Re: 6809 in a C64

On 24/05/2018 13:48, Anders Carlsson wrote:
>> Or I might remember things badly, were there even scrolling on 
>> Prestel or did you just have everything in one page? 
>
> I can't tell for sure, but I doubt those pages scroll in either direction.

Prestel didn't scroll, but BTX wasn't exactly Prestel

https://en.wikipedia.org/wiki/CEPT_Recommendation_T/CD_06-01

https://en.wikipedia.org/wiki/Videotex#Standards

Meanwhile, the European nationalPostal Telephone and Telegraph 
<https://en.wikipedia.org/wiki/Postal_Telephone_and_Telegraph>(PTT) 
agencies were also increasingly interested in videotex, and had convened 
discussions inEuropean Conference of Postal and Telecommunications 
Administrations 
<https://en.wikipedia.org/wiki/European_Conference_of_Postal_and_Telecommunications_Administrations>(CEPT) 
to co-ordinate developments, which had been diverging along national 
lines. As well as the British and French standards, the Swedes had 
proposed extending the British Prestel standard with a new set of 
smoother mosaic graphics characters; while the specification for the 
proposed GermanBildschirmtext 
<https://en.wikipedia.org/wiki/Bildschirmtext>(BTX) system, developed 
under contract byIBM <https://en.wikipedia.org/wiki/IBM>Germany 
forDeutsche Bundespost 
<https://en.wikipedia.org/wiki/Deutsche_Bundespost>, was growing 
increasingly baroque. Originally conceived to follow the UK Prestel 
system, it had accreted elements from all the other European standards 
and more. This became the basis for setting out the CEPTrecommendation 
T/CD 06-01 
<https://en.wikipedia.org/wiki/CEPT_Recommendation_T/CD_06-01>,^[5] 
<https://en.wikipedia.org/wiki/Videotex#cite_note-5> ^[6] 
<https://en.wikipedia.org/wiki/Videotex#cite_note-6> also proposed in 
May 1981. However, due to national pressure, CEPT stopped short of 
fixing a single standard, and instead recognised four "profiles": CEPT1, 
corresponding to the German BTX; CEPT 2, the French Minitel; CEPT 3, the 
British Prestel; and CEPT 4, the Swedish Prestel Plus. National videotex 
services were encouraged to follow one of the existing four basic 
profiles; or if they extended them, to do so in ways compatible with a 
"harmonised enhanced" specification. There was talk of upgrading Prestel 
to the full CEPT standard "within a couple of years". But in the event, 
it never happened. The German BTX eventually established CEPT1; the 
French Minitel continued with CEPT2, which was ready to roll out; and 
the British stayed with CEPT3, by now too established to break 
compatibility. The other countries of Europe adopted a patchwork of the 
different profiles.^[7] 
<https://en.wikipedia.org/wiki/Videotex#cite_note-7>