diff --git a/10.01_base/3_test/mulitarb/ma_cons.mac b/10.01_base/3_test/mulitarb/ma_cons.mac
new file mode 100644
index 0000000..93da28f
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_cons.mac
@@ -0,0 +1,104 @@
+
+	.title ma_cons - Serial Console I/O
+corvec= 060		; vector for Receiver
+coxvec= 064		; vector for Xmitter
+
+corbas= 777560		; base addr of Receiver
+coxbas= 777564		; base addr of Xmitter
+
+
+
+	; -- ISRs, increment Interrupt FLags
+
+corifl:	.word	1	; Interrupt flags
+coxifl:	.word	1
+
+corbuf:	.blkw	1  	; data buffer
+coxbuf: .blkw 	1
+
+corisr:
+	mov	@#corbas+2,corbuf	; read char, clear INTR
+	inc	corifl
+	rti
+
+coxisr:
+	inc	coxifl
+	rti
+
+	; -- Initialize device after RESET
+corini:
+	mov	#100,@#corbas	; Bit 6 = Receiver Interrupt Enable
+	clr	corifl
+	return
+coxini:
+	mov	#100,@#coxbas	; Bit 6 = Transmitter Interrupt Enable
+	clr	coxifl
+	return
+
+
+
+	; -------- Console I/O --------
+
+	; puts - print a string
+	; r1 = pointer, r0,r1 changed
+puts:
+	movb	(r1)+,r0	; load xmt char
+	beq	1$		; string ends with 0
+	call	@#putc
+	br	puts		; transmit nxt char of string
+1$:	return
+
+
+	; putnum - print the octal number in r0
+numbf0:  .blkw	 10		 ; space to mount number string
+numbf1	=.
+putnum:
+	mov	r3,-(sp)
+	mov	r0,r2		; r2 = shifter
+	mov	#numbf1,r1	; r1 = buffer pointer, backwards
+	movb	#0,-(r1)	; set terminating 0
+	; repeat 6 times
+	mov	#6,r3
+1$:
+	mov	r2,r0
+	; extract lower 3 bits = octal digit
+	bic	#177770,r0 ; r0 &= 0x07
+	add	#60,r0	; r0 += '0'
+	movb	r0,-(r1) ; write in buffer
+	clc
+	asr	r2	; shift to next digit
+	asr	r2
+	asr	r2
+	sob	r3,1$	; loop for all 6 digits
+
+	call	@#puts
+	mov	(sp)+,r3
+	return
+
+
+	; putc - output a single char
+	; r0 = char
+putc:
+	clr	coxifl		; reset interrupt flag
+	mov	r0,@#coxbas+2	; char into transmit buffer
+1$:	tst	coxifl		; XMT RDY?
+	beq	1$		; no, loop
+	; UART is buffering: char only started to sent now
+	; interrupt active until next putc
+	return
+
+	; getc - poll and input a single char
+	; result in r0
+	; carry clear : nothing received
+	; carry set: char received
+getc:
+	clr	r0
+	tst	corifl
+	bne	1$
+	clc			; Carry clear, no Interrupt, nothing received
+	return
+1$:
+	mov	corbuf,r0 	; Interrupt, return char
+	clr	corifl		; reset interrupt flag
+	sec			; Carry Set
+	return
diff --git a/10.01_base/3_test/mulitarb/ma_kw.mac b/10.01_base/3_test/mulitarb/ma_kw.mac
new file mode 100644
index 0000000..ecf4759
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_kw.mac
@@ -0,0 +1,29 @@
+	.title ma_kw - KW11 test driver
+
+	; KW11 raises INTR at 50 Hz
+
+kwvect = 100		; vector of KW11 line clock
+kwbase = 777546		; base addr of KW11 register
+kwlabl = 'W		; label char
+
+
+	; --- ISRs, increment Interrupt FLags
+kwiflg:	.word	1	; Interrupt flags
+
+kwecnt:	.word	1	; event counter
+
+kwisr:
+	inc	kwecnt			; register as event
+	inc	kwiflg	; set ISR flag
+	rti
+
+	; --- Initialize device after RESET
+kwinit:
+	mov	#100,@#kwbase		; set  interrupt enable
+	clr	kwecnt
+	return
+
+	; --- Restart new INTR
+kwgo:
+	return
+
diff --git a/10.01_base/3_test/mulitarb/ma_rk.mac b/10.01_base/3_test/mulitarb/ma_rk.mac
new file mode 100644
index 0000000..c614d22
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_rk.mac
