Yes, I've read this too.
There ist also a rebuilt version of that ROM around with printing dropped and read, data, restore reimplemented by backporting these from the Spectrum.
What exactly do Plot and Unplot do?
Re: What exactly do Plot and Unplot do?
In theory, there is no difference between theory and practice. But, in practice, there is.
Re: What exactly do Plot and Unplot do?
The ZX81 ROM was supposed to have...
DATA
DRAW
PRINT TO
READ
RESTORE
UNDRAW
But as mentioned these items were given up for the print routines.
DATA
DRAW
PRINT TO
READ
RESTORE
UNDRAW
But as mentioned these items were given up for the print routines.
Re: What exactly do Plot and Unplot do?
You can find details here.
Re: What exactly do Plot and Unplot do?
when printinting the coordinates increases from top to bottom , left to right. whith plot they increases from the bottom.Freya wrote: ↑Sun Feb 19, 2023 11:36 pmBut how is this different to using Print AT when you have a char based display file?dr beep wrote: ↑Sun Feb 19, 2023 7:44 pm A character can also be 4 pixels. a bit like character 129 to 143 on the ZX Spectrum.
PLOT will set the large pixels in a character on the screen.
Since the screen is character based you can't plot a pixel at the position of a character unless the character is the graphical character 0 to 7 or 128 to 135.
UNPLOT will erase the plotted pixel.
I'm wondering what was the point of the plot keyword at all on the zx81.
Couldn't you do exactly the same thing with Print AT?
Freya
you can use prtint at but for any calculated pixel (if you whant to draw a line or cirrcle) you will need to preserve somehow the other three "pixels" involved in that character...
(edited by moderator 1024MAK)
Last edited by 1024MAK on Mon May 15, 2023 8:43 am, edited 1 time in total.
Reason: Tidy up quote
Reason: Tidy up quote
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
Re: What exactly do Plot and Unplot do?
With PLOT you don't need to calculate the character to be set.bola_dor wrote: ↑Mon May 15, 2023 2:15 am
But how is this different to using Print AT when you have a char based display file?
I'm wondering what was the point of the plot keyword at all on the zx81.
Couldn't you do exactly the same thing with Print AT?
when printinting the coordinates increases from top to bottom , left to right. whith plot they increases from the bottom.
you can use prtint at but for any calculated pixel (if you whant to draw a line or cirrcle) you will need to preserve somehow the other three "pixels" involved in that character...
Is there already a plotted point or not?
Ie
pos1 is set and you add pos2. character adds 2
pos1 is set and you add pos4, character adds 134