Tandy 1000 Programmer's Reference Guide

Chapter 5 I Device Drivers
The CLOCK Device
To allow for a real time clock board to be integrated into the
system for TIME and DATE, there
is a special device (deter-
mined by the attribute word) called the CLOCK device. The
CLOCK device defines and performs functions like any other
character device. Most functions will be: “set done bit, reset er-
ror bit, return.”
When
a read or write to this device occurs, exactly 6 bytes are
transferred. The
first two bytes are a word, which is the count of
days since 1-1-80. The third byte is minutes, the fourth hours,
the fifth 1/100 seconds, and the sixth seconds. Reading the
CLOCK device gets the date and time; writing to it sets the
date and time.
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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