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What process is the Intel® 82840 Memory Controller Hub (MCH) manufactured on?
The Intel 82840 is manufactured on process 856.5 (0.25m technology).
The Intel 82840 MCH defines space for SMRAM which overlaps the RDRAM space. Does this have to be physically separate memory?
As stated in the Intel® 82840 (MCH) Datasheet, section 4.1.2, the SMRAM Controller uses the physical existing RDRAM memory space. Any RDRAM memory behind the extended SMRAM space addresses is not remapped and thus not accessible.
What is the MCH reporting mechanism for Hublink parity errors?
The MCH parity error reporting mechanism for Hublink A, Device 0 is the PCICMD register (address offset 04-05h bit 6). This will generate a SERR message from the MCH to the ICH over the HUB interface if the PCICMD register bit 8 is also enabled.
Does the Intel 82840 MCH support Intel® Pentium® III processors with 512KB L2 Cache?
No, the AGTL Bus signaling levels between the Intel Pentium III processor with 512KB L2 Cache and the 840 MCH are significantly different that the two cannot operate with each other. Specifically, VTT on the processor is 1.25V while VTT on the 840 MCH is 1.50V.
Can the Intel 840 chipset support an ISA Bus?
The Inte 840 chipset does not have support for a direct ISA bus. However, both a PCI to ISA bridge, or LCP to ISA bridge, can be used to obtain ISA functionality. Intel does not manufacturer either of these devices. We recommend using a third-party vendor to achieve ISA Bus support.
What would cause the ICH RTC to not advance, not work, or lose time?
First, please reference application note AP-728, Intel® ICH Family Real Time Clock (RTC) Accuracy and Considerations under Test Conditions. This document contains a lot of tips and techniques on troubleshooting the ICH RTC.
One of the most important considerations of the ICH is that it is very susceptible to moisture. If the component is exposed to the environment for more than 72 hours before being mounted (soldered) to a board, then enough moisture has been absorbed to potentially cause RTC problems. Any exposure more than one week will definitely cause RTC problems. Even longer exposure, such as one month, will cause the RTC to completely fail. Review your manufacturing process to see if the ICH is being exposed to the environment for any such periods of time. One common method of exposure is opening the sealed bag for initial component inspection and then leaving the components to sit on a shelf for some time.
If moisture is the problem, the resolution is simple. Exposed components will need to be rebaked to evaporate all the moisture collected within. The rebake process is described within chapter 8, section 5.2 of the
Intel Packaging Databook. The ICH has a moisture sensitivity level of 4. Note that once the ICH has been soldered down, there is no method to remove the moisture trapped within. Flowing the solder closes all the holes under the BGA device. At this point, all parts will need to be scrapped.
If moisture is not the problem, and grounding the RTCRST# signal helps bring the system up, then the ICH could be placed in a power-down mode, specifically a power failure mode. When in a power failure mode, if BIOS is programmed appropriately, the system will not power back on until RTCRST# is asserted. Page 5-54 of the
ICH datasheet has additional information on this.
Finally, there is an extremely old legacy behavior that seems to be well known in industry but not well documented with RTC circuits. Try toggling the RTC SET bit within the ICH very early in POST. SET controls if the RTC advances or not and comes up Undefined at power up.
Will the Intel® 82801BA (ICH2) be validated with the Intel® 82840 (MCH)?
Intel does not have any plans to validate this combination nor does it have any plans to step the Intel® 840 MCH to support ICH2. Customers planning to use this combination will need to perform their own validation, and must do so at their own risk. |
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Intel® 840 Chipset