Sprites scratchpad

[hendrikbez]

I am using 4.7 and are reading the doc that has come with it, I am reading now in Sprite Images that you can use scratchpad to grab a image, but I do
not understand it, I did try to lad a tap file, but it is not working.

Can anyone please explain it to me, what sort if file must the screen$ file be and what is a screen$ file.

[alessandro]

Hi, first of all, if you do not know what a SCREEN$ file is, maybe you don't have (without offense ) much experience with a Spectrum.

A SCREEN$ file is a file containing a screen image. It is normally loaded at the address of the Spectrum RAM dedicated to the display, i.e. from 16384 to 22527 it contains the high resolution data (pixels) and from 22528 to 23296 the low-resolution attribute (INK, PAPER, BRIGHT, FLASH) data. Therefore it is always 6912 bytes long.

In order to save the screen image in a file you must enter SAVE "picture" 16384,6912; to load it back, LOAD "picture" 16384,6912. "16384,6912" can be also abbreviated to SCREEN$. Consult Chapter 20 of the Spectrum BASIC programming manual to know more.

That said, the scratchpad is used to avoid you the effort of drawing sprite images pixel by pixel. You can draw your sprite images by using an external software like ZX-Paintbrush and exporting the screen file as .TAP or .TZX. Then, as soon as you enter the sprite editor in AGD, press L and then Y to load the screen file into your emulator (or real Spectrum). Move the flashing cursor over the sprite image you want to copy by pressing the arrow keys, then press 0 to copy the sprite image and K to paste it into the sprite editor. Press G to recall the scratchpad screen when you are in the sprite editor screen.

Be ware though; albeit extremely useful, the scratchpad is known to be somewhat buggy and erratically prone to cause memory corruption. There are a couple of threads in this forum about that issue.