A conversion of the Spectrum 16K classic to the Tandy/Dragon.
Back to the old "what if" scenario... If a selection of classic games of the time were also released on the CoCo, would things have been different? Would it even have been technically possible?
Only one way to find out...
When "The Executioner" (Richard Wilson of WinAPE fame) did a bit of reverse engineering on the Spectrum 3D Deathchase, made an Amstrad CPC version and released commented source code, it left an obvious opportunity for people to convert the game to other Z80-based formats. I, naturally, stepped over such a task and jumped straight into the idea of making a 6809 version, not being one to ever make a sensible decision.
The initial target machine is the 16K machine using cassette or disk. Obviously a tighter memory requirement than using a 16K cartridge along with the machine's RAM, but where would I get a cartridge made these days? A very ambitious target would be to make a low-res version that runs off a cartridge and works with the original 4K CoCo, but I will resist that urge for now.
As of yet, I have been unable to get into contact with the original author, Mervyn J. Estcourt, to see how he feels about it. A cassette release would be nice, but this would be very awkward without the permission of Mervyn, he who cannot be found!
3D Deathchase progress.
I've finally got the cartridge! It's a bare board and chip without a case, but it works great on a real CoCo. It might work on a Dragon, but (apart from MESS) I haven't been able to test it.
I'm going to get Roger Taylor of CoCo3.com to make a physical cartridge of Deathchase, so I've made a ROM image and included it in the "Final Version" zip (linked below). If anyone spots any problems with it, let me know. It works under emulators, even in Dragon mode, so I'm hoping that it will work on the real thing!
Do you know Mervyn J. Estcourt? Are you Mervyn J. Estcourt? If so, I'd like to get into contact with him to get permission for a real cassette release through Cronosoft. He's hard to find and a couple of magazines are looking for a little interview too.
Fini! Well, as long as I don't get any bug reports back. Any feedback is appreciated.
This version fits into a 16K CoCo by just 4 bytes! Overall, a tight fit with a few compromises to make it work, but I have finally managed to make a game that will work on a 16K machine without using a cartridge. One piece of proof that a CoCo or Dragon could've competed with the other 8-bits at the time.
3D Deathchase "Final version"
Final version 1.
Final version 2.
Belatedly, I post an update. Energy levels and time available are reduced, so I'm going to keep the sky magenta. The only things left to do are sprite masking and a touching up of your bike graphics. In the meantime, I've used some ANSI art skills! If you squint, it looks like a quite good representation of the original's loading screen.
Getting there, but still a bit awkward. It's 56 bytes within the 16K limit now and has updated graphics (some good, some not so good) but it will need a little bit more added to mask the sprites properly, which is bound to push it back up again. Another problem is that the sky is magenta, instead of cyan, in the "Arctic Patrol" and it would be a vast pain to fix within 16K. Another thing that needs to be fixed is the background colour of text on the panel...
New graphics (ouch).
The menu works, the game loop works, the helicopter and tank are in and quite a few of the sound effects too. I loaded it into my real Tandy for the first time and it was rough, a bit slow but playable. I've added Dragon key support, so it should (hopefully) work there too. This demo should run on any CoCo or Dragon with 32K of RAM.
For CoCo or Dragon, use CLOADM to load the cassette version, then EXEC. Loading time approximately 1 minute and 20 seconds.
Use LOADM"DEATHCHS then EXEC for the CoCo disk version.
Controls: Right joystick or cursor keys and space.
3D Deathchase Rough Demo V0.1.
We have a couple of bikes, some blocky bullets and a kind of status bar. The bullets detect collision with the trees, but no bike effects yet.
Bullets and bikes.
Bullets and bikes (2).
First report... I have been working on this on and off, due to some heavy work commitments. I actually started working on it at weekends a few months ago, but that was purely code conversion with nothing to show for it.
Currently, I can "zoom" through the trees using the cursor keys at the various levels of speed with the ability to move left and right. No collision, sprites, status bar or sky yet. I was thinking of using a bit of artistic licence and making the night-time section a "snowy section" to suit the fixed palette of the Tandy... I will have to remap the colours, somehow. It is a bit slow at the moment, so it will need to be optimised. Most of the "tree" engine is a load of memory copying and I'm using the standard 128x192 resolution mode with 4 colours (6K of data to move around). The graphics are untouched, so these are actually the original 1 bpp graphics running in a 2 bpp mode!
Anyway, I present the first screenshots, even though a video clip would make more sense, but I don't have anything installed that I can use.
(Please remove the CORNEDBEEF to reply).
(C) James McKay, 2010.