.7 285/26.7 20/13.3 20/13.3 Input IIH/IIL Output IOH/IOL 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 40 ľA/400 ľA 5.7 mA/16 mA 5.7 mA/16 mA
-400 ľA/8 mA -400 ľA/8 mA
Block Diagram
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9403A
Functional Description
As shown in the block diagram the 49403A consists of three sections: 1. An Input Register with parallel and serial data inputs as well as control inputs and outputs for input handshaking and expansion. 2. A 4-bit wide, 14-word deep fall-through stack with selfcontained control logic. 3. An Output Register with parallel and serial data outputs as well as control inputs and outputs for output handshaking and expansion. Since these three sections operate asynchronously and almost independently, they will be described separately below. INPUT REGISTER (DATA ENTRY) The Input Register can receive data in either bit-serial or in 4-bit parallel form. It stores this data until it is sent to the fall-through stack and generates the necessary status and control signals. Figure 1 is a conceptual logic diagram of the input section. As described later, this 5-bit register is initialized by setting the F3 flip-flop and resetting the other flip-flops. The Q output of the last flip-flop (FC) is brought out as the "Input Register Full" output (IRF). After initialization this output is HIG H . Parallel Entry--A HIGH on the PL input loads the D0-D3 inputs into the F0-F3 flip-flops and sets the FC flip-flop. This forces the IRF output LOW indicating that the input register is full. During parallel entry, the CPSI input must be LOW. If parallel expansion is not being implemented, IES must be LOW to establish row mastership (see Expansion section). Serial Entry--Data on the DS input is serially entered into the F3, F2, F1, F0, FC shift register on each HIGH-to-LOW transition of the CPSI clock input, provided IES and PL are LOW. After the fourth clock transition, the four data bits are located in the four flip-flops, F0-F3. The FC flip-flop is set, forcing the IRF output LOW and internally inhibiting CPSI clock pulses from affecting the register, Figure 2 illustrates the final positions in a 9403A resulting from a 64-bit serial bit train. B0 is the first bit, B63 the last bit.
FIGURE 1. Conceptual Input Section
FIGURE 2. Final Positions in a 9403A Resulting from a 64-Bit Serial Train
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9403A
Functional Description
(Continued) Transfer to the Stack--The outputs of Flip-Flops F0-F3 feed the stack. A LOW level on the TTS input initiates a "fall-through" action. If the top location of the stack is empty, data is loaded into the stack and the input register is re-initialized. Note that this initialization is postponed until PL is LOW again. Thus, automatic FIFO action is achieved by connecting the IRF output to the TTS input. An RS Flip-Flop (the Request Initialization Flip-Flop shown in Figure 10) in the control section records the fact that data has been transferred to the stack. This prevents multiple entry of the same word into the stack despite the fact the IRF and TTS may still be LOW. The Request Initialization Flip-Flop is not cleared until PL goes LOW. Once in the
stack, data falls through the stack automatically, pausing only when it is necessary to wait for an empty next location. In the 9403A as in most modern FIFO designs, the MR input only initializes the stack control section and does not clear the data. OUTPUT REGISTER (DATA EXTRACTION) The Output Register receives 4-bit data words from the bottom stack location, stores it and outputs data on a 3-STATE 4-bit parallel data bus or on a 3-STATE serial data bus. The output section generates and receives the necessary status and control signals. Figure 3 is a conceptual logic diagram of the output section.
FIGURE 3. Conceptual Output Section Parallel Data Extraction--When the FIFO is empty after a LOW pulse is applied to MR, the Output Register Empty (ORE) output is LOW. After data has been entered into the FIFO and has fallen through to the bottom stack location, it is transferred into the Output Register provided the "Transfer Out Parallel" (TOP) input is HIGH. As a result of the data transfer ORE goes HIGH, indicating valid data on the data outputs (provided the 3-STATE buffer is enabled). TOP can now be used to clock out the next word. When TOP goes LOW, ORE will go LOW indicating that the output data has been extracted, but the data itself remains on the output bus until the next HIGH level at TOP permits the transfer of the next word (if available) into the Output Register. During parallel data extraction CPSO should be LOW. TOS should be grounded for single slice operation or connected to the appropriate ORE for expanded operation (see Expansion section). TOP is not edge triggered. Therefore, if TOP goes HIGH before data is available from the stack, but data does become available before TOP goes LOW again, that data will be transferred into the Output Register. However, internal control circuitry prevents the same data from being transferred twice. If TOP goes HIGH and returns to LOW before data is available from the stack, ORE remains LOW indicating that there is no valid data at the outputs. Serial Data Extraction--When the FIFO is empty after a LOW pulse is applied to MR, the Output Register Empty (ORE) output is LOW. After data has been entered into the FIFO and has fallen through to the bottom stack location, it is transferred into the Output Register provided TOS is LOW and TOP is HIGH. As a result of the data transfer ORE goes HIGH indicating valid data in the register. The 3-STATE Serial Data Output, QS, is automatically enabled and puts the first data bit on the output bus. Data is serially shifted out on the HIGH-to-LOW transition of CPSO. To prevent false shifting, CPSO should be LOW when the new word is being loaded into the Output Register. The fourth transition empties the shift register, forces ORE output LOW and disables the serial output, QS (refer to Figure 3). For serial operation the ORE output may be tied to the TOS input, requesting a new word from the stack as soon as the previous one has been shifted out.
