System Support

4.4 Real-Time Clock and Configuration Memory

The Real-time clock (RTC) and configuration memory (also referred to as “CMOS”) functions are provided by the SB700 component and is MC146818-compatible. As shown in the following figure, the SB700 component provides 256 bytes of battery-backed RAM divided into two

128-byte configuration memory areas. The RTC uses the first 14 bytes (00-0Dh) of the standard memory area. All locations of the standard memory area (00-7Fh) can be directly accessed using conventional OUT and IN assembly language instructions through I/O ports 70h/71h, although the suggested method is to use the INT15 AX=E823h BIOS call.

0Dh

Register D

0Ch

Register C

0Bh

Register B

0Ah

Register A

09h

Year

08h

Month

07h

Date of Month

06h

Day of Week

05h

Hours (Alarm)

04h

Hours (Timer)

03h

Minutes (Alarm)

02h

Minutes (Timer)

01h

Seconds (Alarm)

00h

Seconds (Timer)

Extended Config.

Memory Area

(128 bytes)

Standard Config.

Memory Area

(114 bytes)

RTC Area (14 bytes)

FFh

80h

7Fh

0Eh

0Dh

00h

CMOS

Figure 4 4. Configuration Memory Map

A lithium 3-VDC battery is used for maintaining the RTC and configuration memory while the system is powered down. During system operation the RTC and configuration memory to draw power from the power supply. The battery is located in a battery holder on the system board and has a life expectancy of three or more years. When the battery has expired it is replaced with a CR2032 or equivalent 3-VDC lithium battery.

4.4.1 Clearing CMOS

The contents of configuration memory can be cleared by the following procedure:

1.Turn off the unit.

2.Disconnect the AC power cord from the outlet and/or system unit.

3.Remove the chassis hood (cover) and insure that no LEDs on the system board are illuminated.

4.On the system board, slide the CMOS clear button (switch SW1) for at least 5 seconds.

5.Replace the chassis hood (cover).

6.Reconnect the AC power cord to the outlet and/or system unit.

7.Turn the unit on.

✎Clearing the CMOS memory has no effect on the Power-on and Setup passwords. Passwords must be cleard using the password-clear jumper as described in section 4.5.1

 

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HP dc5850 manual Real-Time Clock and Configuration Memory, Clearing Cmos
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dc5850 specifications

The HP dc5850 is a desktop computer that was designed for business environments, offering a blend of performance, reliability, and efficiency. Released during the height of the mid-2000s, this system is powered by AMD processors, particularly the Athlon or Phenom series, which ensures that it can handle various computational tasks with ease.

The dc5850 features a compact chassis that adheres to the Microtower form factor. This design not only saves space but also allows for easier upgrades and maintenance. The unit typically supports a range of RAM configurations, with options for up to 8GB of DDR2 memory. This flexibility enables the user to tailor the system's performance according to their needs, whether for basic office tasks or more demanding applications.

Storage options on the HP dc5850 include a 3.5-inch HDD that can accommodate substantial data, with capacities typically ranging from 160GB to 1TB. The inclusion of a SATA interface ensures fast data transfer rates, which is essential for improving overall system performance. Moreover, the dc5850 boasts multiple USB ports, including USB 2.0 and sometimes even USB 3.0, facilitating easy connectivity with peripherals such as printers, scanners, and external drives.

Graphics capabilities on the dc5850 are generally provided by integrated solutions, although users have the option to add discrete graphics cards for enhanced performance in visual tasks. The system often comes with integrated audio, which supports basic multimedia needs without requiring additional sound cards.

In terms of connectivity, the HP dc5850 features built-in Ethernet for wired networking and may also offer options for Wi-Fi capabilities via PCI expansion slots. This makes it suitable for networked business environments, enabling seamless integration into office infrastructures.

The system is designed with energy efficiency in mind, complying with various environmental standards, thereby reducing its carbon footprint. This aspect may also lead to lower operational costs for businesses focused on sustainability.

Overall, the HP dc5850 stands out as a versatile desktop solution, catering to the essential needs of small to medium-sized businesses. With its combination of performance, expandability, and energy efficiency, it remains a noteworthy choice for users seeking reliable computing power in a compact and manageable form.
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