prime.mix

* Example program - table of primes
* (Knuth, vol 1, p 144)

L	equ	500		# of primes to find
printer	equ	18		Unit # of printer
prime	equ	-1		Memory area for table of primes
buf0	equ	2000		Memory area for BUFFER[0]
buf1	equ	buf0+25		Memory area for BUFFER[1]

	orig	3000
start	ioc	0(printer)	Skip to new page
	ld1	=1-L=		P1. Start table.  J <- 1.
	ld2	=3=		    N <- 3.
2H	inc1	1		P2. N is prime.  J <- J + 1.
	st2	prime+L,1	    PRIME[J] <- N.
	j1z	2F		P3. 500 found?
4H	inc2	2		P4. Advance N.
	ent3	2		P5. K <- 2.
6H	enta	0		P6. Does PRIME[K] divide N?
	entx	0,2
	div	prime,3
	jxz	4B		    R = 0?
	cmpa	prime,3		P7. PRIME[K] large?
	inc3	1		P8. Advance K.
	jg	6B		    Jump if Q > PRIME[K].
	jmp	2B		    Otherwise N is prime.

2H	out	title(printer)	P9. Print title.
	ent4	buf1+10		    B <- 1.
	ent5	-50		    M <- 0.

2H	inc5	L+1		Advance M.
4H	lda	prime,5		P10. Set up line. (Right to left)
	char
	stx	0,4(1:4)
	dec4	1
	dec5	50		(rI5 goes down by 50 until nonpositive)
	j5p	4B
	out	0,4(printer)	P11. Print line.
	ld4	24,4		    Switch buffers.
	j5n	2B		    If rI5 = 0, we're done.
	hlt

* Initial contents of tables and buffers:

	orig	prime+1
	con	2		First prime is 2.
	
	orig	buf0-5
title	con	"first"
	con	" five"
	con	" hund"
	con	"red p"
	con	"rimes"
	
	orig	buf0+24
	con	buf1+10		Each buffer points to the other.
	orig	buf1+24
	con	buf0+10
	
	end	start

* End of prime.mix