Tandy 1000 Technical Reference Manual

Tandy 1000
Graphics Mode
Technical Reference Manual
The Video Color/Graphics System can be programmed for a wide variety of
modes. The Tandy 1000 and its system
ROM BIOS supports the following
Graphics Modes:
Mode
1MB PCjr IBM PC
4-Color Medium-Resolution x
x
16-Color Medium-Resolution x
16-Color Low-Resolution x
2-Color High-Resolution
x x
4-Color High Resolution x
Low and medium resolution modes work on
all types of display devices. The
high-resolution mode may require a monitor for correct operation.
Graphics Memory Usage
Graphics memory uses either two or four banks of 8000 bytes. In either case
pixel information for the display's upper-left corner
is found at address 0000.
The 4-color high-resolution and 16-color medium-resolution graphics use four
banks of 8000 bytes.
The following
is a table of the graphics storage organization for four banks
of 8000 bytes:
f--160 Bytes-j Memory
r----------, OOOOH
00 Scans (0, 4, 8, ... 196)
1F3FH
2000H
01 Scans (1, 5, 9, ... 197)
3F3FH
4000H
10 Scans
(2,6, 10, ... 198)
5F2FH
6000
11 Scans (3, 7, 11, ... 199)
7F3FH
Graphics Storage Organization
The 2-color high-resolution graphics, the 4-color medium-resolution graphics,
and the 16-color low-resolution graphics use only two banks of 8000 bytes.
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Tandy 1000 Specifications

General

Processor	Intel 8088
Processor Speed	4.77 MHz
RAM	128 KB (expandable to 640 KB)
Operating System	MS-DOS 2.11
Manufacturer	Tandy Corporation
Release Year	1984
Storage	Single or double 5.25" floppy disk drive (360 KB), optional hard drive
Sound	Tandy 3-voice sound
Ports	Parallel, Serial
Graphics	CGA (Color Graphics Adapter)
Graphics Modes	320x200, 640x200