Information storage apparatus

Abstract: An information storage apparatus for first-in-first-out storage and output of information comprising a plurality of storage cells, an input circuit for sequentially delivering information to the storage cells, and a control circuit for controlling the operation of the apparatus in response to at least one clocked signal. The storage cells are arranged to effect serial progression of information therethrough in a predetermined sequence to an output, all in response to the control circuit. The control circuit directs the information to the empty of the plurality of storage cells which is most proximate to the output of the apparatus by the input circuit which provides parallel inverse representations of the information to the storage cells.

Description: The present invention is directed to an information storage apparatus adaptable for first-in-first-out storage and output of information packets. In particular, the described embodiment is an information storage apparatus which is particularly amenable to implementation in large sizes without adding to propagation delay. Prior art storage devices effecting a first-in-first-out (FIFO) mode of operation, such as the device disclosed in U.S. Letters Patent No. 4,805,139, "Propagating FIFO Storage Device", issued to the same inventor and assigned to the same assignee as the present application, provide for input of information packets at a first cell in a plurality of cells making up the FIFO storage device. Clock signals control the propagation of information through the plurality of cells making up the FIFO storage device until the information packets reach the output of the device. Thus, by adding a greater capacity to the prior art devices, in the form of a greater number of storage cells, the propagation delay in passing information packets through the storage device is increased. US Patent No 4,156,288 discloses an asynchronous shift register with turnpike feature. A data source drives one of two leads negative to indicate that a binary one or zero is being written and gating circuitry enters the incoming bit of data into the stage of the shift register which is the empty stage nearest the output. Single bit data storage is provided by three cross-coupled 6-input gates. A control means, which detects the top of the stack of information packets within the storage cells, and an input means, which directs newly arriving information packets directly to the next available empty storage cell nearest the output of the device (i.e., to the top of the stack). Thus, the previously inherent trade-off of increased propagation time for increased storage capacity is eliminated. SUMMARY OF THE INVENTION The invention is defined in the appended claims. The input means provide parallel inverse representations of the information to the storage means. The input means are connected in a manner to avail such delivery of true representations of the information packets to even-numbered of the plurality of stored cells from the output, and are connected to avail such delivery of inverted representations of information packets to odd-numbered of the plurality of storage cells from the output. Preferably, the control means, for each respective storage cell of the plurality of storage cells, determines that the respective storage cell is empty and determines that the next preceding storage cell is not empty as prerequisite conditions to enabling serial progression of the information packet from the next preceding storage cell to the respective storage cell. Preferably, the control means, for each respective storage cell determines that the respective storage cell is empty, determines that the next preceding storage cell is empty, and determines that the next succeeding storage cell is not empty, thereby determining the top of the stack of information within the plurality of storage cells and, consequently, enabling delivery of a respective information packet to the respective storage cell. We will describe an information storage apparatus which is adaptable for first-in-first-out storage and output of information packets. We will describe an information storage apparatus which effects data input directly to the empty storage cell most proximate to the output of the storage apparatus. We will describe an information storage apparatus which can be increased in capacity in terms of numbers of storage cells, with no adverse impact in terms of increased propagation time of information through the storage apparatus. Further objects and features of the present invention will be apparent from the following specification and claims when considered in connection with the accompanying drawings illustrating the preferred embodiment of the invention. DETAILED DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram of an information storage apparatus according to the preferred embodiment of the present invention. Fig. 2, comprising Fig. 2A and Fig. 2B, is an electrical schematic diagram of an information storage apparatus according to the preferred embodiment of the present invention. Fig. 3 is a timing diagram illustrating various signals associated with writing information into the apparatus of the present invention. Fig. 4 is a timing diagram illustrating signals associated with propagating information through the apparatus of the present invention. DETAILED DESCRIPTION OF THE INVENTION