Next project: 11/24. Does it need memory?--Progress sorta

Chris Zach cz at
Thu Oct 22 18:51:13 CDT 2020

Hm. Even odder: When I went back to the original CPU board and changed 
the switch settings to that of the working board I got garbage on the 
VT100. Checking with a PC and PUTTY I see it *is* now working but at 
19200 baud even though I have it set to 9600 baud...

Switch packs may be bad among other things. Hm. So the difference was 
switching switch pack 2 (the right one) from
0,0,1,0 0,1,0,0
0,1,0,1 0,1,0,0

E124 (the switch above) is used to set the baud rate for SLU1 to one of 
the two "Baud rates" defined by E135 (the first one, on the left). I'm 
guessing there are two baud rates so you can run async baud speeds if 
you're truly nuts (or are living in 1980 with modems that ran 110 baud 
one way and 1200 baud the other. Kind of like ADSL). Anyway the manual 
says for E124 to set the switches as follows:

Transmit: 	2   1
Receive : 	3   4
Baud rate 1:	ON  OFF
Baud rate 2:	OFF ON

A more confusing truth table cannot be found. Did they misprint this? 
Did engineering just hate the documentation team when they laid out the 
screening for this board? I don't know, but for whatever reason
(switch 1,2) 0,1 Sets transmit to baud rate 1
(switch 3,4) 0,1 Sets receive to baud rate 2

While my board settings were invalid. Ok, kind of makes sense. However 
the fact that I'm running at 19200 means all of E135's switches are 
"off" even though switch 4 and 8 are flipped on. Must be dirty switches, 
time to get the cleaner out....

Anyway, some progress. Now if I jumper the MS11-L for MUD should I put 
it in slot 2 (where the system says "KT24/Mem" but also says it's an EUB 
slot) or slot 7 (the first MUD slot)?

Also I am a bit rusty but I assume "SPC" means small peripheral 
controller WITHOUT DMA and NPR SPC means the slot can support DMA (non 
processor request) or requires a G7270 as opposed to a G727 
knucklebuster to pass the DMA request line?

If so that would mean I would have:
God knows what (G727 or G7270 or nothing?)
MS11-L (first MUD)
RX21 (It's a quad slot SPC with DMA)
930 terminator and G727 (it's the "Unibus" and an SPC without DMA)

What fun!

