Paper tape and 8th bit?

Hi Guys, I'm attempting to recover some software from paper-tape. Never actually had a PT reader in my "altair days", I fooled around with magnetic tape systems (audio and 9-track), and later went to the NorthStar disk system... Did a bit of paper-tape stuff with the university systems, but I don't recall any real details. Anyway - I'm using an OP-80A which is a very simple manual feed reader - you position a light over the unit and pull the tape through wire guides over an optical sensor and it provides parallel data. This all appears to work OK. The tape I've been testing with is a Processor Technology "BASIC VDM DRIVER" - it contains driver software for the PT VDM-1 video board. My question - Does anyone know what they are using the 8th bit for? - I get nicely readable ASCII BASIC source out of it, except that the 8th bit seems to be somewhat randomly set on certain characters. If I strip the 8th bit I get what appears to be legit BASIC code. I thought it might be parity, however this does not appear to be the case - the codes 0A (00001010) and 0D (00001101) both appear with the 8th bit clear - If the 8th bit were parity, one or the other should have it set. Other characters always have it set, for example 'T' (54) seems to always appears as (D4). I checked the tape and it's not a read-error the 9th bit is punched on certain characters.. Anyone shed some light? Dave -- dave06a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.classiccmp.org/dunfield/index.html