In Fig. 1, an information storage apparatus 10 is illustrated in a schematic block diagram. Apparatus 10 is comprised of a plurality of storage cells 12, 14, 16, 18, 20. As indicated by dotted lines intermediate storage cell 16 and storage cell 18, additional storage cells may be interposed to provide an apparatus 10 of any number of storage cells. Each storage cell 12, 14, 16, 18, 20 is comprised of a plurality of byte cells and an associated with a storage cell 12, 14, 16, 18, 20 may vary according to the length of an information packet which may be desired to be stored within apparatus 10. For purposes of illustration, Fig. 1 illustrates an apparatus 10 having two byte cells per storage cell 12, 14, 16, 18, 20. Accordingly, storage cell 12 is comprised of tracking cell 22 and byte cells 24, 26; storage cell 16 is comprised of tracking cell 28 and byte cells 30, 32; storage cell 16 is comprised of tracking cell 34 and byte cells 36, 38; storage cell 18 is comprised of tracking cell 40 and byte cells 42, 44; and storage cell 20 is comprised of tracking cell 46 and byte cells 48, 50. Each tracking cell 22, 28, 34, 40, 46 is comprised of a logic module and a status module. Accordingly, tracking cell 22 includes logic module 52 and status module 54; tracking cell 28 includes logic module 56 and status module 58; tracking cell 34 includes logic module 60 and status module 62; tracking cell 40 includes logic module 64 and status module 66; and tracking cell 46 includes logic module 68 and status module 70. Input to respective storage cells 12, 14, 16, 18, 20 is effected through parallel input lines for each bit of information to respective byte cells 24, 26, 30, 32, 36, 38, 42, 44, 48, 50. Accordingly, byte 1 of information is provided by noninverted data input line DIN1 and by inverted data input line DIN1L. Preferably, inverted inputs provided by data input line DIN1L are applied to storage cells oddly numbered from the output of the apparatus 10 at data output lines DOUT1, DOUT2, and noninverted inputs are provided by data input line DIN1 to evenly numbered storage cells from the output of apparatus 10. Thus, in Fig. 1, inverted inputs are applied by inverted data input line DIN1L to storage cells 20 and 14, and noninverted inputs are provided to storage cells 18, 16, and 12 by data input line DIN1. Similarly, inverted data input DIN2L is applied to byte cell 50 of storage cell 20 and to byte cell 32 of storage cell 14; noninverted data input DIN2 is applied to byte cell 44 of storage cell 18, byte cell 38 of storage cell 16, and byte cell 26 of storage cell 12. Input to the various storage cells 12, 14, 16, 18, 20 is controlled by gates. Thus, noninverted data input line DIN1 is controlled by gates 72, 74, and 76; inverted data input line DIN1L is controlled by gates 78 and 80; noninverted data input line DIN2 is controlled by gates 82, 84, and 86; and inverted data input line DIN2L is controlled by gates 88 and 90. A WRITE signal is applied to logic module 52, 56, 60, 64, and 68 by WRITE lines 92, 94, 96, 98, and 100. Logic modules 52, 56, 60, 66, 68 all operate similarly and, thus, logic module 60 will be described as representative of the operation of all logic modules 52, 56, 60, 64, 68. Logic module 60 receives a WRITE signal from WRITE line 96. Logic module 60 also receives an indication of the status of storage cell 14 from status module 58 via line 102, receives status information as to the status of storage cell 18 from status module 66 via line 104, and receives status information regarding the status of storage cell 16 from status module 62 via line 106. When logic module 60 determines that storage cell 16 is empty, that storage cell 14 is empty, and that storage cell 18 contains information, then logic module 60 allows the WRITE signal to pass to parallel input line PIN3, thereby gating gate 74 and allowing data input DIN1 to pass information to byte cell 36. PIN3 also gates gate 84, thereby allowing data input line DIN2 to enter information in byte cell 38. Additionally, a gate 108 is gated allowing VCC to be applied to status module 62, thereby indicating that storage cell 16 is now full. In such manner, logic module 60 checks for the "top of the stack" of information packets within apparatus 10. In a similar manner, logic module 64 will check status module 62, status module 66, and status module 70 to ascertain whether storage cell 18 is the "top of the stack" of information packets within apparatus 10. Similarly, logic module 56 will check status module 54, status module 58, and status module 62 in determining whether storage cell 14 is the "top of the stack" of information packets within apparatus 10. Logic module 52, being associated with the topmost storage cell 12, needs only to check with status modules 54, 58 in determining whether storage cell 12 is the "top of the stack"; similarly, logic module 68 needs only to check status modules 70 and 66 to determine whether storage cell 20 is the "top of the stack" of information packets within apparatus 10. Each respective tracking cell 22, 28, 34, 40, 46, by its respective logic module 52, 56, 60, 64, 68 checking for "top of stack" location and controlling consequent gating of data input lines DIN1, DIN1L, DIN2, DIN2L (and any additional parallel inputs for additional bytes of information in an information packet -- not shown in Fig. 1) data may be input directly to the "top of the stack", i.e., directly to the empty storage cell most proximate the output of apparatus 10. A READ signal is applied to logic module 56 by READ line 110, to logic module 60 by READ line 112, to logic module 64 by READ line 114, and to logic module 68 by READ line 116. In controlling the READ function for propagating information packets from storage cell to storage cell within the apparatus 10, logic module 60 will check status module 58, via line 102, and will check status module 62, via line 106, to ascertain that storage cell 16 is empty and storage cell 14 contains information. When those two conditions are met, a READ signal is allowed to pass to serial input line SIN3. The READ signal on serial input line SIN3 gates a gate 118 to propagate information from byte cell 30 to byte cell 36, and gates a gate 120 to effect propagation of information from byte cell 32 to byte cell 38. Similarly, logic module 56 receives a READ signal from READ line 110 and, if status module 54 indicates that storage cell 12 is full and status module 58 indicates that storage cell 14 is empty, then logic module 56 allows the READ signal to pass to serial input line SIN2 which, in turn, gates gate 122 to enable propagation of information from byte cell 24 to byte cell 30, and gates gate 124 to enable propagation of information from byte cell 26 to byte cell 32. Likewise, logic module 64 receives the READ signal from READ line 114 and, if status module 62 indicates that storage cell 16 is full and status module 66 indicates that storage cell 18 is empty, then logic module 64 allows the READ signal to pass to serial input line SIN4. The READ signal then gates gate 126 to enable propagation of information from byte cell 36 to byte cell 42 and gates gate 128 to enable propagation of information from byte cell 38 to byte cell 44. Logic module 68 receives a READ signal from READ line 116 and, if status module 66 indicates that storage cell 18 is full and status module 70 indicates that storage cell 20 is empty, then logic module 68 gates the READ signal to serial input line SIN5 which enables gating of gate 130 to effect propagation of information from byte cell 42 to byte cell 48 and gates gate 132 to enable propagation of information from byte cell 44 to byte cell 50. Thus, during a READ operation, each respective logic module checks to ensure availability of its respective storage cell to receive information as well as checks that the next higher storage cell contains information to provide as prerequisite conditions to enabling propagation of information, byte-by-byte, from an upper storage cell to a lower storage cell. For purposes of ease of understanding of the invention, like elements will be identified by like reference numerals in the various figures. Fig. 2 is an electrical schematic diagram of the preferred embodiment of the present invention. In Fig. 2, a representative apparatus 10 is illustrated having storage cells 12, 14, 16, and 20. Each storage cell 12, 14, 16, 20 is comprised of a plurality of byte cells and an associated tracking cell. For purposes of illustration, two byte cells are shown for each storage cell 12, 14, 16, 20, but, as will be recognized by one skilled in the art, additional byte cells may be employed to accommodate larger information packets. Thus, storage cell 12 has byte cells 24 and 26 and associated tracking cell 22 which includes logic module 52 and status module 54. Storage cell 14 has byte cells 30, 32 and associated tracking cell 28 which includes logic module 56 and status module 58. Storage cell 16 has byte cells 36, 38 and an associated tracking cell 34 which includes logic module 60 and status module 62. Storage cell 20 has byte cells 48, 50 and an associated tracking cell 46 which includes logic module 68 and status module 70. Storage cell 12 is the first storage cell in the stack of apparatus 10 and, therefore, has a slightly different logic module 52 than do middle storage cells 14, 16. Similarly, storage cell 20, being the last storage cell in the stack of apparatus 10, has a different logic module 46 than the other storage cells 12, 14, 16. Referring to middle storage cells 14, 16, and initially by way of illustration specifically referring to storage cell 14, logic module 56 is seen to comprise a parallel input logic circuit including NAND gate 134, inverter 136, and gate 138. Similarly, associated with serial input line SIN2 is a NAND gate 140, an inverter 142 and a transmission gate 144. NAND gate 134 receives an input 146 which is operatively connected to status module 54, an input 148 which is operatively connected to status module 62, and an input 150 which is operatively connected to status module 58. If each of the inputs 146, 148, 150 is a logic level "1", thereby indicating that storage cell 12 is empty, that storage cell 14 is empty, and that storage cell 16 is not empty, then the output of NAND gate 136 goes low, is inverted by inverter 136, and effects gating of transmission gate 138 to allow parallel input signal PIN2 to pass through transmission gate 138. Parallel input signal PIN2 thus gates transmission gate 78 to enable inverted data input line DIN1L to enter information to byte cell 30, and gates transmission gate 88 to allow inverted data input DIN2L to enter information to byte cell 32. Additionally, transmission gate 152 is gated by parallel input signal PIN2 to apply VCC to status