moroz1999 wrote: ↑
Sun Jul 26, 2020 11:04 pm
Einar Saukas wrote: ↑
Sat Jul 25, 2020 12:30 am
The ZX81 screen only contains 256x192 pixels without attributes, so nothing can be lost in a conversion to SCR (using black INK/white PAPER). Although it would be even better to store ZX81 screens as a simple sequence of 24x32=768 bytes (one byte for each character on screen). Perhaps we can convince @moroz1999 to support this new format?
No problem! I just need a short description and one sample to test it with.
Each S81 file should have exactly 24 rows x 32 columns = 768 bytes (one byte for each character on screen), stored from left to right, top to bottom. The bit 6 of each byte should always be zero (otherwise the file is considered invalid), therefore valid values for each byte are 0..63 or 128..191. Each byte value corresponds to a character image from the ZX81 charset
. The pixel images for the first 64 characters are stored in the standard ZX81 ROM
starting at address $1E00. The other 64 characters are exactly the same characters, but inverted.
The color is always black INK on white PAPER. The resulting image size should be 256 pixels wide by 192 pixels high, without border.
Here's a sample S81 file
and the corresponding SCR file
. Also I already added a S81 screenshot to this page
so it can be used for testing.