I was rather honoured to be asked for an interview about Space Harrier a couple of months ago by Jason Kelk in his capacity as editor of the Homebrew section of Retro Gamer magazine. The interview is in Issue 95 which is out now. Retro Gamer also had a great review of Space Harrier in Issue 94 which I nearly missed, as I don’t always buy every issue.
I just happened to be looking through some of the code the other day and noticed a small performance related bug to do with moving the player missile graphics up and down. It’s a shame I didn’t notice it before really – it’s not like I’ve been poring over the code intently since releasing the game…
Anyway, it’s a tiny performance difference – about 40 machine cycles more than it should be every Vertical Blank, when the man is moving up. (To put it in perspective, there are over 35000 cycles between Vertical Blanks).
The code was clearing more data than it ought, by dropping through to do some unnecessary clearing instead of branching past it. By not having a branch always instruction (no, JMP doesn’t count – it’s a whole 3 bytes and not relocatable!), the 6502 lends itself particularly well to making that kind of mistake – leaving the programmer free to pick the wrong conditional branch after a “then” in ”if…then…else” situations.
Not that you’ll notice any difference, and purely because I was just irritated at finding it, I have put a fixed version in the downloads. I won’t be doing much browsing back through the code again any time soon…
Atari User Magazine kindly asked me to do an interview about Space Harrier, and it’s mentioned in their Blog and out now in Issue 11 They also had a review of Space Harrier in Issue 10
Some of the latest batch of 8Mbit Maxflash Cartridges had a problem with Space Harrier (but not with most other things). Maxflash creator Steve Tucker has created a patch to fix the problem, so that the game works on all cartridges now – thanks Steve! I’ve replaced the downloads with updated ones.
This is the source code and utility tools used to create Atari XL/XE Space Harrier
SH Source.7z (7-Zip File)
Cross-assembler used is ATasm and “sh.asm” is assembled as a raw binary image to produce “sh.bin” (8Mbit Atarimax Maxflash cartridge)
Tools require Microsoft Access and Excel and are mostly specific to Space Harrier
For those who want to play the game on a real Atari XL/XE, but don’t want the hassle of programming the game onto an 8mbit Atarimax Maxflash cartridge themselves, KJMann’s Atari Sales and Service has stepped up to the plate and is offering the game pre-loaded with a nice gloss label, at their Store on page 4 of the Carts Section.
They also have a nice preview video of the final, finished version of the game (rather than work in progress ones I’ve posted previously)
KJMann has been, shall we say, instrumental, in getting the game produced, being none other than Sal Esquivel, who arranged the music for it.
Recent Comments