Adventure 'A' - Planet Of Death

[stefano]

This is all I could get for the expanded ZX81.
I got it by hand-driving the compiler build process and editing the intermediate assembly source to extract most of the program data and split the program in a first loader which pushes the data block on top of memory and the program core.
To try it you need a zx81 with 32K and the WRX mod. Load and run the first block, then load and run the second block.
Sorry I couldn't make it work perfectly and I'm not sure I'm able to fix it, but I thought that the ZX81 deserved the graphics version of this program after so long time !
I borowed the pictures from OpenClipArt.org (author is "nicubunu"); they were in SVG format and I converted and compacted them with the tool I wrote for z88dk. Not all the pictures are shown correctly but it is fun in any case.

* EDIT * The attachment is actually for a 48K expansion (see the following posts),

[sirmorris]

Where's my time machine?? I need more time!!!

[siggi]

Hi Stefano
I played a little bit and the graphics look nice
Why do call the program "unstable"? It worked perfectly till now ...
Is there something I could test (you asked for help in the beginning of this thread)?

Siggi

[stefano]

Well, on EightyOne some graphics just faded away.. the first picture should have some tree here and there.
The labyrinth shows a strange vertical line and is not fully drawn and so on..
If you see the first picture correctly (a moutains with few trees, then probably it is working correctly.

[siggi]

Hi Stefano
I found some of the problems also on my real ZX81: the first screen seems to be OK, but some screens don't have a picture at all. The maze picture is distorted.

Siggi

initial screen

P1070146_1024x768.JPG (165.74 KiB) Viewed 5468 times

Forest

P1070147_1024x768.JPG (190.33 KiB) Viewed 5468 times

Maze

P1070148_1024x768.JPG (163.09 KiB) Viewed 5468 times

[stefano]

Very odd, I tried it on the emulator and I got totally different "distorsions".
I thought the problem was the data area being modified by some unexpected effect on the high RAM pages.
Now I suspect the problem is different, probably I left too little space for the stack or for some heap area :/

[RWAP]

That would fit in with my findings - the graphics don't seem to be corrupted if I use EightyOne with 48K RAM and WRX Graphics, but do if I use 32K RAM (crashes on 16K RAM)

[stefano]

Ok, I was wrong telling the program was for the 32K expansion.. it's for the 48K indeed !
I forgot that a ZX81 has just.. no base memory. what we need is 16K for program, stack and spare stuff (such as the default D-file), 15K for data and.. 6K for the graphics display file !
So we're closer to 40K.. are the 32K expansions more frequent than the 48K ?
There's still the possibility that the lower 16K area is still too full. If so I could try to rebuild the Whole thing moving also the font.
Another possibility is to try to reduce the graphics data by simplfying the pictures a bit, use the ROM font and to remove the 'save' option.

Siggi ?

[RWAP]

Yes, I would guess the 32K expansions are more common than 48K ones - the ZXpand only has 32K for starters!

[1024MAK]

The very common RAM extensions are the Sinclair, Memotech and various other makes of 16k RAM.
There are also various DIY internal 16k upgrades.
Most software back in the ZX81 heyday was 16k.

Now due to the success of ZXpand, 32k is becoming more common. Memotech also produced 32k RAM expansions, but these are not common. There are also various DIY internal 32k upgrades, but there is more than one than one way to map the RAM. Some have RAM starting at 0x2000 while some start at 0x4000.

Memotech also produced 64k RAM extensions (I have one). These are rare.
There are some DIY RAM extensions that provide 48k or more RAM, but not many people have done this AFAIK.

Mark