Acrosser AR-B9612 - Manual (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.
Application programs can load different counts into
this timer to generate various sound frequencies.