Paper tape and 8th bit?

[Allison]

>
>Subject: Re: Paper tape and 8th bit?
>   From: woodelf <bfranchuk at jetnet.ab.ca>
>   Date: Sat, 26 Aug 2006 16:48:38 -0600
>     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Chuck Guzis wrote:
>
>> 
>> If you look at the preceding character, is there any correlation to the 8th
>> bit of the next one?  The 8th bit just might be garbage left over and not
>> masked out.
>
>It could be binary.The driver is loaded in the top of memory, and
>seems to patch over a TTY driver. I don't have manual handy
>but it does have a bootstrap loader @ 80H I think, the first
>256 bytes to load in a hex loader.

PT and many of the 8080 micros didn't use the punch/reader (ASR33 usually)
in the same way as the PDP-8 and onter Minis. So conventions existed but
didn't always get applied the same.

 It's not a bin tape, the manual has the source listing.  Its a program "LIST" 
of a PT 5k basic program that loads a long list of DATA nnn,nnn into memory 
at an address and also pokes the output code of the program to point to VDM1 
or Nominal IO depending of sense switch 8 (IN FF; ANI 80; JZ xxxx). Works on
IMSAI or Altair front pannal systems,useless for NS* (no sense sw at FFh).

I still have and use a VDM-1 in a Netronics Explorer 8085.  I havent used PT 
software since '76ish as I wrote a more compact minimal VT52 screen 
emulation for it.


Allison