The start of a new month sees a new C64 game from yours truly… well, “new” in the sense it’s a reworking of something I released last year under the C64CD label. Stercore XD is a horizontally scrolling shoot ’em up and I’m sure my regular fan has just passed out in shock at such an out of character move on my part. Sarcasm aside, I might as well wibble on a bit about technical details since the game isn’t exactly a complex beast with an engaging back story.
The screen scrolls at five pixels a frame – a little slower than the original Stercore on the Spectrum or the direct C64 port which are moving at eight pixels – and uses a wider map which leaves gaps for tidy background colour changes. That map is 2,340 tiles wide, making the background around 240 screens in total and it all barrels past in a little shy of five minutes during play. Since Stercore XD has been squarely aimed at the RGCD competition it needed to run from a 16K cartridge, so the bulk of the game is compressed with Exomizer but the unrolled chunk of background scroll code required to move two and a half times what the Spectrum is dealing with was generated on start up.
Stercore had player and enemy objects passing between two layers and this has been faithfully replicated with hardware sprites in Stercore XD, relying on the hardware sprite priority register and using a similar approach to games like Implosion, Dan Dare or Shadow Skimmer. One background layer is always the background colour the character mulitcolour which that doesn’t get priority over the sprites, the other layer uses the remaining multicolour and character colour, with the latter mostly being used to add dark and light detail. This technique is accurate to half pixels and requires no processor overheads for masking but does require a lot of extra juggling when drawing the graphics.
After that it’s got a slightly extended and tweaked version of the original theme tune which was just an extra half pattern from the original Autotracker-generated tune used to “create” the original Stercore music and, more importantly to the gameplay, there’s a simple attack wave driver which was repurposed from Super Hyperzap. As is usually the case there’s source code – and in this case, work files for those wanting to understand the sprite priority thing – over at GitHub for folks wanting to prod around, although that source isn’t my tidiest piece of work even after it was “sanitised”!
I’m taking a couple of weeks off from the Saturday posts. Specifically, there wasn’t one yesterday because I was prodding around inside my old Dell PowerEdge SC1430 server and trying to get the RAM cooling fan working without any ear-piercing squeals. Dell used a proprietary 5 pin connector on this fan and the cheapest I found online was £25, which feels more than a little excessive and nobody around that price range had it in stock anyway. So I instead took matters into my own hands, which involved removing a wire guard, peeling the sticker off the hub and squirting generous quantities of lithium grease into the little hole. The machine has been running for nearly a day since said bodge was applied and appears happy, so apparently that’s a job well done and the next task is tidying some loose ends and cleaning some crap out of the other fans.
Whilst delving around in one of the local charity shops a few days ago I stumbled across… a boxed, beta release of Windows Vista! The case proclaims it to be part of the Customer Preview Program and it shipped with two DVDs for 32- and 64-bit installs. When booted there’s a watermark on the desktop saying it’s an evaluation copy of Windows Vista Beta 2, gives the build number 5384 and plays Windows XP sounds for events, all of which I know because… well, I installed the 32-bit version on a spare laptop for gits and shiggles.
Unsurprisingly so for something that’s both a beta and Vista it’s very flaky, but some of the problems were fairly extreme for something released to the public; closing the lid suspended the machine which was fair enough but it got stuck making a sound when resuming that only stopped when another played and, after one routine reboot, the login screen completely forgot how to keyboard. I didn’t install any drivers for the wireless network hardware but it couldn’t see the LAN either, so my “plan” to download Chrome and write this post on the Vista install itself fell by the wayside… oh, and it’s a timed beta that I got installed by setting the system clock to late 2006 because the manual said it’d expire at the start of June 2007.
Being curious and resetting the clock back to 2019 whilst writing this post got me a window on boot saying that “your activation period has expired and Windows is no longer working” that didn’t go away when the clock was pushed back again; that’s understandable sure, but it also seems to have completely broken the install since that screen wants to get online to validate any option I select and can’t due to a distinct lack of LAN connection. Instead it just sits there for a few minutes, throws up an “authentication failed” dialog, then rinses and repeats whilst trying to shut down gets it stuck on the “logging off” screen. Oops…
Here’s some more budget-flavoured shooting for this week; I’ve been playing a little Zarkon on the Amstrad CPC. Released in 1987 by Budgie, this is a cheap and cheerful horizontal blaster which employs hardware-based scrolling to give a large, colourful play area. A series of huge dreadnaughts slide past in the background which are defended by ground-and air-based enemies with the only respite being between levels or when things get a little too busy and everything temporarily slows down. Most of the nasties can be blasted, although a few will enthusiastically try to return that favour before they’re destroyed.
Enemy attack waves have been scripted so their patterns can be learnt by the player over time, although the actual position of each airborne nasty is to some degree randomised in order to make things more interesting. Whilst it’s tempting to play for score, getting twonked by an unexpected enemy or bullet sends the player back to the beginning of the level – more frustrating in the latter case since it’s easy to lose track of projectiles moving over the background if not concentrating – so playing it safe and keeping out of harm’s way is probably the wisest approach; learning the enemies’ running order for each stage will help greatly in that respect, as will knowing where the turrets appear and which directions they fire in.
CPC Game Reviews dished out an underwhelming overall score of five and described Zarkon as being “frustratingly difficult” and “cheap-looking”, but I feel that verdict is somewhat harsh; it’s definitely geared towards the challenging end of the scale and there isn’t a lot of variety to the gameplay apart from the occasional new craft on later stages or those aforementioned random enemy placements to mix things up each time, but it’s still reasonably well constructed and, considering the budget price tag, most shoot ’em up fans would’ve got their money’s worth from it back in the day.