module 58 in order that status module 58 may accurately indicate that an information packet is stored in storage cell 14. Status module 58 includes a paired inverter storage cell 154 and, similarly, byte cell 30 is comprised of a paired inverter storage cell 156 and byte cell 32 is comprised of a paired inverter storage cell 158. In such manner, tracking cell 28, with its included logic module 56 and status module 58, detects the "top of the stack" of information within apparatus 10 and enables bytes of an information packet to go directly to the empty storage cell most proximate the output DOUT1, DOUT2 of apparatus 10, i.e., directly the "top of the stack" of information stored within apparatus 10. Serial input signal SIN2 is controlled by logic module 56, and in particular, by NAND gate 140 and its associated inverter 142 and transmission gate 144. NAND gate 140 receives an input 160 which is operatively connected to status module 58, and receives an input 162 which is operatively connected to status module 54. When both inputs 160, 162 are logic "1", thereby indicating that storage cell 12 contains information and storage cell 14 is empty, the output of NAND gate 140 goes low, is inverted by inverter 142, and gates transmission gate 144 to allow passage of serial input signal SIN2 to effect gating of gate 122 to enable propagation of information from byte cell 24 to byte cell 30, and also to gate transmission gate 124 to enable propagation of information from byte cell 26 to byte cell 32. Serial input signal SIN2 also effects gating of transmission gate 164 in order to pass the "full" status indicated by status module 54 to status module 58 and accurately indicate that an information packet had been passed from storage cell 12 to storage cell 14. In order to ensure clarity of understanding of Fig. 2, detailed identification of elements will not attempted. Given the detailed description of the preferred embodiment of the invention in connection with Fig. 1, and the correlation of box identifications between Fig. 1 and Fig. 2, along with the detailed description of operation of storage cell 14, one skilled in the art may readily understand the operation of the preferred embodiment of the present invention illustrated in Fig. 2. Fig. 3 is a timing diagram indicating the various signals associated with operation of the preferred embodiment of the present invention illustrated in Fig. 2. In Fig. 3, clock signals PH1, PH2 are synchronous clock signals having opposite phases. A WRITE signal is initiated whenever it is desired to write information packets to the byte cells of the apparatus 10. The WRITE signal is synchronized with clock signal PH1 and clock signal PH2 in that the WRITE signal is always initiated when clock signal PH1 goes positive (e.g., at times t 3 , t 7 , t 11 ) and WRITE signal goes to zero when clock signal PH2 goes to zero (e.g., at times t 5 , t 9 , t 13 ). Consequently, the WRITE PH2 signal is in phase with clock signal PH2, as indicated by the electrical schematic diagram of Fig. 2 as well as the timing diagram of Fig. 3. Signals BA1, BA2, BA3 respectively represent the outputs of status modules 54, 58, 62 in Fig. 2. Thus, as clearly illustrated in Fig. 3, the storage cells of the present invention fill from the bottom of the "stack" in that line BA3 goes positive before line BA2 goes positive which in turn occurs before line BA1 goes positive. Of course, as further illustrated in Fig. 3, parallel input signals are enabled by their respective tracking cells in order from the "bottom of the stack" so that parallel input signal PIN3 is enabled prior to enablement of parallel input signal PIN2 which, in turn, is enabled prior to parallel input signal PIN1. Thus, parallel input signal PIN3 affects the signal present on line BA3, parallel input signal PIN2 affects the signal present on line BA2,and parallel input signal PIN1 affects the signal level on line BA1. A timing diagram of the various signals associated with propagation of information through the various storage cells of the apparatus 10 is illustrated in Fig. 4. The propagation of information through apparatus 10 is dependent upon the same clock signals PH1, PH2. A READ signal, which is initiated coincident with a positive-going PH1 (e.g., at times t 1 , t 5 , t 9 ) and has a duration spanning PH1 and PH2, is applied to a NAND gate 166 which NAND gate 166 has as a second input clocking signal PH2. Thus, NAND gate 166 produces an output which, when inverted by inverter 168, is the READ PH2 signal illustrated in Fig. 4. The READ PH2 signal is applied to gate 170 in status module 70 and thereby zeroes the input node 172 of inverter pair 174. The next subsequent positive going clock signal PH1 gates transfer gate 176, thereby bringing line BA4 to zero and, because of inverter 178, applying a logic "1" input to NAND gate 180 in logic module 68. Thus, at such time, NAND gate 180 receives appropriate inputs to effect gating of gate 182 so that the next subsequent clocking signal PH2 passes through gate 182 to effect transfer of information stored in storage cell 16 in a manner previously described in connection with the operation of storage cell 14. By such use of two clocking signals PH1, PH2, the status module of a respective storage cell is assured to be cleared prior to the propagation of date from a next-higher cell in the "stack" to that respective storage cell.

