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Display Control Apparatus

IP.com Disclosure Number: IPCOM000038352D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 3 page(s) / 82K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR [+3]

Abstract

This article describes a display control apparatus which includes a scan code buffer and an all-points-addressable (APA) buffer. The APA buffer operates as a character generator for storing character patterns in text mode, and operates as a buffer for storing data bits supplied from a data source in APA mode. The scan code buffer stores character codes to access the character patterns in the APA buffer in the text mode, and stores control information to fetch the data bits from the APA buffer in the APA mode. Referring to Fig. 1, a scan code buffer 1, an attribute buffer 2, and an APA buffer 3 are divided into a plurality of small blocks. Each small block contains 32 x 32 bits in the APA mode. A microprocessor (not shown) controls the operation of the circuit blocks in Fig. 1.

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Display Control Apparatus

This article describes a display control apparatus which includes a scan code buffer and an all-points-addressable (APA) buffer. The APA buffer operates as a character generator for storing character patterns in text mode, and operates as a buffer for storing data bits supplied from a data source in APA mode. The scan code buffer stores character codes to access the character patterns in the APA buffer in the text mode, and stores control information to fetch the data bits from the APA buffer in the APA mode. Referring to Fig. 1, a scan code buffer 1, an attribute buffer 2, and an APA buffer 3 are divided into a plurality of small blocks. Each small block contains 32 x 32 bits in the APA mode. A microprocessor (not shown) controls the operation of the circuit blocks in Fig. 1. In the text mode, the character codes representing a text document to be displayed on a display unit 6 are supplied to the scan code buffer 1. One character code is stored in one block of the scan code

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buffer 1. Attribute codes for the character codes are supplied to the attribute buffer 2. The APA buffer 3 operates as a character generator in the text mode; hence, at the start of the text mode, character patterns are loaded into the APA buffer 3. The character codes stored in the scan code buffer 1 are used as addresses to access the character patterns in the APA buffer 3. The addressed character pattern is supplied to video control unit 5 through a parallel-serial converter 4. The attribute code for each character code is supplied to the video control unit 5 which controls the attribute of the displayed character pattern on the display unit 6. In the APA mode, the APA buffer 3 operates as a buffer for storing data bits supplied from a memory (not shown). The scan code buffer is supplied with control information. Each control information is stored in each block of the scan code buffer 1, and is used to transfer each data bit in each block in the APA buffer 3. The next table shows the control information #0 through #33 stored in the blocks #0 through #33 of the scan code buffer 1 and used for reading out the data bits of the blocks #0 t...