diff --git a/cfg/atari7800.cfg b/cfg/atari7800.cfg
index 562dd3857..4d20ab0d9 100644
--- a/cfg/atari7800.cfg
+++ b/cfg/atari7800.cfg
@@ -10,7 +10,7 @@ SYMBOLS {
     __ENCRYPT_BOTTOM__:   value = $ff7a, type = export;
     __ENCRYPT_SIZE__:     value = $80, type = export;
     __MEMORY_TOP__:       value = __ENCRYPT_BOTTOM__, type = export;
-    __INIT_SIZE__:        value = 69, type = export;
+    __INIT_SIZE__:        value = 121, type = export;
     __MEMORY_INIT__:      value = __MEMORY_TOP__ - __INIT_SIZE__, type = export;
     __MEMORY_BOTTOM__:    value = $10000 - __CARTSIZE__, type = weak;
     __FREE_ROM_SIZE__:    value = __MEMORY_INIT__ - __MEMORY_BOTTOM__, type = export;
diff --git a/libsrc/atari7800/clock.s b/libsrc/atari7800/clock.s
new file mode 100644
index 000000000..3b259cfcf
--- /dev/null
+++ b/libsrc/atari7800/clock.s
@@ -0,0 +1,69 @@
+;
+; 2022-03-15, Karri Kaksonen
+;
+; clock_t clock (void);
+;
+
+        .export         _clock, clock_count
+        .interruptor    update_clock, 2 ; (low priority)
+        .constructor    init_clock
+
+        .import         sreg: zp
+	.import		_zonecounter
+        .include        "atari7800.inc"
+
+        .macpack        generic
+
+	.code
+
+;-----------------------------------------------------------------------------
+; Read the clock counter.
+;
+        .proc   _clock
+
+        lda     #0
+        sta     sreg+1          ; Promote 24 bits up to 32 bits
+        lda     clock_count+2
+        sta     sreg
+        ldx     clock_count+1
+        lda     clock_count
+
+        rts
+        .endproc
+
+;-----------------------------------------------------------------------------
+; This interrupt handler increments a 24-bit counter at every video
+; vertical-blanking time.
+; Update the clock only on interrupt while the drawing on screen is on
+; _zonecounter == 1 (from 1st visible scanline to last visible scanline)
+;
+update_clock:
+	lda	_zonecounter
+	and	#01
+	beq	@L1
+        inc     clock_count
+        bne     @L1
+        inc     clock_count+1
+        bne     @L1
+        inc     clock_count+2
+@L1:    ;clc                    ; General interrupt was not reset
+        rts
+
+;-----------------------------------------------------------------------------
+; Set time to zero at startup
+;
+        .segment        "ONCE"
+init_clock:
+	lda	#0
+	sta	clock_count+2
+	sta	clock_count+1
+	sta	clock_count
+        rts
+
+;-----------------------------------------------------------------------------
+; Store time in 3 bytes
+;
+        .bss
+clock_count:
+        .res    3
+
diff --git a/libsrc/atari7800/clocks_per_sec.s b/libsrc/atari7800/clocks_per_sec.s
new file mode 100644
index 000000000..dc09c4396
--- /dev/null
+++ b/libsrc/atari7800/clocks_per_sec.s
@@ -0,0 +1,34 @@
+;
+; 2022-03-15, Karri Kaksonen
+;
+; clock_t _clocks_per_sec (void);
+;
+
+        .export         __clocks_per_sec
+
+        .import         sreg: zp
+	.import		_paldetected
+        .include        "atari7800.inc"
+
+        .macpack        generic
+
+	.code
+
+;-----------------------------------------------------------------------------
+; Return the number of clock ticks in one second.
+;
+        .proc   __clocks_per_sec
+
+        lda     #0
+	tax
+        sta     sreg            ; return 32 bits
+        sta     sreg+1
+        lda     _paldetected
+	bne	pal
+	lda	#60		; NTSC - 60Hz
+	rts
+pal:
+	lda	#50		; PAL - 50Hz
+        rts
+        .endproc
+
diff --git a/libsrc/atari7800/crt0.s b/libsrc/atari7800/crt0.s
index 3d53abfa8..d7cf307ee 100644
--- a/libsrc/atari7800/crt0.s
+++ b/libsrc/atari7800/crt0.s
@@ -5,12 +5,12 @@
         .import		 __RAM3_START__, __RAM3_SIZE__
         .import		 initlib, donelib
         .import		 zerobss, copydata
+        .import		 IRQStub
         .import		 push0, _main
+        .include        "atari7800.inc"
 	.include	"zeropage.inc"
 
 INPTCTRL        =       $01
-OFFSET          =       $38
-CTRL            =       $3c
 
         .segment "STARTUP"
 start:
@@ -50,7 +50,7 @@ _exit:
 
 NMIHandler:        
         inc     _zonecounter
-        rti
+        jmp	IRQStub
 
 IRQHandler:
         rti
diff --git a/libsrc/atari7800/get_tv.s b/libsrc/atari7800/get_tv.s
new file mode 100644
index 000000000..3eb94d54d
--- /dev/null
+++ b/libsrc/atari7800/get_tv.s
@@ -0,0 +1,65 @@
+;
+; Karri Kaksonen, 2022-03-25
+;
+; unsigned char get_tv (void)
+;
+	.include	"atari7800.inc"
+        .include        "get_tv.inc"
+	.export		_get_tv
+	.export		_paldetected
+
+.segment	"DATA"
+
+_paldetected:
+	.byte	$FF
+
+; ---------------------------------------------------------------
+; unsigned char get_tv (void)
+; ---------------------------------------------------------------
+
+.segment	"CODE"
+
+.proc	_get_tv: near
+
+.segment	"CODE"
+
+	ldx     #$00
+	lda     #$FF
+	cmp     _paldetected
+	bne     L8
+L1:	lda     MSTAT
+	and     #$80
+	bne     L1
+L2:	lda     MSTAT
+	and     #$80
+	beq     L2
+L3:	lda     MSTAT
+	and     #$80
+	bne     L3
+	lda     #$00
+	sta     M0001
+	jmp     L5
+L4:	sta     MWSYNC
+	sta     MWSYNC
+	dec     M0001
+L5:	lda     MSTAT
+	and     #$80
+	beq     L4
+	lda     M0001
+	cmp     #$78
+	bcc     L6
+        lda     #TV::NTSC
+	jmp     L7
+L6:	lda     #TV::PAL
+L7:	sta     _paldetected
+	ldx     #$00
+L8:	lda     _paldetected
+	rts
+
+.segment	"BSS"
+
+M0001:
+	.res	1,$00
+
+.endproc
+
diff --git a/libsrc/atari7800/irq.s b/libsrc/atari7800/irq.s
new file mode 100644
index 000000000..ed315a1b7
--- /dev/null
+++ b/libsrc/atari7800/irq.s
@@ -0,0 +1,36 @@
+;
+; IRQ handling (Atari 7800 version)
+;
+
+        .export         initirq, doneirq, IRQStub
+
+        .import         __INTERRUPTOR_COUNT__, callirq
+
+        .include        "atari7800.inc"
+
+	.code
+; ------------------------------------------------------------------------
+
+initirq:
+doneirq:
+        rts
+
+; ------------------------------------------------------------------------
+
+IRQStub:
+        cld                             ; Just to be sure
+        pha
+        lda     #<(__INTERRUPTOR_COUNT__ * 2)
+        beq     @L1
+        txa
+        pha
+        tya
+        pha
+        jsr     callirq                 ; Call the functions
+	pla
+        tay
+        pla
+        tax
+@L1:	pla
+        rti
+