Z80 Computer - Part 18 VGA Horizontal Characters

This time I finally manage to get some pixel data on the screen and display some characters from a font set. I explain the different parts of the circuit and how it works.
We take a look at the characters being displayed horizontally in a row on the screen. Right now each row just gets repeated, so the next step would be to add a vertical character counter.
Font taken from: www.jimblimey....

[@jesusmolo]

Thank you very much for giving us your knowledge. This is magic in my eyes.

[@phils_arcade]

Really enjoy what you are doing. Keep up the great work.

[@tiborbogi7457]

Another successful step in your project. Continue what you doing, don't change anything. 😀

[@alexfooify]

Liked before I even saw the video because I'm hyped to see this!

[@colonelbarker]

Ditto!

[@SteveRaynerMakes]

I'm sorry if it disappoints, I talk way too much. I promise to talk less in the next one. There is a problem, I don't seem to be able to write to the EPROM chip any more, so I can't change the contents. I'll need to order a replacement. I'm thinking it should not be too much more work to display the next row of characters as we move down the screen.

[@colonelbarker]

@@SteveRaynerMakes No, it's all good. Nice and clear explanations of what you're upto. On my similar circut I ended up putting 161 counters for the current H character and V character that would reset on character 32 horizontally and 24 vertically, and they would increment when you sent it a new ascii character. Then used the "load". On the 161s to reset the counts to outside the blanking area.

[@byteforever7829]

I liked at start great video and project as a whole

[@kensmith5694]

I assume that the EPROM will be replaced with a RAM so you can do pixel graphics. There are a few somewhat useful things I can suggest: If you focus on doing one of the 3 colors to make a full screen, as you go you can imagine adding the extra RAM etc for the other 2 colors. You are reading bytes from the RAM/EPROM at about 1MHz. With a bit of cleverness, you can arrange the Z80's timing so that the Z80 can slip its accesses between the reads. The Z80 can have a chunk of memory space and an I/O register for its addressing of the RAM space. The Wait/ pin, I think can do that for you. Each time the Z80 read or writes the memory space for the VGA memory, the wait causes it to go a bit slow if needed. On the write, the Z80 will hold its bus steady for you so your mux to switch onto the pins of the RAM will be simple. On read you may need an HC374 to hold the bits as the VGA goes on with its life.

[@SteveRaynerMakes]

It will be interesting to see what you think of the next video, which somewhat goes into these topics. Unfortunately the EEPROM no long seems to accept new data, so for now I'm stuck with what's in it. It's annoying because the first 8 bytes contain zeros, so we are not really seeing what is going on right now. RAM is on order, so I'm hoping a can move forward soon. I am finding this part of the project trickier than expected.

[@kensmith5694]

@@SteveRaynerMakesI sometimes think all problems are trickier than they seem. I have been designing stuff for a while