UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Hedghog PSC programmable standards converter

marceljack · 14th May 2021, 8:48 am

The composite output of all home computers was non interlaced in order to avoid a line flicker which would be unaccepatble with a fixed picture displaying text.

The effective scanning was 312 line progressive with 50 Hz frame rate.
The useful line number was 288 but the graphic resolution was generally limited to 640 x 240 or 320 x 240 in order to be able to see the full picture despite the overscan of CRT TVs.

If the standard converter expects only interlaced signals, it will not synchronise properly.
TVs are very tolerant to non standard signals and accept 625i/25 or 312p/50 indifferently.

14th May 2021, 8:48 am	#25
marceljack Pentode Join Date: Apr 2021 Location: Paris, France. Posts: 243	Re: Hedghog PSC programmable standards converter The composite output of all home computers was non interlaced in order to avoid a line flicker which would be unaccepatble with a fixed picture displaying text. The effective scanning was 312 line progressive with 50 Hz frame rate. The useful line number was 288 but the graphic resolution was generally limited to 640 x 240 or 320 x 240 in order to be able to see the full picture despite the overscan of CRT TVs. If the standard converter expects only interlaced signals, it will not synchronise properly. TVs are very tolerant to non standard signals and accept 625i/25 or 312p/50 indifferently.