DIGITAL-LOGIC AG

MSB900/L Detailed Technical Manual V1.0

5.6.Timers and Counters

5.6.1.Programmable Timers

An 8253 compatible timer/counter device is also included in the board's ASIC device. This device is utilized in precisely the same manner as in a standard AT implementation. Each channel of the 8253 is driven by a 1.190 MHz clock, derived from a 14.318 MHz oscillator, which can be internally divided in order to provide a variety of frequencies.

Timer 2 can also be used as a general purpose timer if the speaker function is not required.

Timer Assignment

Timer

Function

0

1

2

ROM-BIOS clock tick (18.2Hz)

DRAM refresh request timing (15 µs)

Speaker tone generation time base

5.6.2.RTC (Real Time Clock)

An AT compatible date/time clock is located within the chipset. The device also contains a CMOS static RAM, compatible with that in standard ATs. System configuration data is normally stored in the clock chip's CMOS RAM in a manner consistent with the convention used in other AT compatible computers. To attach an external battery on a MSB900L board refer to section 2.11.1.

5.6.3.Watchdog

The watchdog timer detects a system crash and performs a hardware reset. After power up, the watchdog is always disabled as the BIOS does not send strobes to the watchdog. In case the user wants to take advan- tage of the watchdog, the application must produce a strobe at least every 800 ms. If no strobe occurs within the 800 ms, the watchdog resets the system.

For more information, please refer to the driver/software/BIOS manual “GEODE_LX800-LX900” on the Prod- uct CD. The watchdog feature is integrated in the INT15 function.

There are some programming examples available:

Product CD-Rom or customer download area: \tools\SM855\int15dl\…

5.6.4.ROM-BIOS Sockets

An EPROM socket with 8bit wide data access normally contains the board’s AT compatible ROM-BIOS. The socket takes a 29F020 EPROM (or equivalent) device. The board's wait-state control logic automatically in- serts four memory wait states in all CPU accesses to this socket. The ROM-BIOS sockets occupy the mem- ory area from C0000H through FFFFFh; however, the board's ASIC logic reserves the entire area from C0000h through FFFFFh for onboard devices, so that this area is already usable for ROM-DOS and BIOS expansion modules. Consult the appropriate address map for the MICROSPACE PC-Product ROM-BIOS sockets.

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Compaq MSB900L user manual Timers and Counters, Programmable Timers, RTC Real Time Clock, Watchdog, ROM-BIOS Sockets
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MSB900, MSB900L specifications

The Compaq MSB900 and MSB900L are noteworthy entries in the realm of personal computing, particularly for their cutting-edge features and innovative technologies that defined their era. Positioned as versatile desktop solutions, both models have garnered attention for their robust performance and user-friendly design.

The Compaq MSB900 is equipped with a powerful processor that enhances multitasking efficiency. Its architecture supports a range of demanding applications, making it suitable for both professional and everyday use. Users can expect a seamless experience whether working on complex spreadsheets or engaging in casual gaming.

In terms of memory, the MSB900 boasts expandable RAM options, allowing users to enhance their system's capabilities as needed. The availability of multiple RAM slots provides flexibility for upgrades, ensuring the system can keep pace with future software requirements. Storage solutions in the MSB900 include high-speed hard drives, which contribute to fast boot times and robust data retrieval.

The MSB900L variant steps up the performance with additional features tailored for power users. It incorporates advanced graphics capabilities, offering superior visual experiences for gaming and multimedia applications. The dedicated graphics card provides a substantial boost in rendering performance, making it a worthy choice for graphic designers and video editors.

One of the standout characteristics of the MSB900 and MSB900L is their commitment to connectivity. Both models come equipped with a wide array of ports, ensuring compatibility with various peripherals. This includes USB ports for modern devices, Ethernet ports for wired networking, and legacy connections for older technology, catering to a diverse user base.

Energy efficiency is another key feature of these models. Designed with power-saving technologies, the Compaq MSB900 and MSB900L aim to reduce energy consumption without compromising performance. This focus not only helps to lower operating costs but also aligns with growing consumer preferences for environmentally conscious products.

In summary, the Compaq MSB900 and MSB900L offer a compelling combination of performance, expandability, and connectivity. Their innovative features and user-friendly design make them suitable for a wide range of users, from casual consumers to professional power users. As a testament to Compaq’s legacy, these models continue to be regarded as reliable choices in the personal computing landscape.
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