Acrosser AR-B9612 Manuel d'utilisateur télécharger pdf (Page 15)

2-10 AR-B9612 User’s Guide

Address Description

17 Low expansion memory byte

18 High expansion memory byte

19-2D Reserved

2E-2F 2-byte CMOS checksum

30 Low actual expansion memory byte

31 High actual expansion memory byte

32 Date century byte

33 Information flags (set during power on)

34-7F Reserved for system BIOS

Table 2-5 Real-Time Clock & Non-Volatile RAM

2.7 TIMER

The AR-B9612 provides three programmable timers, each with a

timing frequency of 1.19 MHz.

Timer 0

The output of this timer is tied to interrupt request 0.

(IRQ 0)

Timer 1 This timer is used to trigger memory refresh cycles.

Timer 2 This timer provides the speaker tone.

plication programs can load different counts into

this timer to generate various sound frequencies.

1 2 ... 10 11 12 13 14 15 16 17 18 19 20 ... 46 47

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Acrosser AR-B9612 Manuel d'utilisateur Page 15