Some pointers needed on a 11/70

From: <(>
Date: Wed Jan 2 14:08:30 2002

Hello All,

First of all a Happy New Year.

And now, something completely different......

Last Saturday, I finally had a chance to spend some time in reviving my
pdp 11/70 which I accuired last summer. With the help of Henk Gooien, we
spend nearly a whole day in cleaning the machine, the backplane, the power
supply, and then rebuilding it.
Of course, we checked the power supply voltages prior to placing the
boards in the backplane, and all voltages were between 5.05 and 5.15 at
the backlane (measured at the connectors of the BP).
Besides some small mistakes (not all PS modules in place for the CPU, and
not having a powered memory box), we managed to get the machine partly
running, that is, the lights are reacting to the 2 knob settings, and some
data is displayed on the console.

However, when depositing some data at address 1000, nothing happens, and
the parity and/or address error light goes on. Same when trying to see
the contents of any (low) address. So, I have a few questions:

- I have heard about a system address register which sets the size of
  the memory, where is this address located?
- At the back of the memory box, there are somw switches and 4 thumbwheel
  switches. What is their purpose?
- Is the ROM boot address still 177560? or must it be 17777560 on the 11/70?
- If I have to limit the cpu to it's bare size (i.e. no FPU), do I need
  to ad or remove some jumpers (as is needed f.e. on an 11/35)?

On a side note, I have heard of the PEP-70 memory upgrade, what is it
exactly? And what about the QED-70 CPU upgrade (or is it replacement)

BTW, the machine has no Massbus pheripherals, it will only use Unibus
devices. I have the machine currently configured with a full cpu, bus
grantcards in the massbus slots, a DL11 for the console, and wide grand
cards in the remaining 4 Unibus slots. There is a M9302 terminator in
the last slot, and a newer boot card in row 1 slot E/F.
The memory box has 256Kb of memory.


Received on Wed Jan 02 2002 - 14:08:30 GMT

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