Tandy 1000 Technical Reference Manual

Tandy 1000
Technical Reference Manual
Border Color Register
This 4-bit (write-only) register can be addressed in the video array at 02H. The
following table gives the register's bit functions.
Bit Description
o B (Blue) Border Color Select
1 G (Green) Border Color Select
2 R
(Red) Border Color Select
3 I
(I ntensity) Border Color Select
Border Color Register
The screen-border color is defined by bits 0-3, that selects one of 16 colors.
See the Colors Definition Table listed in this section.
Mode Control Register
This 5-bit (write-only) register is accessed at the video array address 03H. The
following table gives the register's bit functions.
Bit Description
o Not used
1 Not used
2 Border Enable
3 4 Color High
Res.
4 16 Color Mode
Mode Control Register
Bit 0 Not Used
Bit 1 Not Used
Bit 2 This bit enables the border color register. For PC compatibility this
bit should be
O. For PCjr compatibility this bit should be 1.
Bit 3 For the 4 color 640 x 200 graphics mode, this bit should be set to
1 and for
all other modes set to O.
Bit 4 Set this bit to 1 for 16 color modes and to 0 for all other modes.
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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