Claims: An information storage apparatus (10) to store information packets and sequentially present said information packets at an output (DOUT1, DOUT2) on a first-in-first-out basis, the apparatus comprising: a storage means to store said information, said storage means comprising an array of storage cell means (12-20) for storing said information packets: an input means (DIN1, DINIL, DIN2, DIN2L) for delivering said information packets to said storage means; and a control means for controlling movement of said information packets within the apparatus in response to at least one clocked signal (PH2); said array of storage cell means (12-20) being configured for passing said information packets among said array of storage cell means in a predetermined sequence to an output in response to said control means; said control means enabling the receiving of said information packets, by the empty of said array of storage cell means most proximate to said output; and wherein said array of storage cell means (12-20) having a plurality of first storage cell means and a plurality of second storage cell means, one of said plurality of first storage cell means and said plurality of second storage cell means being operatively connected as odd-numbered storage cell means (20,14) from said output, the other of said plurality of first storage cell means and said plurality of second storage cell means being operatively connected as even-numbered storage cell means (18,16,12) from said output; and wherein said input means (DIN1, DINIL, DIN2, DIN2L) inputs said information packets to said plurality of second storage cell means and inputs an inverse representation of said information packets to said plurality of first storage cell means. An information storage apparatus (10) as claimed in Claim 1 wherein each respective storage cell means (12) of said array of storage cell means includes at least one byte cell (24,26). An information storage apparatus (10) as claimed in Claim 1 or Claim 2 wherein said array of storage cell means receives said information packets from said input means in response to a signal on a write input (WRITE) of said apparatus. An information storage apparatus (10) as claimed in any one of Claims 1 to 3 wherein said control means includes a plurality of status means (54,58,62,66,70) for registering a status for each storage cell means of said array of storage cell means and a plurality of logic means (52,56,60,64,68) for monitoring the status of each adjacent storage cell means of said array of storage cell means. An information storage apparatus (10) as claimed in Claim 4 wherein said control means comprises a dedicated status means (54) of said plurality of status means for each respective storage cell means (12) of said array of storage cell means, and wherein said control means comprises a dedicated logic means (52) of said plurality of logic means for each respective storage cell means (12) of said array of storage cell means. An information storage apparatus (10) as claimed in any one of Claims 1 to 5 wherein said control means enables the passing of said information packets only to an empty storage cell means of said array of storage cell means from an adjacent information-containing storage cell means of said array of storage cell means. An information storage apparatus (10) as claimed in any one of claims I to 6 wherein said control means. for each respective storage cell means of said array of storage cell means, ascertains that said respective storage cell means is empty, ascertains that the next preceding storage cell means of said array of storage cell means is empty or is not present, and ascertains that the next succeeding storage cell means of said array of storage cell means is not empty or is not present as prerequisite conditions to enabling said receiving of said information packets by said respective storage cell means. An information storage apparatus (10) as claimed in Claim 4 or Claim 5 wherein said logic means (56) comprises a first digital logic device (140). said first digital logic device producing a first logical output in response to status inputs from a storage cell means (14) and from a next preceding storage cell means (12) (if present); said first logical output gating a first line to allow a shift-gate signal (SIN2) to pass and shift gate means (122,124) for enabling serial progression from said next preceding storage means (12) (if present) to said storage cell means (14). An information storage apparatus (10) as claimed in Claim 7 wherein said ascertainments are effected by a second digital logic device (134), said second digital logic device producing a second logical output in response to ascertaining inputs from said respective storage cell means (14), from said next preceding storage cell means (12), and from said next succeeding storage cell means (16), said second logical output gating a second line to allow an input-gate signal (PIN2) to pass and gate said input means to enable said receiving of said information packets by said respective storage cell means (14).

Inventors: NORRIS DAVID, NORRIS, DAVID
Applicants: ADVANCED MICRO DEVICES INC, ADVANCED MICRO DEVICES, INC.
Application year: 1991
Main classification: G06F5
IPC codes: G06F5, G11C7