Intel 386 User Manual

13-13
SYNCHRONOUS SERIAL I/O UNIT
The SSIO Unit can be operated either by using a polling method or through interrupts.
• Figure 13-12 shows a basic flowchart for using the polling method to receive data through
the SSIO.
• Figure 13-13 shows a basic flowchart for the Interrupt Service Routine necessary when
using interrupts to receive data through the SSIO. If interrupts are used, follow the below
sequence for initialization:
1. Initialize the SSIO.
2. Initialize the interrupts - ICU initialization, Interrupt Service Routine, etc.
3. Unmask the interrupts on the ICU.
Figure 13-12. Receive Data by Polling
A3396-01
ROE=0
?
Yes
Error
Routine
Initialize SSIO
RHBF=1
?
Read Data
(SSIORBUF)
No
No
Yes

Intel 386 Specifications

General

Architecture	x86
Clock Speed	12 MHz to 40 MHz
Transistor Count	275, 000
Data Bus Width	32-bit
Address Bus Width	32-bit
Instruction Set	x86
Introduced	1985
Maximum Memory	4 GB
Operating Modes	Real mode, Protected mode, Virtual 8086 mode
MMU	Yes
Voltage	5V
Model	Intel 386
Package	PGA
Process	1.5 μm to 1 μm