Tandy 1000 Programmer's Reference Guide

Chapter 2 I MS-DOS Control Blocks and Work Areas
Program Segment Prefix
Following is an illustration of the Program Segment Prefix. Pro-
grams must not alter any part of the
PSP below offset 5CH.
OOH
08H
10H
2CH
5CH
6CH
80H
Environmental pointer
Used by MS-DOS
Formatted Parameter Area
1
formatted as standard unopened FCB
Formatted Parameter Area 2
formatted
as standard unopened FCB
(overlaid if FCB
at 5CH is opened)
Unformatted Parameter Area
(default Disk Transfer Area)
157
INT 20 H
End of
Long call to
allocation Reserved
MS-DOS functior
block
dispatcher
(5
Terminate address CONTROL-C exi
(IP,CS) address (IP)
bytes)
CONTROL-C
Exit address
(CS)
Hard error exit address
(IP,CS)

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