AOPEN P5TCAQ User Manual

Appendix A

BIOS revision

AP5T revision 3.4

Rev 3.4

Frequently Asked Question

Note: FAQ may be updated without notice. If
you cannot find the information that you need in
this appendix, visit our WWW home page,
(address: http://www.aopen.com.tw) and check
the FAQ area and other new information.

Q: How can I identify the mainboard BIOS version?

A: The AOpen mainboard BIOS version appears on the upper-left corner of

the POST (Power-On Self Test) screen. Normally, it starts with R and is
found in between the model name and the date. For example:

AP53/AX53 R3.80 Oct.22.1996

Q: How can I identify version of the mainboard?

A: The AOpen mainboard revision appears as Rev x.x on the PCB, near the

PCI slot. For example, for AP5T revision 3.4, the revision number appears
on the PCB as follows:

AP5T MB

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Frequently Asked Questions

Q: Why the AOpen mainboards (MB) do not have cache module

expansion slot?

A: Faster CPU speed requires more difficult and complex MB timing design.

Every trace and components delay must be taken into consideration. The
expansion cache slot design will cause 2 or 3ns delay in PBSRAM timing,
and the extended trace length to the cache module through the golden
finger will further delay the timing by 1 or 2ns. This may result in unreliable
system once the cache module and slot becomes worn. All AOpen MBs
support 512KB PBSRAM onboard. For better performance (around 3%
higher than 256KB), we strongly recommend you to use 512KB onboard.
Otherwise, reliable 256KB is better than unreliable 512KB with cache
module. AOpen is the first company to promote this concept since the
fourth quarter of 1995.

Q: What is FCC DoC (Declaration of Conformity)?

A: The DoC is new certification standard of FCC regulations. This new

standard allows DIY component (such as mainboard) to apply DoC label
separately without a shielding of housing. The rule to test mainboard for
DoC is to remove housing and test it with regulation 47 CFR 15.31. The
DoC test of mainboard is more difficult than traditional FCC test. If the
mainboard passes DoC test, that means it has very low EMI radiation and
you can use any kind of housing (even paper housing). Following is an
example of DoC label.

AP5T

Test To Comply
With FCC Standards

FOR HOME OR OFFICE USE

Q: Can SDRAM DIMM work together with FPM/EDO SIMM?

A: The FPM/EDO operate at 5V while SDRAM operates at 3.3V. The current

MB design provides different power to DIMM and SIMM but connects the
data bus together. If you combine SIMM and DIMM, the system will still
work fine; however, only temporarily. After a few months, the SDRAM 3.3V
data input will be damaged by 5V FPM/EDO data output line. Therefore,
we strongly NOT recommend DIMM and SIMM combined together. There
is one exception, if your SDRAM supports 5V tolerance (such as TI or
Samsung), which accepts 5V signal at 3.3V operating power, you can
combine them.

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Frequently Asked Question

Manufacturer Model Suggested CAS

Latency Time

Samsung KM416511220AT-

G12
NEC D4S16162G5-A12-7JF 2 No
Hitachi HM5216805TT10 2 No
Fujitsu 81117822A-100FN 2 No
TI TMX626812DGE-12 2 Yes
TI TMS626812DGE-15 3 Yes
TI TMS626162DGE-15 3 Yes
TI TMS626162DGE-M67 3 Yes

Q: What is Bus Master IDE (DMA mode)?

A: The traditional PIO (Programmable I/O) IDE requires the CPU to involve in

all the activities of the IDE access including waiting for the mechanical
events. To reduce the workload of the CPU, the bus master IDE device
transfers data from/to memory without interrupting CPU, and releases CPU
to operate concurrently while data is transferring between memory and IDE
device. You need the bus master IDE driver and the bus master IDE HDD
to support bus master IDE mode. Note that it is different with master/slave
mode of the IDE device connection. For more details, refer to section 2.3
"Connectors".

2 Yes

5V Tolerance

Q: What is 3.3V Over-current Protection?

A: The Over-current Protection was very popular implemented on the Baby AT

or ATX +5V/+12V switching power supply. It is very useful to prevent
accident short circuit when you install the mainboard, HDD, add-on cards
into housing. But unfortunately, the new generation CPU and chipset use

3.3V or 2.8V voltage which has regulator to transfer 5V to 3.3V/2.8V, and
makes 5V over-current protection useless. AOpen TX mainboard
AP5T/AX5T with switching regulator onboard support 3.3V (Vcpuio,
chipset, PBSRAM, SDRAM) and 2.8V (CPU Vcore) over-current protection,
in conjunction with 5V/12V power supply provide the full line over-current
protection.

Q: What is CPU Thermal Protection?

A: The higher speed of CPU , the more heat dissipation need to be taking into

consideration. If user does not use correct fan for the CPU cooling, it is
highly possible the CPU can over heat and causing system unstable.
AOpen AP5T/AX5T/AX6F has special thermal detection circuit under the

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