@@ -0,0 +1,34 @@
+
+	.title ma_rk - RK11/RK05 test driver
+	; RK11 DMA is generated by reading cylinder 0, head 0, sector 0
+
+rkvect = 220		; vector of RK11 controller
+rkbase = 777400		; base addr of RK11 controller
+rklabl = 'K		; label char
+
+	; --- ISRs, increment Interrupt FLags
+rkiflg:	.word	1	; Interrupt flags
+
+rkbuff:	.blkw	400+1	; data buffer: 1 sector = 256 words
+
+rkecnt:	.word	1	; event counter
+
+rkisr:
+	inc	rkiflg	; set ISR flag
+	rti
+
+	; --- Initialize device after RESET
+rkinit:
+	clr	rkecnt
+	return
+
+	; --- Restart new DMA transmission
+rkgo:
+	; read first sector into rkbuff
+	clr	@#rkbase+12		; DA disk address = 0: unit 0, cyl/hd/sec=0
+	mov	#rkbuff,@#rkbase+10 	; BA bus address of DMA
+	mov	#-400,@#rkbase+6 	; WC word count = 256 words
+	mov	#100+4+1,@#rkbase+4	; Command INT ENABLE + "READ" + GO
+	inc	rkecnt 			; register as event
+	return
+
diff --git a/10.01_base/3_test/mulitarb/ma_rl.mac b/10.01_base/3_test/mulitarb/ma_rl.mac
new file mode 100644
index 0000000..c726c3a
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_rl.mac
@@ -0,0 +1,56 @@
+	.title ma_rl - RL11/RL01/2 test driver
+
+	; RL11 DMA is generated by reading cylinder 0, head0, sector 0
+
+rlvect = 160		; vector of RL11 controller
+rlbase = 774400		; base addr of RL11 controller
+rllabl = 'L		; label char
+
+
+	; --- ISRs, increment Interrupt FLags
+rliflg:	.word	1	; Interrupt flags
+
+rlbuff:	.blkw	2*400+1	; data buffer: 2 sector = 256 words
+
+rlecnt:	.word	1	; event counter
+
+rlisr:
+	inc	rliflg	; set ISR flag
+	rti
+
+	; --- Initialize device after RESET
+rlinit:
+	clr	rlecnt
+	return
+
+	; --- Restart new DMA transmission
+rlgo:
+	mov	#rlbase,r1		; r1 = controller base address
+
+	; sequence from boot loader 23-751A9, lot of testing
+	; 1. get status
+	mov	#013,4(r1)		; DA subcmd reset+getstatus
+	mov	#4,(r1)			; CSR do "GET STATUS"
+1$:	tstb	(r1)			; test for ready
+	bpl	1$			; wait
+	; 2. read current track
+	mov	#10,(r1)		; CSR read header cmd
+2$:	tstb	(r1)			; test for ready
+	bpl	2$			; wait
+	; 3. seek
+	mov	6(r1),r2		; MP retrieve cyl/head/sector
+	bic	#77,r2			; set sector to zero
+	inc	r2			; set seek flag, head 0, seek to cyl 0
+	mov	r2,4(r1)		; DA for seek
+	mov	#6,(r1)			; CSR seek cmd
+3$:	tstb	(r1)			; test for ready
+	bpl	3$			; wait
+	; 4. read sector 0+1 and interrupt
+	mov	#rlbuff,2(r1)		; BA bus address of DMA
+	clr	4(r1)			; DA select cyl0/head0/sector0
+	mov	#-512.,6(r1)		; MP set word count
+	mov	#100+14,(r1)		; CSR read data cmd with Interrupt Enable
+
+	inc	rlecnt			; register as event
+	return
+
diff --git a/10.01_base/3_test/mulitarb/ma_ry.mac b/10.01_base/3_test/mulitarb/ma_ry.mac
new file mode 100644
index 0000000..1992d01
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_ry.mac
@@ -0,0 +1,88 @@
+
+	.title ma_ry - RX211/RX02 test driver
+	; RX11 DMA is generated by reading cylinder 0, head 0, sector 0
+
+ryvect = 264		; vector of RX211 controller
+rybase = 777170		; base addr of RX211 controller
+rylabl = 'Y		; label char
+
+rydens = 400		; bit 8 in CSR determines density. 400 or 0
+
+	; --- ISRs, increment Interrupt FLags
+ryiflg:	.word	1	; Interrupt flags
+
+rybuff:	.blkw	200+1	; data buffer: 1 sector = 256 bytes = 128 words for double dens