On 10/22/2020 7:21 PM, Chris Zach via cctalk wrote:
> Interesting. I went up to the attic and opened the Unibus box. I have 3 
> extra 11/24 boards, and I have *NO* idea why. Oi. So anyway I started 
> popping them into the 11/24 chassis to see what happens. Run/halt in 
> halt, looking for anything.
> On the first one (old style) same problem: The CPU board does not talk 
> to the VT52. The second one however brought up ODT with
> 000000
> @
> Progress! I immediately stopped and documented the switch settings:
> Left switch : 0,0,0,1 0,0,0,1
> Right switch: 0,1,0,1 0,1,0,0
> All three lights (clock, 1,2) come on. And I can press enter and get @ 
> so it does listen to the console. However if enter 0/ the CPU locks up 
> and the CPU light goes off. Only way to get back is to power cycle. 
> Likewise starting with the switch in RUN will do this, as will toggling 
> it to BOOT.
> So it's probably unable to access memory. I did try pulling the unibus 
> map, then the memory, then everything but the terminator. Same response. 
> Hm.
> I could try re-jumpering my memory board to appear as MUD memory and try 
> it without the KT24 and see if the problem is there. It's possible. If I 
> did that would I put the memory in slot 2 or leave it in slot 3?
> The other two boards failed the same way as the first. One of the boards 
> is a *new* style one with the ASICs onboard, it has three switch boxes, 
> is there a manual to describe this one?
> I did try to set the switches on the original cpu to match the working 
> one. The original had
> 0,0,0,1 0,0,0,1 (same)       0,0,1,0 0,1,0,0
> Switching thr right switch to 0,1,0,1 does seem to put garbage on the 
> VT52, so something might be happening.
> I also found a M7850 memory board (1mb, for 11/750, 730, and kind of 
> 11/70) which I am guessing won't work in the EUB. Anyone want to swap it 
> for a EUB memory board or a 256K working UNIBUS memory board?
> CZ
> On 10/20/2020 10:02 PM, Jay Jaeger wrote:
>> On 10/18/2020 10:59 PM, Chris Zach via cctalk wrote:
>>> Weird. Set all the switches for the 11/24 CPU and Unibus map, and still
>>> nothing coming out of the serial port. Figured I would document the
>>> settings and see if anyone with an 11/24 can cross-check my settings.
>>> Serial: Because my VT52 has a male RS232 end (factory) and the 11/24 has
>>> a male RS232 end (factory bulkhead) I am using a female-female null
>>> modem cable. This is the same cable I use on the 11/83 CPU and it's
>>> known working (along with the VT52). Is this the right type of cable to
>>> use?
>> Yes, I use a null modem cable plugged into the bulkhead connector as 
>> well.
>>> Switches on the CPU are:
>>> E135: off,off,off,on,off,off,off,on=9600 baud both signal generators.
>> Same here from what is scribbled in my book
>>> E124: off,on,on,off (SLU1 use signal gen 1 for tx and rx)
>> Same Here
>>> E124 5-8: off,on,off,off (no idea what these are)
>> I don't know offhand, either, would have to pull the board to check it.
>>> Slots in use are:
>>> 1--M7133 CPU
>> Same on mine in slot 1, of course
>>> 2--M7134 KT24 Memory map
>> Same as mine on slot 2 as well, of course
>> I have had my system since February, 1988 when a friend and I hauled the
>> 11/24, two RK07's a VT100 and  and TU10 out of U Wisconsin Bascom Hall
>> for about $600.  I have added many things to the system over the year,
>> including a VT11, a DR11C, an Emulex SMD disk controller, etc.
>> It has had one power supply repair (thanks for advice from, I think,
>> Tony Duel about not destroying test equipment while troubleshooting) and
>> early on blown SLU1 dirver/receiver chips which I replaced.
>> After that, I have:
>> M7891 UNIBUS Memory (256K, I think, presumably addressed for 0).
>> G7273 Bus + DMA Grant card
>> M7860 DR11C
>> M7846 RX01
>> M7762 RL11
>> ....
>> and other stuff
>> ....
>> Ending with at VT11 containing an M9302 Boot/terminator
>> SLU1 Interface config,  J3
>> W1 IN (1 stop bit)
>> W5, W7 OUT (disable parity detection)
>> W6, W8 OUT (no parity is generated)
>> E124
>> 1 OFF, 2 ON, 3 ON, 4 OFF
>>     SLU1 and SLU2 both Baud Rate 1
>> E135
>> 9600 Baud (S1, S2, S3 OFF, S4 ON)  (Baud Rate 1)
>> 9600 Baud (S5, S6, S& OFF, S8 ON)  (Baud Rate 2)
>> 1 J2 Pin 13 + 18
>> 2 J2 Pin 11 (EM2)
>> 3 J2 Pin 1 (FM2)
>> 4 N/C
>> 5 N/C
>> 6 N/C
>> 7 J2 Pin 20
>> 8 ----  (I wrote this - probably meant N/C)
>> 9 ----
>> 10 ----
>> 11 J2 Pin 12
>> 12 J2 Pin 6
>> 13 thru 19 ----
>> 20 J2 Pin 16
>> 21 - 24 ----
>> 25 J2 Pin 13 + 18
>> SLU2 Interface config
>> Originally:  Just pin 2 to J2 2+4
>> Baud Rate 2: W9 OUT, W10 IN, W11 OUT, W12 IN, W4 OUT
>> To support a TU-58 on SLU2 I added
>> J4 3-8        J5 2-3
>> J4 4-7        J5 1-7
>> CPU Module Jumpers (I believe, but would have to verify)
>> W2 OUT (power up via location 24, so usually it halts)
>> W3 IN  (allows halt in Kernel mode)
>> W14 IN (Boot address 165000)
>> UNIBUS MAP Jumpers
>> TP11, TP12 presumably OUT(enables diagnostic ROM)
>> W13 presumably IN (enables diagnostic ROM)
>> I can't see Switch E58 without pulling the board to see.  Same, of
>> course, with the jumpers.  I expect they are factory default.
>> NOTE: A a test, I swapped in a CPU 23-001C7AA,
>> Floating Point, 23-002C7AA and Memory Map chip 21-15542-01 from
>> a PDP-11/23, and they naturally worked fine.
>>> 3--M7891 MS11-L memory (configured for extended unibus), green light on,
>>> red light off
>>> 4,5,6--G727
>>> 7-M7982 TS11 tape controller
>>> 8 M8256 RX02 controller
>>> 9 M9302 terminator and G7273 board
>>> When powered on in HALT mode the 11/24 CPU board has the third LED on.
>>> Go to RUN stays on. Go to boot, LED goes off. If the unit is turned on
>>> with the switch in RUN, the light is out.
>>> MS11-L has a green light on at all times. When I forgot the 9302 it had
>>> a red light on as well, but plugging that in and restarting cleared the
>>> red light on the memory.
>> Let me know if you want me to go thru the process of
>> 1) Powering on my system (been just a bit over a year) to do basic checks
>> 2) Pull the boards and document
>> 3) Put them back and do basic checks again.
>> JRJ
>> 2)

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