Sunday 4 February 2024

Converting VIC20 Multi-Part Games - Vegas Jackpot

In one of my Patreon update posts, I mentioned that there was a 5th game in this last round of conversions, but I was not going to write it up. Ever since, I have been bombarded by constant demands by literally nobody, so I have finally relented and written it up.

The 5th game to be revisited was Vegas Jackpot, a nice little fruit machine simulator. I had the Atari 800XL version of this and remember playing this quite a lot (or maybe more loading it so my mam could play it).

This one was held back for three reasons.

  1. It was just a little over 4K, which was annoying because it would take up an 8K slot.
  2. It is bit difficult to play without the instructions that are printed int the cassette sleeve.
  3. TFW8b hates it.

Not put off by any of those things, I went ahead and converted it.

It is a fairly simple two part game, part 1 puts up the title and loads part 2, the game itself.

Part 1 is a BASIC program, which is a bit difficult to follow on the VIC screen, and because it starts the code to draw the randomly multicoloured border around the screen.

At the end, it does a simple LOAD command to load part 2, which is a standard machine code program with a 10 SYS xyz line at the start.

For a change, let's look at that in CBM .prg Studio (, the tool I use to write the BASIC programs for this sort of thing.

Line 10 sets the background and border colour black and clears the screen.

Line 20 defines a random colour function

Lines 30-60 draw the four lines of coloured blocks that make up the border.

Line 70 jumps over the oddly placed routine at 80

Line 80 is the draw routine

Lines 90-210 draw the title screen text

Line 220 waits for a keypress

Line 230 loads and runs part 2

Normally with something like this, I would change that last line to something like SYS 41088 so it would just back into the cartridge ROM to load part 2 into RAM and run the game.

Part 2 starts with a "PRESS F7 TO START" screen, a hint that F7 is the key to use to spin the reels, but not really enough information to play the game.

Here I decided to add a page of instructions.

I tried to fit this into the style of the previous title screen, and listed the important control keys.

I moved the border drawing lines to the end, and turned those into a routine that I could GOSUB once at the start, and again before drawing the second page.

The extra instructions took the final size to about 5K, but it was always going to be over 4K anyway.

Time will tell if I managed to sneak this into a future update. This week we have been presented with two nice games to add, one 36K RPG, and one progressing well and looking to be 32K. So there will be a little more trimming to do and I might finally get rid of Q*Bert.......


Penultimate +2 Cartridge

The Penultimate +2 Cartridge is in stock at The Future Was 8 bit, note the new website is

More info in a previous post:


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