+
+ryecnt:	.word	1	; event counter
+
+ryphas:	.word	1	; 0 = ISR after "Read sector", 1 = ISR after DMA
+
+
+ryisr:
+	tst	ryphas
+	bne	ryisr1
+	; Phase = 0
+	; RX211 ISR triggered when data in controller buffer
+	; initiate command to DMA data into buffer, then INTR again
+	mov	r1,-(sp)	; push
+	mov	#rybase,r1		; r1 = controller base address
+	; 1. Command "Empty buffer"
+	mov	#rydens+100+2+1,(r1)	; Density, Intr enable + Empty Buffer + GO
+1$:	tstb	(r1)			; wait for TR
+	bpl	1$
+	; 2. Word Count
+.if ne	rydens
+	mov	#200,2(r1)	; double density: 128 words
+.endc
+.if eq	rydens
+	mov	#100,2(r1)	; single density: 64 words
+.endc
+2$:	tstb	(r1)			; wait for TR
+	bpl	2$
+	; 3. Bus Address
+	mov	#rybuff,2(r1)
+	; now starting
+
+	mov	(sp)+,r1	; pop
+	inc	ryphas
+	rti
+ryisr1:
+	; Phase = 1
+	; RX211 ISR triggered on "DMA ready"
+	inc	ryiflg	; set ISR flag after DMA
+	rti
+
+	; --- Initialize device after RESET
+ryinit:
+	mov	#rybase,r1		; r1 = controller base address
+	mov	#rydens+40000,(r1)	; init
+1$:
+	bit	#40,@#rybase
+	beq	1$			; wait for "done"
+
+	clr	ryecnt
+	return
+
+	; --- Restart new DMA transmission
+rygo:
+	clr	ryphas			; Start with ISR Phase = 0
+	mov	#rybase,r1		; r1 = controller base address
+	; sequence from RX02 Floppy Disk System User's Guide (July 1978, EK-RX02-UG-001)
+
+	; 1. command "read sector"
+	mov	#rydens+100+6+1,(r1)	; Density, Intr enable + Read Sector + GO
+1$:	tstb	(r1)			; wait for TR
+	bpl	1$
+
+	; 2. sector address into RX2DB
+	mov	#1,2(r1)		; read sector 1
+2$:	tstb	(r1)			; wait for TR
+	bpl	2$
+
+	; 3. track address into RX2DB
+	mov	#0,2(r1)
+	; now starting
+
+	inc	ryecnt 	; register as event
+	return
+
diff --git a/10.01_base/3_test/mulitarb/ma_strings.mac b/10.01_base/3_test/mulitarb/ma_strings.mac
new file mode 100644
index 0000000..d2d87c7
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/ma_strings.mac
@@ -0,0 +1,17 @@
+
+	.title ma_strings - String constants
+shello:
+	.byte	15,12		; space, CR, LF,
+	.ascii	/*** Multi Device Interrupt&DMA test ***/
+	.byte	15,12		; CR, LF
+	.ascii	/^C to stop./
+	.byte	15,12		; CR, LF
+	.byte	0
+
+
+sbye:
+	.byte	15,12
+	.ascii	/Good Bye!/
+	.byte	15,12 	; CR, LF
+	.byte	0
+
diff --git a/10.01_base/3_test/mulitarb/multiarb.mac b/10.01_base/3_test/mulitarb/multiarb.mac
new file mode 100644
index 0000000..4ca25a5
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/multiarb.mac
@@ -0,0 +1,200 @@
+	.title Multi Arbitration DMA/INTR test
+
+	; *************************************************
+	; Exercises several devices in parallel,
+	; each with INTR and DMA
+	; For a device XX we have
+	; XXENAB - flag to enable devcie
+	; XXBASE - base address of devcie
+	; XXVEC - the INTR vector
+	; XXISR - Interrupt Service
+	; XXIFLG - flag which is incremented in ISR
+	; XXBUF - data buffer for DMA transfer
+	; XXINIT - Initialize device after RESET
+	; XXGO - subroutine to initiate DMA and INTR
+	; XXECNT - event counter, indicates activity
+	; XXLABL - single char label to print activity
+	;
+	; Devices are
+	; CO - serial console
+	; RK - RK11/RK05 disk
+	; RL - RL11/RL02 disk
+	; RY - Serial RX211 Floppy,
+
+	; enable tests
+kwenab	=	1
+rkenab	=	0
+rlenab	=	0
+ryenab	=	0
+
+	.enable AMA