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9403A
Functional Description
EXPANSION
(Continued) Horizontal and Vertical Expansion--The 9403A can be expanded in both the horizontal and vertical directions without any external parts and without sacrificing any of its FIFO's flexibility for serial/parallel input and output. The interconnections necessary to form a 31-word by 16-bit FIFO are shown in Figure 6. Using the same technique, any FIFO of (15m + 1)-words by (4n)-bits can be constructed, where m is the number of devices in a column and n is the number of devices in a row. Figure 7 and Figure 8 show the timing diagrams for serial data entry and extraction for the 31-word by 16-bit FIFO shown in Figure 6. The final position of data after serial insertion of 496 bits into the FIFO array of Figure 6 is shown in Figure 9. Interlocking Circuitry--Most conventual FIFO designs provide status signals analogous to IRF and ORE. However, when these devices are operated in arrays, variations in unit to unit operating speed require external gating to assure all devices have completed an operation. The 9403A incorporates simple but effective "master/slave" interlocking circuitry to eliminate the need for external gating. In the 9403A array of Figure 6 devices 1 and 5 are defined as "row masters" and the other devices are slaves to the master in their row. No slave in a given row will initialize its Input Register until it has received LOW on its IES input from a row master or a slave of higher priority. In a similar fashion, the ORE outputs of slaves will not go HIGH until their OES inputs have gone HIGH. This interlocking scheme ensures that new input data may be accepted by the array when the IRF output of the final slave in that row goes HIGH and that output data for the array may be extracted when the ORE of the final slave in the output row goes HIGH. The row master is established by connecting its IES input to ground while a slave receives it IES input from the IRF output of the next higher priority device. When an array of 9403A FIFOs is initialized with a LOW on the MR inputs of all devices, the IRF outputs of all devices will be HIGH. Thus, only the row master receives a LOW on the IES input during initialization. Figure 10 is a conceptual logic diagram of the internal circuitry which determines master/slave operation. Whenever MR and IES are LOW, the Master Latch is set. Whenever TTS goes LOW the Request Initialization Flip-Flop will be set. If the Master Latch is HIGH, the input Register will be immediately initialized and the Request Initialization Flip-Flop reset. If the Master Latch is reset, the Input Register is not initialized until IES goes LOW. In array operation, activating the TTS initiates a ripple input register initialization from the row master to the last slave. A similar operation takes place for the output register. Either a TOS or TOP input initiates a load-from-stack operation and sets the ORE Request Flip-Flop. If the Master Latch is set, the last Output Register Flip-Flop is set and ORE goes HIGH. If the Master latch is reset, the ORE output will be LOW until an OES input is received.
Vertical Expansion--The 9403A may be vertically expanded to store more words without external parts. The interconnection is necessary to form a 46-word by 4-bit FIFO are shown in Figure 4. Using the same technique, and FIFO of (15n + 1)-words by 4-bits can be constructed, where n is the number of devices. Note that expansion does not sacrifice any of the 9403A's flexibility for serial/ parallel input and output.
FIGURE 4. A Vertical Expansion Scheme Horizontal Expansion--The 9403A can also be horizontally expanded to store long words (in multiples of four bits) without external logic. The interconnections necessary to form a 16-word by 12-bit FIFO are shown in Figure 5. Using the same technique, any FIFO of 16 words by 4n bits can be constructed, where n is the number of devices. The IRF output of the right most device (most significant device) is connected to the TTS inputs of all devices. Similarly, the ORE output of the most significant device is connected to the TOS inputs of all devices. As in the vertical expansion scheme, horizontal expansion does not sacrifice any of the 9403A's flexibility for serial/parallel input and output.
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