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

Jay Jaeger cube1 at
Tue Oct 20 21:02:26 CDT 2020

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)


1 OFF, 2 ON, 3 ON, 4 OFF
   SLU1 and SLU2 both Baud Rate 1


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)


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.


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