TD Systems TDL-11 QBUS (SCSI?) card

Jon Elson elson at
Mon May 4 20:41:22 CDT 2015

On 05/04/2015 12:54 PM, Noel Chiappa wrote:
>      > From: Seth Morabito
>      > Well now I have egg on my face...
> Don't worry, you're not the only one... :-)
>      > No, actually it DOES work.
> Wow. Live and learn.
> Or maybe actually DMA indeed _doesn't_ work with the CPU stopped
Yes, some models of the PDP-11 do not handle DMA requests 
when halted.  I'm pretty sure the 11/45 does.
And, I'm pretty sure the 11/05 does NOT, as I recall not 
being able to perform disk requests directly from the console,
but had to write a short program that went into an infinite 
loop after commanding the controller card to perform a transfer.


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