Tandy 1000 Programmer's Reference Guide

Appendix C
MS-DOS Memory Map
HEXADECIMAL
STARTING ADDRESS
(SEGMENT:OFFSET)
000:00
000:80
0040:00l
0050:00
0070:00
0190:002
05B0:002
X800:003
B800:004
F000:00
FC00:00
Notes:
xc00:003
DESCRIPTION
BIOS Interrupt Vectors
Available Interrupt vectors
ROM BIOS Data Area
MSDOS and BASIC Data Area
I/O.SYS Drivers
Available to user
Video RAM in
32K video modes
Video RAM in
16K video modes
Video RAM Window
(32K)
Reserved for system ROM
System BIOS ROM
MS-DOS
1. Detailed description in following pages.
2. Approximate address; subject to change.
3. “X” is defined as follows:
Memory Size X Value
128K
256K
384K
512K
640K
768K
4. Video memory accessed through the B800:0 window for all
video 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