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Member Since 8 Mar 2013
OFFLINE Last Active Today, 12:42 PM

Topics I've Started

Bouncy's obstacle course

Fri Feb 8, 2019 5:30 PM

Almost everything I have made for the TI-99/4A requires a RAM expansion. It's boring to always do the same, so I wanted to try something else.  :)


Here is a preview of a smooth scrolling game that runs on an unexpanded TI-99/4A from an 8K ROM cartridge - no 32K RAM or disk drive required.



The game is currently 6.2K and has 4 levels of 256x20 characters, 2 of which are shown in the video. The reason that is possible is due to lz4 data compressiom, thanks to Tursi and others. The cool thing is that it's running at 60Hz despite storing the map in VDP RAM, and for now it's actually only using 2/5 of the CPU.


I might decide to add another ROM bank of 8K for the full game, but the essential thing is that this could have been produced and sold in 1982, which is not true for a game like Flying Shark that requires a 512K ROM + 32K RAM. 

** New ** Most wanted game poll

Thu Dec 27, 2018 5:20 PM

I hope this time it works. Please vote again if you already voted.

Most wanted game for the TI-99/4A

Tue Dec 25, 2018 4:17 PM

We've been through this excercise many times before, but this time I would like to get some evidence-based inspiration for my next project.


Round 1: post all titles you would like to see converted to the TI-99/4A.


Round 2: a poll to rank the titles submitted during round 1.


Round 3: development of ?


Disclaimer: blah, blah, blah...  :)


Let round 1 begin.



Fri Nov 30, 2018 12:59 PM

My next game is going to be a port of Pyjamarama from the ZX Spectrum. I'm currently approximately 50% done.


Attached File  pyjamarama.png   7.23KB   10 downloads


The reason I chose this game is that the action-adventure genre seems to be under-represented on the TI. I looked for source code and found this excellent disassembly of the Spectrum version: http://www.luny.co.uk/. Thanks to Luny whoever you are...  :)


The source code itself is excellent for portability because it's much less hard-coded than other things from the period. The data structure for the room graphics can be used directly on the TI, and even the game logic (what you need to do to complete different tasks) is coded into a device independent byte code language that just needs a simple interpreter to be executed.


For the graphics, anything the Spectrum can do can also be shown on the TI. We have 8 bytes of color per character where the Spectrum has only one (a color attribute). Spectrum games often rely on color attributes for collision detection, but managing a virtual copy of the attribute table in CPU RAM is easy enough. All sprites are 16x16 which makes it easy to map them to TI sprites, but there are some places with more that 4 sprites on a row that I need to deal with.


As it looks now I will be done before Christmas, but you never know, of course.


Attached File  screenshot (6).png   6.8KB   6 downloads


The Spectrum has 48K so fitting this into 32K might be a struggle. I think a disk version with Super Cart will be one option. Another will be a cartridge with more graphics and sound.

Pinball games

Thu Aug 23, 2018 12:49 PM

I'm interested in knowing more about how pinball games like Pinball Dreams were done. Especially how the collision detection and physics simulation worked.


I found a little bit of info here:



Looking at the collision map it's not clear to me why the obstacles here take up a lot more space than on the playfield map. Is it perhaps because you only check for collision for one pixel at the center of the ball? If you need to check pixels at the edge of the ball instead, how do you know which pixels to check in order to detect all collisions?


I believe it should certainly be possible to make a fast, smooth scrolling pinball game using the F18A, and also a simplified version for the old VDP, given enough ROM or SAMS space.


This preview of Pinball Dreams for the C64 is already rather old, but it's a nice teaser: