Data bus protocol for computer graphics system

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus having n bits, apparatus for transferring data between said circuit blocks, comprising:

• a circuit in the first circuit block for sequentially transmitting data words from the first circuit block to the second circuit block on said data bus, said data words including one or more long data words having more than n bits;
• a register in the first circuit block for storing bits of said long data words in excess of n bits;
• a controller in the first circuit block, responsive to transmission of said long date words, for loading the bits of said long data words in excess of n bits into said register, and for combining the bits of said long data words stored in said register into a composite data word for transmission to said second circuit block;
• a circuit in the second circuit block for reassembling said long data words;
• and
• wherein the data words further include a short data word having less than n bits, and wherein the controller is responsive to transmission of said short data words for combining the bits of said long data words stored in said register with said short data word to form the composite data word for transmission to said second circuit block.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus having n bits, apparatus for transferring data between said circuit blocks, comprising:

• a circuit in the first circuit block for sequentially transmitting data words from the first circuit block to the second circuit block on said data bus, said data words including one or more long data words having more than n bits;
• a register in the first circuit block for storing bits of said long data words in excess of n bits;
• a controller in the first circuit block, responsive to transmission of said long data words, for loading the bits of said long data words in excess of n bits into said register, and for combining the bits of said long data words stored in said register into a composite data word for transmission to said second circuit block;
• and
• wherein the data words include a short data word having less than n bits, and wherein the controller is responsive to transmission of said short data words for combining the bits of said long data words stored in said register with said short data word to form the composite data word for transmission to said second circuit block.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus having n bits, apparatus for transferring data between said circuit blocks, comprising:

• a circuit in the first circuit block for sequentially transmitting data words from the first circuit block to the second circuit block on said data bus, said data words including one or more long data words having more than n bits;
• a register in the first circuit block for storing bits of said long data words in excess of n bits;
• a controller in the first circuit block, responsive to transmission of said long data words, for loading the bits of said long data words in excess of n bits into said register, and for combining the bits of said long data words stored in said register into a composite data word for transmission to said second circuit block;
• and
• wherein the controller includes means for deleting a sufficient number of the bits of said long data words to reduce the number of bits of said composite data word to n bits.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus for transmitting data as words having n bits, a method of transferring data words over the data bus comprising the steps of:

• transmitting n bits of each of the data words over the data bus from the first circuit block to the second circuit block, said data words including a plurality of long data words having more than n bits;
• storing bits of the long data words in excess of n bits in a register;
• combining the bits of the long data words in excess of n bits to form a composite data word having bits from at least two of the long data words;
• and
• transmitting the composite data word from the first circuit block to the second circuit block on the data bus.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus for transmitting data as words having n bits, a method of transferring data words over the data bus comprising the steps of:

• transmitting n bits of each of the data words over the data bus from the first circuit block to the second circuit block, said data words including one or more long data words having more than n bits;
• storing bits of the long data words in excess of n bits in a register;
• combining the bits of the long data words in excess of n bits to form a composite data word;
• transmitting the composite data word from the first circuit block to the second circuit block on the data bus;
• reassembling the long data words at the second circuit block;
• and
• wherein the data words further include a short data word having less than n bits and wherein the step of combining includes a step of combining the short data word with the bits of the long data words in excess of n bits to form the composite data word.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus for transmitting data as words having n bits, a method of transferring data words over the data bus comprising the steps of:

• transmitting n bits of each of the data words over the data bus from the first circuit block to the second circuit block, said data words including one or more long data words having more than n bits;
• storing bits of the long data words in excess of n bits in a register;
• combining the bits of the long data words in excess of n bits to form a composite data word;
• transmitting the composite data word from the first circuit block to the second circuit block on the data bus;
• and
• wherein the data words further include a short data word having less than n bits and wherein the step of combining includes a step of combining the short data word with the bits of the long data words in excess of n bits to form the composite data word.

In a computer graphics system comprising first and second circuit blocks interconnected by a data bus for transmitting data as words having n bits, a method of transferring data words over the data bus comprising the steps of:

• transmitting n bits of each of the data words over the data bus from the first circuit block to the second circuit block, said data words including one or more long data words having more than n bits;
• storing bits of the long data words in excess of n bits in a register;
• combining the bits of the long data in excess of n bits to form a composite data word;
• transmitting the composite data word from the first circuit block to the second circuit block on the data bus;
• and
• deleting a sufficient number of bits of the long data words to reduce the number of bits of the composite data word to n bits.