Tandy 1000 Technical Reference Manual

Tandy 1000
System Logic Registers
Video Array Registers
Technical Reference Manual
The Video Array is addressed at I/O addresses 308, 309, 30A, and 30E.
Address
308 and 309 are PC compatible control registers. Address 30A is
an address register for port selection inside the Video Array. Address 30E is
the data port. You can program all Video Array registers, except 308 and 309.
Registers are programmed by first writing an address to 30A and the data
to 30E.
The following chart shows the address at each of these Video Array
registers.
Register
Palette Mask
Border Color
Mode Control
Palette Registers
Address Hex
01
02
03
10 - 1F
Palette Mask Register
This 4-bit (write-only) register has a video array address of 01 H. The following
table lists each bit.
Bit
o
1
2
3
Palette Mask
o
1
2
3
This register allows any of the address lines into the palette where they are
then forced to
O.
50

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