> On Jun 10, 2017, at 10:35 PM, Paul Koning via cctalk <cctalk@classiccmp.org>
> wrote:
>
>
>> On Jun 10, 2017, at 4:59 PM, Mattis Lind via cctalk <cctalk@classiccmp.org>
>> wrote:
>>
>>> ...
>> BTW. Speaking of dumping. Now that I have a TC11 / TU56 that seems to be
>> working, what is the best way to dump 18 and 12 bit tapes? Is there some
>> PDP-11 OS that can do it or is it assembly programming required? I had
>> hopes that RT11 had such features but it doesn't seem like it could read
>> all 18 bits.
>>
>> Has this already been done? Maybe I can spend time on other things than
>> re-inventing the wheel...
>
> RT-11 FILEX can read TOPS-10 format DECtapes. I don't remember if it does
> PDP-8 DECtapes, that's a bit harder because the block size is different.
>
> If you want a raw block by block dump, I don't know about tools for that,
> though a look at the FILEX source code should give you some ideas. Or the
> tape formatter code, for that matter; the basic idea is to put the RALL
> function to work.
By the way, in RALL mode you're using program I/O to read the 18 bits, so (a)
that pretty much calls for assembly language, and (b) you have to talk directly
to the device and block other interrupts or you'll lose data. FILEX raises IPL
to 6 or 7 to turn off all interrupts including the clock, if I remember
correctly.
paul
