Tandy 1000 Technical Reference Manual

Tandy 1000
Interrupt Function
Technical Reference Manual
The 8088 supports two types of interrupts: maskable (by the CPU, INT) and
non-maskable (NMI). See Figure
7. The 8259A Interrupt Controller is the source
of the INT for the 8088. The 8259A has eight interrupt inputs controlled through
software commands.
It can mask (disable) and prioritize (arrange priority) to
generate INT. These eight interrupts are:
#0 Timer Channel 0
#1 Keyboard
#2 Hard Disk Controller
#3
Modem
#4 RS-232
#5 Vertical Sync
#6 Disk Controller, Floppy
#7 Printer
Software Timer
Keyboard
Code Received
Optional Function, Interrupt on Bus
Optional Function, Interrupt on Bus
Optional Function, Interrupt on Bus
Software Timer for Video
Ready to Receive/Transmit Data
Data Transmission Complete
The NMI interrupt
is not maskable by the CPU but it can be enabled/disabled
by hardware. The enable
is at Port OOAO Bit 7. The enable is cleared by RESET.
There is no specific function assigned to NMI and it is available on the bus.
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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