Tandy 1000 Technical Reference Manual

Tandy 1000
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Symbol
Pin No. Type
Vee
28
I
GND 14
CS
WA
0
AD
0-,-00
4-11
liD
CASo-CAS2
12,13,15 liD
SP/EN 16 liD
INT 17
0
IAO-IA]
18-25
INTA
26
Ao
27
Technical Reference Manual
8259AJ8259A-2/8259A-8
Table 1. Pin Description
Neme end Function
Supply: +5V Supply
Ground.
Bldlrectlonel De.e S",.: Control, status and interrupt-vector Information is transferred via thiS bus
Cueede Llnee: The CAS lines form a private 8259A bus to control a multiple 8259Astructure These
pins are oulputs for a master 8259A and inputs for a slave 8259A.
Sieve Progrem/Eneble Bulfer: ThiS IS a dual funclion pin. When In the Buffered Mode It can be used
as an output to control buffer transceivers (EN). When not in the buffered mode it is used as an Input
to designate a master (SP = 1) or slave (SP = 01
Interrupt: This pin goes high whenever a valid interrupt request is asserted. It is used'to interrupt the
CPU, thus it is connected to the CPU's Interrupt pin
AO Addreee Line: ThiS pin acts in conjunction with the CS, WA, and AD pins It IS used by the 8259A
to decipher various Command Words the CPU writes and status the CPU Wishes to read. It IS typically
connected to the CPU AO address line (A1 for iAPX 86,88).
2-121

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