How do i get a movement on screen using the ZX81

Anything Sinclair ZX Basic related; history, development, tips - differences between BASIC on the ZX80 and ZX81
Crayon21
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Re: How do i get a movement on screen using the ZX80

Post by Crayon21 »

bola_dor wrote: Mon Aug 30, 2021 7:30 am Did you realize that OP asked about ZX80?
There is no PRINT AT
And there is not an easy way to animate something in the screen..
Not in BASIC
files from Eighty One are .O
No, this is for the zx81.
In Heck, there are two options for perpetual torment:

Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
:twisted:
bola_dor
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Re: How do i get a movement on screen using the ZX80

Post by bola_dor »

As said before, ZX80 action games is a really difficult task, let alone hig resolution graphics. It's doable but needs a lot of knowledge and to be done in assembler.. with routines as described by Paul.
I don't know your skill levels at programing.. If you are starting with I suggest you to follow Input magazine courses. https://archive.org/details/Input_Vol_1 ... 7/mode/2up mainly based for spectrum although these firsts chapters are easily ported to ZX81.
You can try z88dk which is a C cross compiler with some zx80 libraries.. again most of the work there is on the spectrum side but you can learn a lot there.
If you really want to do it at ZX80 it's BASIC does not have any graphics sentences, you can use the graphics characters but only half of them are directly accessible from the keyboard. You can't read the keyboard from basic.. you can't plot a pixel.. and you can't see the screen while the program is running, while every single issue.may have a workarround is not easy nor fast....
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Moggy
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Re: How do i get a movement on screen using the ZX80

Post by Moggy »

As already mentioned it takes a colossal amount of skill but is achievable.

Have a look at the metropolis demo posted here....

viewtopic.php?f=6&t=2707&hilit=metropolis


Very complex admittedly but should spur you on to do something simpler of your own.
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Paul
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Re: How do i get a movement on screen using the ZX80

Post by Paul »

Easiest way to get a movement on the screen using a ZX80 is to change the vertical hold setting on the TV.
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stefano
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Re: How do i get a movement on screen using the ZX80

Post by stefano »

You might still try to get some weird effect, e.g. using the PAUSE command to keep the display stable for a bit, and keeping a program loop around it forcing the TV to loose sync and recover it in sequence.
Similarly it could be a sequence of short PAUSE commands for a different timing. Sadly the numeric argument to be passed to PAUSE will still steal a lot of time..
Moggy
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Re: How do i get a movement on screen using the ZX80

Post by Moggy »

stefano wrote: Sun Nov 07, 2021 1:59 pm You might still try to get some weird effect, e.g. using the PAUSE command to keep the display stable for a bit, and keeping a program loop around it forcing the TV to loose sync and recover it in sequence.
Similarly it could be a sequence of short PAUSE commands for a different timing. Sadly the numeric argument to be passed to PAUSE will still steal a lot of time..
It should be pointed out that this wont work on any zeddy using the Big Bang ROM as the PAUSE routine has been modified and the "jitter" effect has been removed from it.
Crayon21
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Re: How do i get a movement on screen using the ZX80

Post by Crayon21 »

bola_dor wrote: Tue Aug 31, 2021 7:22 am As said before, ZX80 action games is a really difficult task, let alone hig resolution graphics. It's doable but needs a lot of knowledge and to be done in assembler.. with routines as described by Paul.
I don't know your skill levels at programing.. If you are starting with I suggest you to follow Input magazine courses. https://archive.org/details/Input_Vol_1 ... 7/mode/2up mainly based for spectrum although these firsts chapters are easily ported to ZX81.
You can try z88dk which is a C cross compiler with some zx80 libraries.. again most of the work there is on the spectrum side but you can learn a lot there.
If you really want to do it at ZX80 it's BASIC does not have any graphics sentences, you can use the graphics characters but only half of them are directly accessible from the keyboard. You can't read the keyboard from basic.. you can't plot a pixel.. and you can't see the screen while the program is running, while every single issue.may have a workarround is not easy nor fast....
thank you
In Heck, there are two options for perpetual torment:

Eat the Puckerberry and suffer for eternity:
drink nothing but a cocktail of The Last Dab and Mexican Cake blended and served with
habanero slices
:twisted:
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