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Tursi's Blog



Creating an Arcade ColecoVision Clone

Posted by Tursi, 06 August 2015 · 805 views

This is my second time trying to post this.. the first time a browser glitch discarded my post, and I couldn't be bothered to type it up again. But now I feel like it. ;)
 
With Super Space Acer nearing some form of completion after almost 25 years, my thoughts have turned to its final destination, which I'd always hoped was an arcade cabinet. I came...


How to Jump

Posted by Tursi, 05 August 2015 · 517 views

HOW TO JUMP
Ever fired up a platformer, and thought "Damn, this looks great! But why does the player hover when I jump??"
 
It's a very common thing for developers to not really understand how jumping works, and to simply code a fixed speed up for a few frames, then a fixed speed down. The net effect is a very unnatural motion, and if the player is f...


They work! (Added files)

Posted by Tursi, 04 January 2015 · 871 views

So! I built two of the carts today, and they work fine! I'm pretty, to use the UK term, chuffed! (Is that right?)




Just one more layout error noticed - the 74LS00 is too close to the hole, to mount it in a shell I had to trim the post a little bit. (It's a bit snug anyway, but I didn't mind that).

So I have the parts to build 5 of these.. any intere...


Thunder Force Multicart PCBs

Posted by Tursi, 03 January 2015 · 683 views

The PCBs arrived today, a little later than I hoped, but still with time to play with them.

For my first stab at a cartridge PCB, they're not bad. I went with the cheap non-solder-mask, non-silkscreen versions to test.

There were four problems with them.

The first problem was they were slightly too wide, it made for a very tight fit... I trimmed less t...


More TF4 Security - and Patch files

Posted by Tursi, 29 December 2014 · 467 views

I had a playthrough of TF2 and TF3 without incident, but TF4 was still having problems. I found two specific spots that locked up, and was able to save state them to track things down. Eventually, I found a second checksum routine at $781E, which was triggering after the power up animation where you get the enhanced CLAW.

It's pretty much the same as the...


And patching up lives in Lightening Force

Posted by Tursi, 29 December 2014 · 604 views

After doing the extra work to allow single life games in TF2 and TF3, I was a little disappointed that TF4 doesn't allow it - going from 2 stock ships (3 lives) to 0 (99 lives). So, since I'd already found the menu code and it was above the hack-protected (hopefully) area, I wondered about just changing it to work the same as the other two.

When I last l...


Configurable lives in Thunder Force III

Posted by Tursi, 29 December 2014 · 566 views

For kicks, it seemed fair to do the same thing in Thunder Force III.

However, Thunder Force III doesn't /have/ a lives select, only a 'ship speed' and 'game level' option. This makes things a bit harder!

I started by going back to the hacking documentation I linked in an earlier blog, and looking for anything to do with player lives. The function list i...


Extra Lives for Testing Thunder Force 2

Posted by Tursi, 29 December 2014 · 476 views

Thunder Force II - allow lots more lives. TF2 usually allows only 3-5 lives, and it's frankly, overly hard in places. So, for testing, I thought it would be nice to be able to select a lot more lives. (To get into the options menu, hold A while pressing Start on the title page).

Back in Regen, I did a RAM dump at both '5' lives and '3' lives, then loaded...


Ordered PCBs

Posted by Tursi, 27 December 2014 · 413 views

I'm pretty confident now... so I laid out a board (god, it's ugly) and placed an order with ExpressPCB - I should see them next week. If nothing else I can socket one and test more readily, but with a little luck they will now work.

We'll know next week!




Hack Protection in 1992

Posted by Tursi, 26 December 2014 · 525 views

I did some further study on the Thunder Force IV lockup - I found to my pleasant surprise that it reproduced on my hacked version even without the menu. So I was able to dig a bit deeper.

I found that it came down to the branch I had randomly selected on the SEGA screen - the vector table code was okay, but changing those two bytes caused the hang. (Afte...






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