Tempest Posted June 20, 2021 Share Posted June 20, 2021 I've been thinking about trying that BIOS hack that allows you to skip the startup screen if you push a button (which is how it should have been from the beginning if you ask me). However I seem to recall some people saying that certain games don't work with it because it's not the 100% original BIOS. Does anyone have a list of games that had issues? Does anyone know if they've been patched? 1 Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted June 20, 2021 Share Posted June 20, 2021 (edited) The game that has issues with the fire skip BIOS is Sewer Sam. ChildOfCv documented what the problem was here and highlighted that the fire skip BIOS may cause issues with other timing-critical games. I remember a few others saying that there was possibly another affected game but I can't recall if that is correct or not. I also summarise the various BIOS alternatives here. Because of this issue I now use, and recommend, a BIOS that simply reduces the startup screen duration (my choice being that of what CBS Electronics chose for PAL systems, i.e. 3.3 seconds instead of the 12.65 second NTSC default). Here's more info about that. Edited June 20, 2021 by Ikrananka 1 Quote Link to comment Share on other sites More sharing options...
Tempest Posted June 20, 2021 Author Share Posted June 20, 2021 So using a BIOS that reduces the time doesn't break games but the skip BIOS does? That's interesting. I'm ok with waiting 3 seconds or so, that's fine. Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted June 20, 2021 Share Posted June 20, 2021 6 minutes ago, Tempest said: So using a BIOS that reduces the time doesn't break games but the skip BIOS does? Yes, that's the case. The BIOS was designed to have a configurable startup duration so it's in effect an original feature of the design. However, the fire skip BIOS is a hack that can have unintended consequences with some games. Here's my 3.3 second delay NTSC BIOS if you need it. ColecoVision BIOS OS7 (2019)(Ikrananka)(NTSC)[3.3s Title Delay].rom.zip 2 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted June 20, 2021 Share Posted June 20, 2021 5 hours ago, Tempest said: So using a BIOS that reduces the time doesn't break games but the skip BIOS does? That's interesting. I'm ok with waiting 3 seconds or so, that's fine. The issue is that Sewer Sam (and possibly other games) call into unofficial parts of the BIOS code. Since they are unofficial and undocumented, the idea is that future BIOS revisions may change them as needed, invalidating any behavior you attempted to use. But SS did it anyway. The fire-skip modification is an unofficial mod to the BIOS, but at least it doesn't affect the documented functions. So only the "bad" games might be affected by it. 2 Quote Link to comment Share on other sites More sharing options...
SiLic0ne t0aD Posted June 20, 2021 Share Posted June 20, 2021 Thanks for refreshing my memory on this subject. Good to know about the fire/skip BIOs and it's minor incompatibilities, which I totally forgot about. That's what I currently have in my main rig, but I'll be changing that out for the 3.3 sec one sometime (Thanks for uploading that BTW!). Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted June 21, 2021 Share Posted June 21, 2021 Also the 3.3 sec delay BIOS is what Console5 is now selling to replace the previous no delay they used to sell. I have one of these newer ones but haven't installed it into my CV yet. One game I had nothing but issues was was the initial release of Risky Rick. The game flat our refused to start up at all with the no delay bios installed. It was the main reason I put the original back into my CV and still use that for the time being. I'm sure it would work better with the shorter 3.3 sec delay version and I have the ROM for the game now as well so it is more of less a null issue for me at this point. 2 Quote Link to comment Share on other sites More sharing options...
Bruce Tomlin Posted July 7, 2021 Share Posted July 7, 2021 (edited) On 6/20/2021 at 2:49 PM, ChildOfCv said: The issue is that Sewer Sam (and possibly other games) call into unofficial parts of the BIOS code. This. A long, long time ago (2005-2007) I tried to see just how much I could optimize out of the ROM, so I checked the disassembly of every game I could find to see what parts of the ROM were called. I made a list of those addresses, and marked those in a certain way in my .asm of the ROM, so that I could see in the symbol table dump if they changed. I actually got over 1K of contiguous free space, you could put a small game in there. I may have even made a version with a controller test built in before I got tired of doing Colecovision stuff. So basically the "skip startup screen BIOS" is just someone's sloppy hack that stepped on the wrong bit of code that broke the even sloppier code in a single released game. Here are the notes I put in the source code for my optimized ROM: ; LOCKED ADDRESSES -- THESE *MUST* BE CORRECT OR SOME CARTRIDGES WILL NOT RUN! ; ; In order to allow easy verification, these addresses have labels ; starting with an 'A' and containing the locked address. ; ; These are the important addresses (like vectors), plus a few used by the ; small-time offenders. ; ; 0000 0066 080B 18A3 ; 0008 0069 08C0 18D4. ; 0010 006A 143B 18F7* ; 0018 006C 144D 1968 ; 0020 01B1* 1463 196B ; 0028 01D5 14B4 1CCA. ; 0030 023B. 14C1 1D43 ; 0038 02EE 14C3 1D47 ; 003B. 07E8* 15A3 1F61 ; 158B* ; ; ...and these are the addresses used by three of the four Interphase ; games, most of which have vectors available. ; ; 0213. 114A*. 1BAA* 1D3E*. ; 025E. 18E9. 1C27. 1D57. ; 027F. 1979*. 1C4F* 1D5A. ; 0300. 1B1D*. 1C82*. 1D60*. ; 1105* 1BA3. 1D01*. 1D66*. ; ; These two were called from Boulder Dash, but the call instructions ; themselves may be unreachable from the rest of the game. ; ; 01C1* 026A* ; ; Any address with a '*' is only referenced by ONE game that I can find. ; Note that Interphase games account for 11 out of 15 of these. Any address ; with a '.' has a vector available. Note also that all but two Interphase- ; only addresses (18 of 20) have vectors! Oh the humanity! ; ; These are in the "OS7SYM" file which was provided to Adam programmers: ; ;FREQ_SWEEP EQU 000FCH ! ;ATN_SWEEP EQU 0012FH ! ;DECLSN EQU 00190H ! ;DECMSN EQU 0019BH ! ;MSNTOLSN EQU 001A6H ! Also, f*** Interphase. coleco29.asm ctltest.asm coleco.h Edited July 7, 2021 by Bruce Tomlin added coleco.h for ctltest.asm 4 Quote Link to comment Share on other sites More sharing options...
Tempest Posted July 8, 2021 Author Share Posted July 8, 2021 The Atari 5200 Ultimate SD cartridge has a similar option where you can skip the splash screen before each game. I found that if this is enabled then Pole Position won't work properly. The car just won't control at all and goes off to the upper left. I wonder how many other 5200 games are broken when skipping the splash screen? Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted July 9, 2021 Share Posted July 9, 2021 On 7/7/2021 at 7:28 PM, Tempest said: The Atari 5200 Ultimate SD cartridge has a similar option where you can skip the splash screen before each game. I found that if this is enabled then Pole Position won't work properly. The car just won't control at all and goes off to the upper left. I wonder how many other 5200 games are broken when skipping the splash screen? See I like those Atari splash screens so I wouldn't disable that myself. Quote Link to comment Share on other sites More sharing options...
Tempest Posted July 9, 2021 Author Share Posted July 9, 2021 36 minutes ago, -^CrossBow^- said: See I like those Atari splash screens so I wouldn't disable that myself. I do too, it was on by default and I didn't notice. Quote Link to comment Share on other sites More sharing options...
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