Page 1 of 3
How do i get a movement on screen using the ZX81
Posted: Sun Aug 08, 2021 1:24 am
by Crayon21
so far, all i know is rudimentary basic. However, i want to make more than text adventures. I want to make action games and such but I have no clue how to get the character set to move independent of the screen (Space invaders for example).
This is what i want to achieve:
https://www.youtube.com/watch?v=wjb7aBm ... llordsutch
tips?
typo, meant zx81
Re: How do i get a movement on screen using the ZX80
Posted: Sun Aug 08, 2021 7:32 am
by Paul
First you need to program in Assembler,
Then you have to program a video output routine that matches the screen requirements exactly.
After you managed this you will have a loop that waists a definite number of clock cycles.
Now you can begin programming your game.
Every subroutine of your game needs to use exactly the same (matching) number of clock cycles (in other words they have to be shorter and waist the rest of the clock cycles). If one subroutine gets to long you need to split it into two .
Well they you will be nearly there (this is all only theory)
So knowing this we need to give those programmers extra respect that managed to write flicker free games for the ZX80
Re: How do i get a movement on screen using the ZX80
Posted: Sun Aug 08, 2021 10:18 am
by dr beep
You are referring to a ZX81 game and want the same on a ZX80? In (pseudo)hires?
Too much for a startergame.
Re: How do i get a movement on screen using the ZX80
Posted: Sun Aug 08, 2021 9:54 pm
by mrtinb
It looks like the game in the video is based on the dk’tronics hardware, which uses UDG (user defined graphics chars). So it is still text mode, but the chars are changed. Other hardware than dk’tronics that support this is UDG4ZXpand or Chroma 81.
However with a WRX enabled RAM expansion you can make UDG like software with dr.beep’s USCII
viewtopic.php?f=6&t=3124 .
You can also program WRX or PSG (pseudo graphics with unmodified RAM pack), like mentioned above, but using USCII might be a simpler approach.
Re: How do i get a movement on screen using the ZX80
Posted: Mon Aug 09, 2021 12:25 am
by Crayon21
mrtinb wrote: ↑Sun Aug 08, 2021 9:54 pm
It looks like the game in the video is based on the dk’tronics hardware, which uses UDG (user defined graphics chars). So it is still text mode, but the chars are changed. Other hardware than dk’tronics that support this is UDG4ZXpand or Chroma 81.
However with a WRX enabled RAM expansion you can make UDG like software with dr.beep’s USCII
viewtopic.php?f=6&t=3124 .
You can also program WRX or PSG (pseudo graphics with unmodified RAM pack), like mentioned above, but using USCII might be a simpler approach.
where can i find the manual for dk'tronics?
Re: How do i get a movement on screen using the ZX80
Posted: Mon Aug 09, 2021 3:23 am
by XavSnap
Re: How do i get a movement on screen using the ZX80
Posted: Mon Aug 09, 2021 4:24 am
by Crayon21
Re: How do i get a movement on screen using the ZX80
Posted: Mon Aug 09, 2021 12:09 pm
by BarryN
You can do it in BASIC using text.
Code: Select all
10 FOR Y=1 TO 10
20 FOR X=1 TO 10
20 PRINT AT Y,X;" HELLO "
30 NEXT X
40 FOR X=10 TO 1 STEP -1
50 PRINT AT Y,X;" HELLO "
60 NEXT X
70 PRINT AT Y,1;" "
80 NEXT Y
The word hello will go back and forth and advance down the screen.
Re: How do i get a movement on screen using the ZX80
Posted: Wed Aug 11, 2021 12:11 am
by Crayon21
can it be done with graphics?
Re: How do i get a movement on screen using the ZX80
Posted: Wed Aug 11, 2021 2:03 am
by BarryN
Crayon21 wrote: ↑Wed Aug 11, 2021 12:11 am
can it be done with graphics?
Sure, just print the graphics characters. Don't expect hi-res though from BASIC.