+	.asect
+
+	; *************************************************
+	; Vectors
+
+	. = corvec
+	.word	corisr		; RCV interrupt
+	.word	340
+	. = coxvec
+	.word	coxisr		; XMT interrupt
+	.word	340
+
+.if ne kwenab
+	. = kwvect
+	.word	kwisr		; periodic interrupt
+	.word	340
+.endc
+
+.if ne rlenab
+	. = rlvect		; RL11
+	.word	rlisr
+	.word	340
+.endc
+
+.if ne rkenab
+	. = rkvect		; RK11
+	.word	rkisr
+	.word	340
+.endc
+
+.if ne ryenab
+	. = ryvect		; RX211
+	.word	ryisr
+	.word	340
+.endc
+
+psw	= 177776
+monitr	= 165020		; Monitor addr for back jump
+
+	; *************************************************
+	; Main
+	. = 1000
+stack	= .-2
+start:
+	mov	#stack,sp
+	clr	@#psw		; priorty level 0, allow INTR
+	; Initialize devices
+	reset
+	call	corini
+	call	coxini
+.if ne kwenab
+	call	kwinit
+.endc
+.if ne rkenab
+	call	rkinit
+.endc
+.if ne rlenab
+	call	rlinit
+.endc
+.if ne ryenab
+	call	ryinit
+.endc
+
+	mov	#shello,r1	; Print "Hello" message
+	call	puts
+
+	; main loop: check interrupt flags, restart DMA
+	; process serial input
+loop:
+	call	dokbd		; check keyboard input
+	call	dodev		; check device activities
+	br	loop
+
+
+
+	; --- check keyboard input
+dokbd:
+	call	getc
+	bcc	9$		; nothing received
+	; process char in r0
+	cmpb	r0,#3
+	bne	1$
+	mov	#sbye,r1 	; ^C: print "Bye", back to monitor
+	call	puts
+	jmp	monitr
+1$:
+	; echo chars without special meaning
+	call	putc
+9$:
+	return
+
+	; -- check device activities
+dodev:
+	; For all devices: restart device DMA if Interrupt received
+.if ne kwenab
+	tst	kwiflg
+	beq	1$
+	clr	kwiflg
+	call	kwgo
+	mov	#kwlabl,r0	; progress printout
+	mov	#kwecnt,r1
+	call	progrs
+1$:
+.endc
+
+.if ne rkenab
+	tst	rkiflg
+	beq	2$
+	clr	rkiflg
+	call	rkgo
+	mov	#rklabl,r0	; progress printout
+	mov	#rkecnt,r1
+	call	progrs
+2$:
+.endc
+.if ne rlenab
+	tst	rliflg
+	beq	3$
+	clr	rliflg
+	call	rlgo
+	mov	#rllabl,r0	; progress printout
+	mov	#rlecnt,r1
+	call	progrs
+3$:
+.endc
+.if ne ryenab
+	tst	ryiflg
+	beq	4$
+	clr	ryiflg
+	call	rygo
+	mov	#rylabl,r0	; progress printout
+	mov	#ryecnt,r1
+	call	progrs
+4$:
+.endc
+
+	return
+
+
+	; progress
+	; check if the counter with address in r1 is at
+	; 1024. if yes, print the char in r0
+progrs:
+	bic	#776000,(r1)	; mask counter to 0..1023
+	bne	9$
+	call	putc		; is at 0: print label character
+9$:
+	return
+
+
+
+	.include ma_cons.mac
+.if ne kwenab
+	.include ma_kw.mac
+.endc
+.if ne rkenab
+	.include ma_rk.mac
+.endc
+.if ne rlenab
+	.include ma_rl.mac
+.endc
+.if ne ryenab
+	.include ma_ry.mac
+.endc
+	.include ma_strings.mac
+
+	.end
+
+
+
diff --git a/10.01_base/3_test/mulitarb/test.simh_pdp11 b/10.01_base/3_test/mulitarb/test.simh_pdp11
new file mode 100644
index 0000000..c962960
--- /dev/null
+++ b/10.01_base/3_test/mulitarb/test.simh_pdp11
@@ -0,0 +1,25 @@
+; UNIBUS machine to verify "multi arbitration" test program
+; To run under PDP11GUI
+
+; for all devices:
+;	unit 0 is attached to an empty scratch disk
+
+set cpu 11/34
+set cpu hist=100
+set throttle 2m
+set clk 50hz
+
+set rl enabled
+set rl0 rl02
+attach rl0 scratch.rl02
+
+set rk enabled
+attach rk0 scratch.rk05
+
+set rx disabled
+set ry  enabled
+set ry0 double
+attach ry0 scratch.rx02_dd
+
+# PDP11GUI
+set stdio telnet=23