Tandy 1000 Programmer's Reference Guide

Chapter 1 I System Calls
Curdsk
Current Disk Function Call 19H
Returns the code of the currently selected drive.
En try Conditions:
AH = 19H
E
xi t Conditions:
AL = currently selected drive (0 = A, 1 = B, etc.)
Macro Definition:
current-disk
macro
mov ah,l9H
int
21 H
endm
Example:
The following program displays the currently selected (default)
drive in a 2-drive system.
message db
crlf db
"Current disk 15 0" ;see Function 09H
1 3,l 0 , "0"
;for explanationof $
func-19H: display message ;see Function 09H
current-disk ;THIS FUNCTION
1 "e disk-b ;no, it's disk B
display-char "A" ;seeFunction 02H
JmP all-done
disk-b: d i sp 1 ay-c har "E"
;seeFunction 02H
all-done:
display crlf ;5eeFunction 09H
CmP al,00H ;I5 it disk A7
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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