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MOS 6522 VIA

TIMER SUBSYSTEM SIMULATOR

MOS TECHNOLOGY 6522 · VERSATILE INTERFACE ADAPTER · REV 2.0

TIMER 1 IDLE

T1 COUNTER 0000 $0000

T1 LATCH FFFF $FFFF

IRQ COUNT 0

PB7 WAVEFORM OUTPUT

0

PB7 = 0 | PB7 OUTPUT: DISABLED

TIMER 1 MODE (ACR BITS 6-7)

LATCH VALUE (T1L-H / T1L-L)

T1L-L (LOW BYTE) $00–$FF

T1L-H (HIGH BYTE) $00–$FF

SIMULATION SPEED (φ2 CLOCK)

SLOW30 kHzFAST

FLAGS / INTERRUPTS

IRQ/T1

RUNNING

PB7

REGISTER MAP (VIA OFFSETS)

ADDR	NAME	VALUE
$04	T1C-L	$FF
$05	T1C-H	$FF
$06	T1L-L	$FF
$07	T1L-H	$FF
$0B	ACR[7:6]	$00
$0D	IFR[6]	$00

EVENT LOG

TIMER 2 IDLE

T2 COUNTER 0000 $0000

T2 LATCH-L 00FF $00FF

IRQ COUNT 0

T2 WAVEFORM (TIMEOUT PULSES)

!

IRQ = 0 | MODE: ONE-SHOT INTERVAL

TIMER 2 MODE (ACR BIT 5)

LATCH VALUE (T2L-H / T2L-L)

T2L-L (LOW BYTE) $00–$FF

T2L-H (HIGH BYTE) $00–$FF

PB6 PULSE INPUT (MODE 1 ONLY)

PB6 PULSES: 0

SIMULATION SPEED (φ2 CLOCK)

SLOW30 kHzFAST

FLAGS / INTERRUPTS

IRQ/T2

RUNNING

REGISTER MAP (VIA OFFSETS)

ADDR	NAME	VALUE
$08	T2C-L	$FF
$09	T2C-H	$00
$0B	ACR[5]	$00
$0D	IFR[5]	$00
—	PB6 CTR	$00

EVENT LOG

φ2 CLOCK: — SIM TICKS: 0 T1 STATE: IDLE T2 STATE: IDLE IRQ LINE: HIGH (inactive)