Fast ATA-compatible drive interface with error detection and/or error correction

In a computer system having a host processor, a peripheral device such as a hard disk drive and a data bus including data lines carrying data signals when said bus is active and high impedance signals when said bus is inactive, DMA request and acknowledge lines and a data strobe line carrying a periodic data strobe, an ATA-compatible method of implementing fast data transfers across said data bus between said host and said device, wherein said data transfer involves transferring a data block consisting of at least one data word, comprising the steps of:

• (a) said device asserting a DMA request on said DMA request line;
• (b) said host asserting a DMA acknowledge on said DMA acknowledge line in response to said DMA request;
• (c) activating said data strobe no earlier than a minimum setup time after the assertion of said DMA acknowledge, one data period of said data strobe consisting of alternating high and low strobe signals, said period having a duration of approximately 100 nanoseconds, said low and high strobe signals having a duration of no less than 40 nanoseconds;
• (d) a sender selected from said host or said device placing a first data word on said data bus no later than 20 nanoseconds before said data strobe begins a first transition from said low to said high strobe signal, removing said first data word after said first transition, and immediately thereafter placing a second data word on said data bus no later than 20 nanoseconds before said data strobe begins a second transition from said high to said low strobe signal;
• and
• (e) a receiver selected from the one of said host or said device not being said sender receiving said first and second data words from said data bus upon the occurrence, respectively, of said first and second transitions;
• said method resulting in a data transfer frequency across said data bus of approximately 40 MHz.

In an ATA device interface circuit responsive to external data signals, an external read strobe, an external write strobe, an external DMA acknowledge (DMA ACK) signal and an internal DMA request (DMA REQ) signal, wherein said device interface circuit includes a data bus, read and write pipeline registers, read and write FIFOs, a command decoder that generates a data transfer (DATA XFR) signal in response to a host data transfer command placed on said data bus, a transfer enable gate that generates a transfer enable (XFR ENA) signal when said DMA ACK and said DMA REQ signals are asserted, and read/write AND gates that generate read/write clock signals by ANDing said DATA XFR signal, XFR ENA signal and said external read/write strobes, said read pipeline register only being enabled for output to said data bus when said read clock signal is asserted, said write pipeline register inputting a data word from said data bus on every high to low transition of said write clock signal, the improvement comprising:

• fast-transfer-enabling circuitry driven by said write clock and read clock signals and connected to said write and read pipeline registers for enabling said write and read pipeline registers to input and output said data from and to said data bus on every edge of said write and read clock signals, respectively;
• command control logic with inputs tied to a status input from said first command decoder and said data bus, said command control logic asserting a READ COMMAND signal when solid first command decoder asserts said COAND/STATUS signal and continuing to assert said READ COMMAND as long as data transfer has not been finished;
• and
• a bus-enabling AND gate with two inputs tied respectively to said XFR ENA and said READ COMMAND signals, the output of said bus-enabling AND gate being an output enable (OE) signal that remains asserted as long as said data transfer is underway, said OE signal being tied to the output enable pin of said read pipeline register, thereby continually enabling said read pipeline register for output for low and high signal levels of said read clock signal.