Tandy 1000 Technical Reference Manual

Tandy 1000
Technical Reference Manual
8259A/8259A-2/8259A-8
PROGRAMMABLE INTERRUPT CONTROLLER
• iAPX 86, iAPX 88 Compatible
• MCS-80®,
MCS·85
cR
' Compatible
• Eight-Level Priority
Controller
• Expandable to 64 Levels
• Programmable
Interrupt Modes
• Individual Request Mask Capability
• Single
+5V Supply (No Clocks)
• 28·Pin
Dual-In-line Package
• Available in EXPRESS
- Standard Temperature Range
- Extended Temperature Range
The Intel'" 8259A Programmable Interrupt Controller handles up to eight vectored priority Interrupts tor the CPU It is
cascadable tor up to 64 vectored priority interrupts without additional cirCUitry. It is packaged In a 28-pln DIP, uses
NMOS technology and requITes a single + 5V supply. Circuitry is static, requITing no clock input
The 8259A IS designed to minimize the software and real time overhead in handling multi-level Wlorlty interrupts It has
several modes, permitting optimization tor a variety of system requirements
The 8259A IS tully upward compaltble with the Intel' 8259 Software Originally written for the 8259 will operate the
8259A In all 8259 equivalent modes (MCS-80/85, Non-Buffered. Edqe Trlqqered)
OATA
BUS
8ufflA
RiJ0
WA .. - RtAO
~RlfE
lOl,l(
'" .
cs---
CASCA.DE
BUFftR
CO""PA,RATGR
, J IJl,iqAAIJPT MAS.,;, REG
<>1'----_
Figure 1. Block Diagram
2-120
IR2
IR]
IR'
- IR5
- IR6
Figure 2. Pin Configuration

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