Shared bit-plane display system

• US 5,029,111 A
• Filed: 04/29/1987
• Issued: 07/02/1991
• Est. Priority Date: 04/29/1987
• Status: Expired due to Fees

• Current Assignee: Prime Computer, Inc. (DR Holdings, Inc. of Delaware)
• Original Assignee: Prime Computer, Inc. (DR Holdings, Inc. of Delaware)
• Inventors: Mansell, Barry N.
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): Nguyen, Phu K.
• Application Number:
  US07/043,705
• Time in Patent Office: 1,525 Days
• Field of Search: 364/521, 364/522, 364/238, 364/260.7, 364/134, 364/942.1, 340/799, 340/798, 340/750, 340/825.07, 340/825.08, 340/802, 370/61, 370/77, 455/3
• US Class Current: 345/550
• CPC Class Codes: G06F 3/1423 controlling a plurality of local displays, e.g. CRT and flat panel display
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence

Abstract

A multiuser display system in which the bit planes are shared by a plurality of user stations. A bus carries a superpixel containing bits from each of the bit planes in this system. Each user station is assigned particular bit planes and extracts the bits corresponding to the assigned bit planes from the superpixel. Double buffering within a window is made possible by providing two sets of bit plane identification registers.

Claims

1. A display system for a plurality of user stations comprising:

memory means for storing a plurality of bit planes;

means for retrieving a superpixel from said bit planes, said superpixel comprising a bit from the same pixel location in each bit plane of said plurality of bit planes; and

switching means associated with each user station for receiving said superpixel and for providing its associated user station with a data word, each switching means having first bit plane identification means for identifying which one or more of said plurality of bit planes is assigned to the associated user station such that said data word is comprised of the bits in said superpixel from said one or more bit planes assigned to said associated user station.

2. The display system of claim 1 wherein at least one of said switching means further comprises a second bit plane identification means for identifying a second one or more of said plurality of bit planes which is assigned to the associated user station and window selector means for selecting one of said first or second bit plane identification means for use by said switching means in determining said data word.

3. The display system of claim 2 wherein said window selector means reads a bit plane from said memory means, said bit plane determining the selection of said first or second bit plane identification means.

4. The display system of claim 1 further comprising a high speed data bus for transporting said superpixel from said retrieving means and interface means for removing said superpixel from said data bus and providing it to each of said switching means.

5. The display system of claim 4 wherein four superpixels are transported over said data bus at one time and each of said switching means provides four data words extracted from said four superpixels.

6. The display system of claim 1 wherein the number of bit planes in said plurality of bit planes is less than the product obtained by multiplying the number of user stations times the largest number of bit planes assigned to any one of said user stations.

7. The display system of claim 1 wherein said switching means comprises two switches, each switch receiving a different half of each superpixel.

8. The display system of claim 7 wherein said switching means have enable output registers, one associated with each of said two switches, said two enable output registers operating so that no more than one is enabled at a time for each output bit plane.

9. A method for sharing bit planes among a plurality of user stations comprising:

transmitting a plurality of superpixels each containing a bit from the same pixel location in each bit plane of a plurality of bit planes;

assigning a first set of bit planes from among said plurality of bit planes to each user station; and

extracting for each user station the bits assigned to said user station from each of said superpixels.

10. The method of claim 9 further comprising the steps of:

assigning a second set of bit planes to at least one of said user stations, and

selecting one of said first and second sets of bit planes for said at least one of said user stations before said step of extracting bits.

11. The method of claim 9 further comprising the steps of:

assigning a second set of bit planes to at least one of said user stations, and

switching between said first set of bit planes and said second set of bit planes in the middle of performing said step of extracting bits so as to display a window at said at least one of said user stations.