Chopper Commando for DOS

Back in my teens I aspired to create my own computer games and actually made some nifty little games, but I didn’t ever distribute them. Today’s game, Chopper Commando was made by Mark Currie when he was 15 and did make it out in 1990. It’s a fairly simple arcade helicopter game in which you’re given a mission to complete.

It was written with Turbo Pascal 5 using the Borland Graphics Interface (or BGI). The game uses CGA 4 colour graphics at 320×200 which are mostly drawn using the basic line and fill functions from the BGI library. So artistically the game has a fairly simple line-drawn style that does the job. Sound is also fairly basic, with a few simple beeps coming from the PC speaker.

Upon starting the game you select your pilot from the roster, the number of bombs you can carry and finally the difficulty of the mission. Each difficulty setting has 5 unique missions which is chosen at random each time you play. There is a bit of variety in the missions, some are strictly destruction, whilst others involve deliveries or retrieval of items.

Controls aren’t as intuitive as I’d like, but once I slowed the game down I managed to progress quite well with the keyboard controls. To move you tap the direction you want to move and you gain speed in that direction, in order to stop you have to tap the reverse direction until you slow down and stop. It’s not the easiest way to handle controls, but I managed to make it work for me. I tried using the mouse, but that just resulted in a crash (the helicopter not the game), this could be because I was using Dosbox to play.

Destroying bad guys isn’t too hard, there are four weapons to use for dispatching your foes. First is a basic gun that fires forward. I found it best for shooting targets in the air but the bullets also slow down and fall to the ground, so you can destroy ground targets with it. There are also basic bombs which basically behave like the gun without the forward movement, these are easier to use on ground targets. You have the option to use missiles, but I found they were more likely to get me killed so I didn’t tend to use them. Finally there is a mega bomb which has a larger explosion radius.

Chopper Commando is a fairly simple game, but it has a lot of little extra details that make it charming and fun. The game uses a different colour palette for day and night missions. You can eject from a damaged helicopter and run around throwing grenades until a spare one arrives, and after missions there is a short piece of text from the office that makes fun of you when you die, or congratulates you upon success.

Obviously it’s not very technically impressive, but it’s quite fun. I looked for the Authors website, but it appears to be down, but you can find this on the Classic Dos Games website with a slightly updated version that fixes some bugs and source code.

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SparcStation Desktop project.

Unfortunately I’ve been neglecting my poor old Sun hardware, mostly because of time and space constraints. I thought I’d try to go some way to correcting this by actually beginning the process of setting up the SparcStation 20 as a vintage desktop work station. I’d been planning on doing this for ages, as long ago as when I built the replacement server machine.

Hardware wise I’ve not acquired anything new, although everything needed a test and some basic cleaning to get it working. I’m still having issues, but I’m unsure if it’s an hardware fault or a problem with the software I’m installing. We’ll get to the software in a moment, first we’ll look at the hardware installed.

At the moment I have 3 CPUs in the machine. They are all V8 Supersparcs with two 50Mhz chips on one module and a 60Mhz one on a module on it’s own. Each module has 1Mb of cache memory which doesn’t sound like much now, but was a large amount when these machines first appeared.

Frame Buffer

I’ve currently got about 304Mb of memory installed, I had more but unfortunately one of the sticks that was in it fails to detect anymore. I’d like to have a VSIMM as that would allow me to use the built in cg14 frame buffer (graphics card) which is probably the best performing one available for machines of it’s type. I managed to purchase a 2Mb TGX+ frame buffer and adapter to connect it to a VGA screen, which is doing an odd resolution of 1152×900 at 8 bits per pixel. It’s obviously not the fastest, but it does the job. I’ve selected an 136Gb 10K RPM SCA drive for the hard disk, certainly a bit of overkill, but it would just be sitting on my shelf otherwise.

The initial issue I had was stack under run errors after the boot screen came up and the machine attempted to boot. My first instinct was of course failed memory, which lead me to find the undetected memory module. But no matter which memory I ran I had the same problem. After some poking into the system environment (kinda like the BIOS settings in the PC but without the nice interface.) I found some items that were not at their defaults and changing them back seems to have fixed the stack under run.

Dual CPU MBUS module

Unfortunately that’s not the end of the issues, as after installing and running NetBSD for a while the machine will hang, reset or have a watchdog timer trigger. This certainly could be faulty RAM, but the power supply is also a potential suspect as is the operating system itself. I need to follow this up with some more testing, unfortunately I don’t have a spare PSU to test with.

Software wise I’m much more prepared and have had much more success. I’ve been using Qemu, which does full-system emulation for a number of old and different platforms, including Sparc systems. Qemu has been useful for building packages and the kernel specifically for my machine. Something I had done ages ago when I first intended to do the install.

At the time I built for NetBSD 6.1.4 which is the OS I’ve installed and tried out on the machine. It’s out of date by quite some margin now, so I’ve set up a new virtual machine to start work on getting 7.1 packages and kernel built. It has a bunch of improved hardware support, particularly in the frame buffer acceleration, so I’m keen to see how it goes. I’m still building packages I want for it, but I’m happy with 7.1 under qemu so far. I’m hoping the improved hardware support helps with the hang/watch dog/reset issues.

When it’s all done, I’ll post about what it’s like to use the machine for specific tasks, like say browsing the web and checking email.