Epson Apex 386/40 Canadian Product User Manual - Page 105

I/O Port Address 72H, Shadow RAM Control Port

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I/O Port Address 72H 1 Data bit 5 0 Shadow area write protect Shadow area write enable 1 Data bit 6 0 Enable video BIOS shadow Disable video BIOS shadow 1 Data bit 7 0 Enable system BIOS shadow Disable system BIOS shadow Figure 6-10: Shadow RAM Control Port lf you use DTK BIOS, you can enable or disable these two shadow RAM functions through your BIOS setup. Note: 1. If your adapter uses extended memory area as non-cacheable memory in the same way as dual-port memory, you have to configure the non-cacheable memory after the cacheable area is set by means of SW1 --1-3. 2. lf your adapter BIOS is located at 0C8000H-0CFFFFH (within 0C0000H-0CFFFFH) and cannot be cached, you should move the address to a noncacheable area like 0D0000H-0DFFFFH or disable the video shadow function. 3. Cacheable area means physical 32-bit memory installed area and shadow RAM area (0F0000H - 0FFFFFH, 0C0000H - 0CFFFFH) if installed. 12 Chapter 6: Appendix

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I/O Port Address 72H
1
Data bit 5
Shadow area write protect
0
Shadow area write enable
1
Enable video BIOS shadow
Data
bit 6
0
Disable video BIOS shadow
1
Data bit 7
Enable system BIOS shadow
0
Disable system BIOS shadow
Figure 6-10:
Shadow RAM Control Port
lf you use DTK BIOS, you can enable or disable these two shadow
RAM functions through your BIOS setup.
Note:
1. If your adapter uses extended memory area as non-cacheable
memory in the same way as dual-port memory, you have to configure
the non-cacheable memory after the cacheable area is set by means
of SW1 --1-3.
2. lf your adapter BIOS is located at 0C8000H-0CFFFFH (within
0C0000H-0CFFFFH) and cannot be cached, you should move the
address to a noncacheable area like 0D0000H-0DFFFFH or disable
the video shadow function.
3. Cacheable area means physical 32-bit memory installed area and
shadow RAM area (0F0000H — 0FFFFFH, 0C0000H — 0CFFFFH) if
installed.
12
Chapter 6: Appendix