Browse Prior Art Database

Multilevel Display System

IP.com Disclosure Number: IPCOM000050764D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Baker, DC: AUTHOR [+3]

Abstract

A refresh buffer driving a 1K by 1K pel (picture element) display with 1 byte/pel requires 1M bytes of RAM (random access memory). This article shows a method of using less storage for applications which require some windows with fewer than 8 bits/pel. A multilevel display system refers to windows with multiple levels of color or gray scale.

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Multilevel Display System

A refresh buffer driving a 1K by 1K pel (picture element) display with 1 byte/pel requires 1M bytes of RAM (random access memory). This article shows a method of using less storage for applications which require some windows with fewer than 8 bits/pel. A multilevel display system refers to windows with multiple levels of color or gray scale.

Fig. 1A shows a screen with four windows labeled Wx where x is the number of bits/pel. Fig. 1B shows a refresh RAM 1 byte wide while is addressed from 0 to > 320K. The bytes for W2 contain 2 pixels/byte. The dimensions of W2 are 1K by 200, yielding 10K bytes of storage. The means of using the refresh buffer will now be described.

Fig. 2 shows a display system interfacing the display processor and the video look-up table (VLT). The display processor sends descriptions of the windows and storage locations in the refresh buffer to the switch. The switch is responsible for notifying each of the N controllers when it is to supply bytes to the VLT.

Fig. 3 shows the data needed for each controller to unpack pixels into bytes to the VLT. The current address is reset to the start address at the beginning of each new refresh cycle. The other registers are used to shift bits to form bytes for the VLT. The buffer which loads multiple bytes from the RAM feeds a shift register which shifts the required bits to form a byte to access the VLT.

Features - The size of the refresh buffer is reduced. - The display contro...