83Plus:BCALLs:50B3

Synopsis

Official Name: Chk_Batt_Low

BCALL Address: 50B3,50B6,80F0,80F3

Check the batteries.

Inputs

• None

Outputs

• Z=1: Batteries are low
• Z=0: Batteries are good

Registers Destroyed

• All

Comments

This is not just checking bit 0 of port 2. It puts the calculator into a special mode, creates a delay, polls bit 0 of port 2, and puts the calculator back to normal. BCALLing 50B6 is slightly different from 50B3 because a small delay is done before the routine. BCALLs 80F0 and 80F3 are the boot page versions of these routines.

Example

B_CALL Chk_Batt_Low
ret z
B_CALL ChkFindSym
ret c
ld a,b
or a
ret nz
AppOnErr errHand
B_CALL Arc_Unarc
AppOffErr
errHand:
ret