Denial

Hello

Some good news and some bad news. Today I read a post somewhere from someone asking if I'd consider a Vic-20 version of Spyders. This is a game that I wrote a few weeks ago for the PET and C64. I wasn't keen on creating a Vic-20 game because of the 22 character limitation but mainly because I didn't know the registers necessary to port it.

Well... I started out converting it today. It uses ASCII graphics, which I was going to convert into custom graphic eventually.

The bad news, I woke up after a nap to realize that I had inadvertently lost the source code without saving it (it was in a freeze state on CCS64).

So the game is about 90% finished. It's got some bugs... and no, I won't be finishing it. It's too difficult to peck through the code with a ML monitor compared to the ease of editing source code.

So I present to you... the unfinished version of Spyders for Vic-20. Better that you see it, than I delete it (3 hours of work).
It requires memory expansion and to run it is SYS 8192.

Thanks Mr NOP. It was me that asked.

Update

SYS8192 to start. I played on a real VIC20. Keys have to be used as the joystick is not supported.

It is a shame you won't (start again) and bring the game to an end it has real potential. Maybe MisFit or Pixel want to port the C64 or PET version ? You have supplied the code.

Not bad so far!

The source code is available. It's not too hard, most of the registers are the same.

- strip out the C64 color RAM code
- update the keyboard read routine (197)
- add joystick code (which I was going to do had the code not been lost)
- downside the aliens from 32 to... 25?

Basically you'd go in and where there are loops for CPX #32 change most of them to #25 (25 spyders)

Then the low/high byte tables have to be changed where the high bytes are 4 and 5 ($0400 $0500) changed to $10 and $11 for Vic 20 screen ram,

Then the code for checking if the alien fire reaches the bottom of the screen (compares to #$07 for $0700) changed...

Then the math where you see CLC: ADC #40 or SEC: SBC #40 has to be changed to 22 so that fire moves up and down 22 characters not 40.

It can be done, it's just time consuming. It took me about 3 hours and I was so close to finishing.