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Ikrananka

CBS ColecoVision PAL BIOS ROM

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Does anyone have a genuine dump of a CBS ColecoVision PAL BIOS (not the French one)?

 

Every so-called CBS/PAL BIOS ROM I have seen on AtariAge, and online elsewhere, is identical to the North American NTSC BIOS and therefore cannot be the correct dump.

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looks like the French and normal pal bios are identical after checking my dumps

i even dumped my pal again to be sure

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looks like the French and normal pal bios are identical after checking my dumps

i even dumped my pal again to be sure

 

Huge thanks. This makes perfect sense seeing as the both PAL and SECAM have the same number of scan lines (625) and refresh rate (50 Hz) and therefore there is no reason for the CV BIOS to be different. Out of curiosity was the PAL BIOS you've dumped pulled from a UK edition of the ColecoVision or was it from a different PAL territory?

 

Back in 2014, nanochess compared the NTSC and PAL/SECAM BIOS and found the only a few differences between them (which I have embellished below):

  • Some unused space ($FF bytes in NTSC) is filled with trash in the PAL/SECAM BIOS (is this really trash I wonder?).
  • Byte 0x0069 determines the machine type as follows:

    0x3C = NTSC

    0x32 = PAL/SECAM

  • Byte 0x196A determines the length of time the title screen is displayed (I'll be discussing this in another topic I'll be starting shortly).

    0x17 = NTSC (~13 seconds)

    0x06 = PAL/SECAM (~3.5 seconds)

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i think that rom used there was provided by me when i was trying to fix my french machine, i have got that thing working but still have some graphics issues with it which are not related to video ram

it has white vertical ghosting lines visible on screen :/

 

i am not sure if the pal machine is a UK as i was given it, but i would think so because the person who i got it from is also from the UK

 

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This also confirms that all PAL labelled BIOS files posted to AtariAge previously (and online) are in fact mislabelled NTSC BIOS files.

 

In the hope of going someway to correcting this I am attaching both NTSC and PAL/SECAM BIOS files with their naming adjusted to conform to TOSEC requirements. With the CBS ColecoVision not being released until the summer of 1983 I have shown this year in the name of the CBS ColecoVision BIOS file (despite the title screen still showing Coleco and 1982).

 

I'm thinking that these two BIOS files should be added to my game rom dumping project files. I'll get to that update in the near future.

ColecoVision BIOS OS7 (1982)(Coleco)(NTSC).rom

CBS ColecoVision BIOS OS7 (1983)(CBS Electronics)(PAL-SECAM).rom

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Posted (edited)

 

i am not sure if the pal machine is a UK as i was given it, but i would think so because the person who i got it from is also from the UK

 

 

I'm not sure if there is anything externally different amongst different PAL region ColecoVisions to visually differentiate between them. Certainly, the UK and Australian ones look identical as far as I can tell, they have the same RF cable and RF TV connection, and the difference would have been internal in the RF unit design to cater for the different PAL standards the countries employed.

 

Maybe I'll dump the BIOS from my spare UK ColecoVision just to be sure, but I am kind of loathe to start desoldering on a console that hasn't ever been opened.

Edited by Ikrananka

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It makes sense that there wouldn't be a lot of difference in the BIOS at least. The routines contained inside are only for programming the sound, VDC, and input (mostly the VDC). Input and sound are the same, and video has the same programming commands in either region. The VDC uses 256 × 192 pixels no matter the actual vertical resolution of the TV. So the only thing that would have to change is delay values, and the BIOS has only one internal delay, the pause screen.

 

Eventually I'll get my diag shield in a state that I'm happy with, but even as is, it can read the BIOS through the expansion port. It currently just runs it through a CRC algorithm to make sure it checks out, but with a small change it could be made to dump the contents as a hex dump.

 

So are the above posted ROM files the official dumps? If so, I should add the PAL/SECAM one so it can compute the checksum there for comparison. I guess I also ought to at least print out the expected region.

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It makes sense that there wouldn't be a lot of difference in the BIOS at least. The routines contained inside are only for programming the sound, VDC, and input (mostly the VDC). Input and sound are the same, and video has the same programming commands in either region. The VDC uses 256 × 192 pixels no matter the actual vertical resolution of the TV. So the only thing that would have to change is delay values, and the BIOS has only one internal delay, the pause screen.

 

Eventually I'll get my diag shield in a state that I'm happy with, but even as is, it can read the BIOS through the expansion port. It currently just runs it through a CRC algorithm to make sure it checks out, but with a small change it could be made to dump the contents as a hex dump.

 

So are the above posted ROM files the official dumps? If so, I should add the PAL/SECAM one so it can compute the checksum there for comparison. I guess I also ought to at least print out the expected region.

 

Really looking forward to your diag shield - will be very useful.

 

The ROM files are about as official as they can be. The NTSC one has been around for decades and I verified it against a dump I did recently of one of the BIOS chips I pulled from a US console. The PAL-SECAM one was dumped by omf back in 2014 (see link in my post above) and he has verified this against a dump from his PAL console as well. So, yes, I would say that they're good to go.

 

I still might pull the BIOS from one of my PAL consoles to dump - but if you do come up with an expansion port BIOS dumper I'd love to test it.

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as i mentioned my odd video issues previously in this thread on my French machine here are some pictures of what i am getting. if anyone has any insight i would be grateful :)

 

post-18126-0-40470300-1557699229_thumb.jpgpost-18126-0-02896000-1557699218_thumb.jpg

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Well there's your problem - you're trying to play a French game on a French ColecoVision :-D Seriously though, most graphical issues I've heard about/seen are down to power supply or power switch issues. Have you looked into those?

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Is there a special BIOS for Canada or Quebec?

 

I think to remember to have seen a BIOS where text was translated in French . (Mainly , i remember, the text you see when you power on the console without cartridge) . But i don't think it is on version for France.

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I hope you're not talking about the katakana that spells "Risky Rick" :)

 

Do you mean the blue streaks?

yes the blue streaks.

 

Well there's your problem - you're trying to play a French game on a French ColecoVision :-D Seriously though, most graphical issues I've heard about/seen are down to power supply or power switch issues. Have you looked into those?

i am sure i removed / opened / brassowed all contacts / applied dielectric grease / reassembled / resoldered the power switch

 

im pretty sure the power supply is ok as i only have one legit power supply and using it on other machines the video output is fine

saying this i do have anotehr non coleco one (its the replacement one with the din plug on, i could wire that up and check i guess. the components in that thing would be newer so would rule out the PSU, i will investigate this further.

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Okay. Well the image translators work for the construct program. But there’s way too much information to decode the Matrix. You get used to it. I…I don’t even see the code. All I see is blonde, brunette, red-head.

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