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Hello all, I just posted some Ebay auctions - one for a Jaguar Alien vs. Predator boxed. It comes with everything except the marine overlay. eBay Auction -- Item Number: 120923686145 I also have a couple of nice C64 disk drives for auction. One is a Commodore brand 1541-II, the other is a Blue Chip drive. eBay Auction -- Item Number: 120923929693 eBay Auction -- Item Number: 120923710115 There's no reserve - bidding starts at $0.01. Thanks for looking!
AVP Hacking (some notes I wrote down years ago, think I might share them ...) Using the "official" ROM from 1993. Goal: Find out why Alien mode is deactivated. Activate Alien Mode in Menu. Maybe do a cheat for level select. Help: We know its there because someone (http://zenade.angelfire.com/AVP/lynx/avp.html) found out how to activate it by patching into memory as well as selecting the level nr. But this Cheat is not really telling where and how to patch ... 😞 We further know that it was possible to select the alien in the menu in older ROM versions. (which I do not have available...) Findings: Alien Mode is in and "just" deactivated in the menu. It can be activated and the item picture in the menu is appearing, too. There is some conditional branch before the picture is displayed. But it is not clear yet what is this condition... My guess: COMLYNX Mode! Comlynx? Indeed there is support for Comlynx in AvP! Just connect a second lynx and one player can select marine while the other is predator. But: It does not seem to work. At least not with my two Lynxes. Add: With three Lynxes every player gets adifferent character ... means the Alien pops up in the menu as expected. Investigating: First, extract files from rom. We get something like 200 file entries, but a lot of them are zero entries. File 0 is the title picture (as always). Trivia: It is not a single sprite but four, background, alien, vs, predator are seperate sprites. File 1: main code/basic fuction stays resident. File 2,3,5,7: menu and actual game ... swapped in at the same address as needed. File 2 contains Intro? File 3 contains the selection menu! File 5 is engine. File 7 contains the Game Over screen. Remark: switched pics??? Most of the other files are sprite data, but sometimes with some additional data (table?) in front of it. Lets concentrate on the file 3 and look for the menu selection part. And there it is... LDX $06 LDA #$00 L2E22: ORA $0A,X DEX BPL L2E22 BIT #$03 BNE L2E6B BIT #$10 ; Left/Right BEQ L2E46 LDA L2E7A ; CURRENT SELECTION DEC CPX #$02 ; And this is crazy... because x is always -1 here!! BPL L2E3B ; And this is crazy... if this should be cmp this makes more sence... but limits AND #$01 ; And this is crazy... the value to 0 and 1 for the selected character BRA L2E41 ; And this is crazy... L2E3B: CMP #$00 BPL L2E41 LDA #$02 L2E41: STA L2E7A ; Store selection BRA L2E5F L2E46: BIT #$20 ; Left/Right BEQ L2E5F LDA L2E7A INC CMP #$02 ; And this is crazy, too ... must be CPX as above?? BPL L2E56 ; And this is crazy, too ... doesnt make sence AND #$01 ; And this is crazy, too ... BRA L2E5C ; And this is crazy, too ... L2E56: CMP #$02 BMI L2E5C LDA #$00 L2E5C: STA L2E7A ; Store selection L2E5F: LDA L2E7B ; Animation of Frame or similar? INC AND #$03 STA L2E7B JMP L2DBF ; The following is interesting, too L2E6B: LDX $07 LDA L2E7A STA $10,X STA $AD JSR $058e JMP $1822 ; And if we check a bit of code before, we find the following ; This is run when we first enter the menu... LDX $07 TXA STA $10,X STA L2E7A What do we learn from this? a) there is a bug in the avp code b) selection can be 0,1,2 BUT ther is this CPX on something which limits this to 0 and 1 (alien is 2!) c) on start this value is read from $07 Some very nice piece of code is: LDX L2E7A LDY #$07 LDA L2D88,X STA ($AB),Y LDY #$09 LDA L2D8B,X STA ($AB),Y LDA $AB LDX $AC JSR $056e this code is plotting the selection frame ... based on a three entry look-up table. three characters! We learn: L056E is plotting a sprite! looking where it is used will find an additional piece of code which draws one sprite only under a condition: LDA $06 CMP #$02 BMI L2DE4 LDA #$b0 LDX #$52 JSR $056e L2DE4: What sprite is it? yes, the alien head for the menu. (not shown: right above that was the plotting of marine and predator) What do we learn? Based on the value of $06 the alien head is (not) shown in the menu. The same value is used on some loop above the selection code to OR some values which are tested for left/right. What does this mean, why do we want to make an OR if we have only one Lynx... and why is all this keypad reading and storing (not shown at all) done so terribly complicated... based on some indizes... could it mean...yes indeed!!! Checking the main code result in a lot of SERDAT occurances... means: COMLYNX code!!!! => a short check with two Lynxes, yes we have comlynx support. And the complicated code for selection "just" synchronizes the selection between two(?) Lynxes.
Dear all, Please enjoy my lovely podcast interview with the legendary James "Purple" Hampton - he is probably best known for being the producer of arguably the Jag's best game - Alien Versus Predator: http://www.arcadeattack.co.uk/podcast-march-2-2018/ The interview also includes lovely info and stories on his work at LucasArts, the legendary people he worked with, his views on the Jaguar, a lovely tribute to Lance Lewis and much much more... There is also a streamlined written version of the interview here: http://www.arcadeattack.co.uk/james-hampton/ Audio version can also be found on the following links: https://itunes.apple.com/us/podcast/arcade-attack-podcast/id1174983594 https://www.stitcher.com/podcast/arcade-attack-retro-gaming-podcast http://arcadeattackpodcast.podbean.com/?source=pb https://www.youtube.com/watch?v=kNUtmwXTq_4