D C
Figure 6-11: 36-Pin Expansion Bus I/O Channels
Math Coprocessor Control
The math coprocessor functions as an I/O device through I/O port
addresses hex 0F8, 0FA and 0FC. The microprocessor sends OP
codes and operands to I/O ports. The microprocessor also receives
and stores results through the same I/O ports. The “busy” signal sent
by the processor forces the microprocessor to wait until the coproces-
sor is finished executing.
The following describes the math coprocessor controls:
OF0
The latched math coprocessor busy signal can be cleared with an 8-bit
“out” command to port F0. The coprocessor will latch “busy” if it asserts
its error signal. Data output should be zero.
OF1
The math coprocessor will reset if an 8-bit “out” command is sent to
port F1. Again, the data output should be zero.
24
Chapter 6: Appendix
Summary of Contents for Apex 386SX/20
Page 1: ...PEER 2030 2 O M H z 3 8 6 S X S Y S T E M U ser s Manual ...
Page 15: ...Chapter 1 System Overview ...
Page 38: ...Chapter 2 Setting Up Your System ...
Page 43: ...Figure 2 2 The Location of W9 80386SX and 80387SX Chapter 2 Setting Up Your System 5 ...
Page 48: ...Figure 2 6 512KB Total Onboard System Memory 10 Chapter 2 Setting Up Your System ...
Page 49: ...Figure 2 7 640 KB Total Onboard System Memory Chapter 2 Setting Up Your System 11 ...
Page 50: ...Figure 2 8 1 MB Total Onboard System Memory 12 Chapter 2 Setting Up Your System ...
Page 51: ...Figure 2 9 1 5 MB Total Onboard System Memory Chapter 2 Setting Up Your System 13 ...
Page 52: ...Figure 2 11 2MB Total Onboard System Memory B 14 Chapter 2 Setting Up Your System ...
Page 53: ...Figure 2 12 3MB Total Onboard System Memory Chapter 2 Setting Up Your System 15 ...
Page 54: ...Figure 2 13 4MB Total Onboard System Memory 16 Chapter 2 Setting Up Your System ...
Page 55: ...Figure 2 14 5MB Total Onboard System Memory Chapter 2 Setting Up Your System 17 ...
Page 61: ...Chapter 3 Operating Your System ...
Page 80: ...Chapter 4 Keyboard ...
Page 90: ...Chapter 5 Troubleshooting ...
Page 98: ...Appendix ...
Page 123: ...Chapter 7 Glossary ...