AR-B1474 User¡¦s Guide

If you want to generate IRQ15 signal to warn your program when watchdog times out, the following table listed the relation of timer factors between time-out period.

Time Factor

Time-Out Period (Seconds)

0C0H

3

0C1H

6

0C2H

12

0C3H

18

0C4H

24

0C5H

30

0C6H

36

0C7H

42

Table 4-2 Time-Out Setting

NOTE: 1. If you program the watchdog to generate IRQ15 signal when it times out, you should initial IRQ15 interrupt vector and enable the second interrupt controller (8259 PIC) in order to enable CPU to process this interrupt. An interrupt service routine is required too.

2.Before you initial the interrupt vector of IRQ15 and enable the PIC, please enable the watchdog timer previously, otherwise the watchdog timer will generate an interrupt at the time watchdog timer is enabled.

4.4.2Watchdog Timer Enabled

To enable the watchdog timer, you have to output a byte of timer factor to the watchdog register whose address is Base Port+4. The following is a BASICA program which demonstrates how to enable the watchdog timer and set the time-out period at 24 seconds.

1000

REM Points to command register

1010

WD_REG% = BASE_PORT% + 4

1020

REM Timer factor = 84H (or 0C4H)

1030

TIMER_FACTOR% = %H84

1040

REM Output factor to watchdog register

1050

OUT WD_REG%, TIMER_FACTOR%

 

.,etc.

4.4.3 Watchdog Timer Trigger

After you enable the watchdog timer, your program must write the same factor as enabling to the watchdog register at least once every time-out period to its previous setting. You can change the time-out period by writing another timer factor to the watchdog register at any time, and you must trigger the watchdog before the new time-out period in next trigger. Below is a BASICA program which demonstrates how to trigger the watchdog timer:

2000

REM Points to command register

2010

WD_REG% = BASE_PORT% + 4

2020

REM Timer factor = 84H (or 0C4H)

2030

TIMER_FACTOR% = &H84

2040

REM Output factor to watchdog register

2050

OUT WD_REG%, TIMER_FACTOR%

 

.,etc.

4.4.4 Watchdog Timer Disabled

To disable the watchdog timer, simply write a 00H to the watchdog register.

3000

REM Points to command register

3010

WD_REG% = BASE_PORT% + 4

3020

REM Timer factor = 0

3030

TIMER_FACTOR% = 0

3040

REM Output factor to watchdog register

3050

OUT WD_REG%, TIMER_FACTOR%

 

., etc.

4-7

Page 36 Page 38
Page 37
Image 37
Sony 486DX, DX4, AR-B1474 manual Watchdog Timer Enabled, Watchdog Timer Trigger, Watchdog Timer Disabled
Page 36 Page 38

DX4, AR-B1474, 486DX specifications

The Sony 486DX, AR-B1474, and DX4 are notable examples of advanced computing technologies from the early to mid-1990s, a time when personal computers were rapidly evolving to meet increasing user demands. These systems played a pivotal role in shaping the landscape of modern computing.

The Sony 486DX is built around the popular Intel 80486 microprocessor, which was a significant step up from its predecessor, the 386. The 486DX featured a 32-bit architecture and introduced integrated cache memory, which greatly enhanced data processing speeds and overall system performance. Operating at clock speeds typically ranging from 25 to 100 MHz, the 486DX models provided a solid foundation for running more sophisticated software applications and advanced games of the era.

Accompanying the 486DX was the AR-B1474 motherboard, designed to maximize the potential of the 486 architecture. This motherboard featured support for up to 512 KB of level 2 cache memory, further boosting performance for data-heavy tasks. The AR-B1474 also included extensive connectivity options, with ISA slots for legacy devices, as well as support for EISA, making it compatible with a wide range of hardware peripherals. This versatility made the AR-B1474 a popular choice among builders of custom desktop PCs during its time.

The DX4, another significant milestone, built upon the 486 architecture by introducing a clock-doubling technique. By effectively allowing the processor to perform operations at up to three times its base clock speed (typically 75 or 100 MHz), the DX4 could handle even more demanding applications, thereby providing users with significant performance improvements without requiring a complete overhaul of their systems.

Both the 486DX and DX4 processors facilitated advancements in multimedia capabilities, with improved graphics rendering and audio performance that supported CD-ROMs and early gaming technologies. This made them particularly appealing to consumers looking for a versatile machine for both work and entertainment.

Overall, the combination of the Sony 486DX, AR-B1474 motherboard, and DX4 processor exemplifies a significant chapter in computing history, showcasing how hardware advancements seamlessly integrated with user needs for performance and flexibility. As these technologies laid the groundwork for future innovations, they remain noteworthy for their contributions to the evolution of personal computing.
Top Page Image Contents