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Old 19th Dec 2011, 11:09 pm   #12
Join Date: Jan 2007
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 453
Default Re: IMOGen Test Card & Teletext Generator

Hello Parabola,

Originally Posted by Parabola View Post

I think that Jeffrey was being kind to me here by promoting the fact that, in it's current form, IMOGen can store up to six text pages. This is more than the four that RTR's generator stores at one time. This is related to the available PROM space and the number of complete frames stored.

As far as I know, and I know very little about what was offered with Dave Grant's Dinosaur TCGen, it only produces one page of text which contains some design details and credits about the generator itself. I'd be interested to hear differently because it should certainly be able to do at least four if correctly coded to.
In the version of Dave Grant's TC Generator that I have, images are stored in pairs of EPROMs, one pair can store one colour or four monochrome images, a total of four frames. It is, therefore, possible to have four teletext pages per EPROM pair, which represents four pages for a colour image and one teletext page per monochrome image per EPROM pair.

There was no easy way to produce images for Dave's generator before Richard Russell produced his TC Generator. The programming software it uses can also be used to produce files that can, with some manipulation of the data locations, be programmed into a pair of EPROMs that will work in Dave's generator!

As for the reconstruction filter, I was told (I forget by whom) that the one in Richard's generator is better than the one in Dave's generator!


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