[TUHS] pdp11/34 can't boot. help us !

asbesto asbesto at freaknet.org
Wed Nov 5 05:41:38 AEST 2003

> No. the "broken" board is the M7891, 128Kx18 bit MOS memory. The
> broken chip is E15, a simple SN74LS175.
> Some images of the work in progress here:
> http://www.freaknet.org/asbesto/pdp11/
> stay tuned! :)


pdp11/34 don't boot :(

same problem. so here i want to describe anything i can. 

CPU boards:

slot	conn	option		module		addr	vect
1	a-f	cpu		m8266		n/a	n/a
2	a-f	cpu		m8265		n/a	n/a
3	c-f	ky11-lb		m7859		n/a	n/a
4	a-b	boot		m9312
4	c-f	dl11-w		m7856		177560	60
5	a-f	ms11-ld		m7891
6	a-f	rl11		m7762		174400	160
7	c-f	rx211		m8256		177170	264
8	c-f	dl11-wc		m7856		176500	300
9	a-b	unibus		m9202
9	c-f	u/q bim?(*)	m8217
10	a-b	unibus		m9202
10	c-f	convert.	m7066
11	a-f	generat.	m7067
12	a-f	bitmap		m7068
13	a-f	  =               =
14	a-f	  =               =
15	a-f	  =		  =
18	a-b	uni/term	m9302
18	c-d	video		a011
19	a-b-f	reg.kw11	m7952 (this is written)
(19     a-b	???		m9403
        c-f	reg.kw11	m7952  this is what i see in CPU)
20	a-b	qbus/ter	m9400
20	c-f	dma cont	m8026
21	c-f	q-bus cont	m8036
22	c-f	a/d mur		a017

(*) unreadable

well, this is the list as is taped on the CPU cover, compiled by hand.
i have verified, and all boards are in the place described here, 
except (1)

So, let's try to boot:

1) turning on the chassis 

2) turning on the RX02 floppy module, from rear switch

3) pressing WRITE PROT and turning on the RL02 DISK module, from 
   rear switch

4) turning on the CPU module, from rear switch 

5) checking that disk is UNLOADED (LOAD unpressed).. at this time,
   all 4 RL02 lights are turned ON: LOAD, 0 READY, FAULT and WRITE PROT.

6) turning on main CPU from frontal knob (from DC OFF to DC ON):
   fan & rumors, "DC ON" red led led on. 
   inside the cpu:
   - RED led on M7891 board on 
     (this led, identified as "D3" on my schemes, is described as
     "PAR ERR INDICATOR", connected to pin 6 of E33, a 74S74. 
   - The green led on the board is OFF. looking at the board, i can
     see that is JUMPERED! so, it CAN'T turn on ... someone know why ? 
   - in every restart, the display show a different number (this is
     normal, i think)
   - RL02 Lights status: LOAD is on, 0 READY is off, FAULT is off and 
     WRITE PROT is on.

7) pressing LOAD, the LOAD light turn OFF, the disk will spin up 
   and after about 30 seconds the "0 READY" white light turn on. 

8) pressing "CTRL-BOOT" on the CPU CONSOLE will flash FAULT lights on 
   RL02 just for an istant, and after this nothing happen:
   - RL02 lights status is : LOAD off, READY on, FAULT off, WRITE PROT on.
   - CPU show "165504" and RUN led is off. BUS ERR led is off. MAINT is
     off, the only led on is "DC ON".

9) pressing again CTRL-BOOT obtain the same effect.

during this, nothing happen on serial console.


Booting manually (inserting the octal code to boot from RL02):

this is the boot code, found in "E-10 Loading Software Bootstrap":

location	contents
001000		012701
001002		174400
001004		012761
001006		000013
001010		000004
001012		012711
001014		000004
001016		105711
001020		100376
001022		005061
001024		000002
001026		005061
001030		000004
001032		012761
001034		177400
001036		000006
001040		012711
001042		000014
001044		105711
001046		100376
001050		005007


i wrote stuff in 001000, and i read OTHER THINGS. so i can't
manually boot!!!

writing 111111,222222,333333,444444,555555,666666,777777, i
read    000111,000000,000110,000440,000101,002640,000100

but i read every time different contents :(((

maybe i have to add the bootstrap code in a different location?
maybe the 7891 board is totally broken ???

maybe the problem was the substitution of the SN74LS175N with an
hitachi HD74LS175P ?



Photos of boot sequence, chips, schematics details and something
can be seen on http://www.freaknet.org/asbesto/pdp11. sorry for the 
bad quality but they was taken from a color quickcam.

we are working on a pdp11 section of www.freaknet.org to collect any
useful information.

any help will be appreciated (and ... maybe .. any SPARE PART :)

[asbesto : freaknet medialab : radio#cybernet : GPG key on  keyservers]
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[http://www.freaknet.org/asbesto IW9HGS http://kyuzz.org/radiocybernet]
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