LOWRES -demo

[Paul]

Wow!

[stevenmcdonald]

Amazing work Dr Beep!

I used your editor and looked at its source!

It blows. my mind that it's highly likely that nobody in the world thought to do this in the 43 years since this computer has been released! That's why it still fascinates me to this day!

I took your idea and just to prove a point, knocked up a small demo using just BASIC. Had I been shown this demo code in BASIC back in 1984/1985, I think I would have called it Voodoo magic and then fainted with disbelief at what I was seeing on my black and white TV screen!

UDGDEMO.P

(1.28 KiB) Downloaded 13 times

[Fruitcake]

It's a very interesting new technique. As an optimisation, you can replace the two instructions LD H,D and LD L,E with single instruction EX DE,HL to achieve the same effect but using 1 less byte per row.

[stevenmcdonald]

Wow Paul that is genius! Saving yet more bytes!! I have updated my BASIC program to verify that it works!

UDGNEW.P

(1.25 KiB) Downloaded 10 times

[dr beep]

It's a very interesting new technique. As an optimisation, you can replace the two instructions LD H,D and LD L,E with single instruction EX DE,HL to achieve the same effect but using 1 less byte per row.

That was my first try too, but now try printing 2 lines of telephone, then you get an errordisplay.

Both HL and DE need to have same value.

[Fruitcake]

You are indeed correct. But if you only wanted to display one row of characters then you'd save a byte at least. Or if you wanted to display multiple rows and your program could tolerate having a non-uniform row length then you could start each row with LD H,D / LD L,E:

Listing.gif (4.12 KiB) Viewed 184 times

Output.gif (1.63 KiB) Viewed 184 times

[Lardo Boffin]

I have just uploaded another video of the demo on a CRT TV. Guess I need better video equipment! Hey ho.

https://youtube.com/shorts/xd79n9p23_E? ... SvrMS31jql

[Fruitcake]

It blows. my mind that it's highly likely that nobody in the world thought to do this in the 43 years since this computer has been released!

And technically this technique would work on the ZX80 also, and so that's 44 years that no one else has thought of this!

[dr beep]

You are indeed correct. But if you only wanted to display one row of characters then you'd save a byte at least. Or if you wanted to display multiple rows and your program could tolerate having a non-uniform row length then you could start each row with
LD H,D / LD L,E:

My next game needs fixed length. So I will use 2 bytes.
On the otherhand.... full screen and it is just 1 byte, byte 33 was HALT and becomes LD H,D then add byte 34 LD L,E which will also cause the intrupt.

[dr beep]

I had an idea how to make it work for all 8 lines.

My first try last week did not work flawlessly but my current approach is working.

This is character 8 with the even lines inverted so you get 4 lines on a character.

I need to write a manual how you can do both methods.