New to me PDP-11/03, have a question

[capnrob97]

Hello, this is my first time dabbling with a 'real' PDP-11, I have the PiDP-11 I have been playing with.

On this PDP-11/03, it has a M7270 processor board, 32K ram board M8044 DB, an M8043 4 port serial card (I have port 3 configured as the serial console), and a M8016 YB clock board.

It also came with a homemade wire wrapped control panel with a switch for DC on/off, Run/Halt, and LTC 0n/off

When I connect to the console port and flip the switch to DC On, I get an address 17300 rapidly scrolling up the left side of the console, it appears to be printing the address, a newline, and the address again, over and over.

Reading through the manual for the CPU board, I saw mention of a jumper for boot up mode, I added the jumper to tell it to boot into ODT mode and tried again.

This time a different address is displayed over and over again, 17000.

Not sure why it isn't going into ODT mode and why the constant writing of an address to the console?

Any pointers would be appreciated.

Thanks!

 

[jmdhuse]

Welcome to the forum - the setup you have is a great pace to start!

Here's what I would try...

Take the real-time clock out of the backplane to (eliminate one variable) and, if it is not already inserted, place a jumper on W3 to disable the EVENT interrupt. For boot-up mode, select ODT by having a jumper on W5 and no jumper on W6. When you see the 173000, it is failing as it tries to execute from a boot ROM, which you don't have in your system at this point. If something was driving the BDCOK Q-bus signal rapidly, that would cause a series of reset cycles, each one causing the 173000 to be sent to the console. If you have access to a scope, look at what is happening on the BDCOK and BPOK signals.

Try this and let us know what happens...

 

[capnrob97]

Yes, thank you for your reply, did get it going by doing a few of the items you mention.

I created a duplicate post in Hardware/Tech Support’ as I thought this one was deleted by the mods earlier when it disappeared for a while, figured I posted in the wrong forum or something. I removed the clock card, that disabled the custom control panel, and it booted into OTD.

Mods, please feel free to delete this thread as it is a dupe to one in Hardware / Tech Support forum.