v13-v15 problem with iso image larger than 2GB

Support and general discussion.
Post Reply
yochenhsieh
Posts: 6
Joined: Sun 22 Sep, 2019 12:39 am

v13-v15 problem with iso image larger than 2GB

Post by yochenhsieh » Sat 28 Sep, 2019 12:24 pm

Hello,
For pcem v13~v15 with guest os version win95, win95 osr2, win98se, if I want to mount a data-only iso image larger than 2x1024x1024x1024 bytes, it will be recognized incorrectly as audio cd in guest os system. The same image works fine in pcem v12 before.
I wonder if image handling was changed between v12-v13 and therefore caused such problem? Thanks.

User avatar
omarsis81
Posts: 713
Joined: Thu 17 Dec, 2015 6:20 pm

Re: v13-v15 problem with iso image larger than 2GB

Post by omarsis81 » Sat 28 Sep, 2019 4:41 pm

larger than 2gb means is not a CD image. DVD is not supported

User avatar
ppgrainbow
Posts: 467
Joined: Thu 04 Sep, 2014 7:03 am
Contact:

Re: v13-v15 problem with iso image larger than 2GB

Post by ppgrainbow » Sat 28 Sep, 2019 6:22 pm

The maximum size for a CD ISO image is 700 MB. PCem does not support DVD images at this time.

yochenhsieh
Posts: 6
Joined: Sun 22 Sep, 2019 12:39 am

Re: v13-v15 problem with iso image larger than 2GB

Post by yochenhsieh » Sun 29 Sep, 2019 12:01 am

So...
In pcem v12: Any size images are supported.
In pcem v13 and later: Only support image size smaller than 2GB.

Is above statement correct? Thank you.

User avatar
ppgrainbow
Posts: 467
Joined: Thu 04 Sep, 2014 7:03 am
Contact:

Re: v13-v15 problem with iso image larger than 2GB

Post by ppgrainbow » Sun 29 Sep, 2019 12:50 am

yochenhsieh wrote:
Sun 29 Sep, 2019 12:01 am
So...
In pcem v12: Any size images are supported.
In pcem v13 and later: Only support image size smaller than 2GB.

Is above statement correct? Thank you.
This statement is correct. A 700 MB CD-ROM ISO supports up to 360,000 sectors at 2 KB per sector for a total of 737,280,000 bytes in which it translates to 703⅛ MB of data with error correction. Perhaps PCem should limit the size of the CD-ROM ISOs to 703⅛ MB to probably prevent the emulator from incorrectly recognizing the CD-ROM ISO as a Audio CD since PCem has no support for DVD drives.

yochenhsieh
Posts: 6
Joined: Sun 22 Sep, 2019 12:39 am

Re: v13-v15 problem with iso image larger than 2GB

Post by yochenhsieh » Sun 29 Sep, 2019 2:41 am

Thank you very much for this clarification.:)

User avatar
ppgrainbow
Posts: 467
Joined: Thu 04 Sep, 2014 7:03 am
Contact:

Re: v13-v15 problem with iso image larger than 2GB

Post by ppgrainbow » Sun 29 Sep, 2019 3:13 am

yochenhsieh wrote:
Sun 29 Sep, 2019 2:41 am
Thank you very much for this clarification.:)
You're welcome. :)

yochenhsieh
Posts: 6
Joined: Sun 22 Sep, 2019 12:39 am

Re: v13-v15 problem with iso image larger than 2GB

Post by yochenhsieh » Sun 29 Sep, 2019 4:29 am

I think I'll need to keep some copies of v12 with different win9x os then. I have many large iso files for different purposes. If only v12 supports it, I'll stay on v12 for now. Still thanks for your response.

User avatar
ppgrainbow
Posts: 467
Joined: Thu 04 Sep, 2014 7:03 am
Contact:

Re: v13-v15 problem with iso image larger than 2GB

Post by ppgrainbow » Sun 29 Sep, 2019 4:34 am

PCem v12 is outdated and any issues related to that release won't get fixed as we're on v15 now. I'd stick with ISO less than 700 MB.

Cheez
Posts: 26
Joined: Tue 19 Dec, 2017 4:08 am

Re: v13-v15 problem with iso image larger than 2GB

Post by Cheez » Sun 29 Sep, 2019 2:30 pm

I'm not sure what's preventing you from making these "Data only" images into hard drive images and then mounting them that way with the secondary IDE. I don't know what exactly you're doing with them but it can't possibly require permanent use of a removable disc greater than CD size, hot swappable no less.

yochenhsieh
Posts: 6
Joined: Sun 22 Sep, 2019 12:39 am

Re: v13-v15 problem with iso image larger than 2GB

Post by yochenhsieh » Sun 29 Sep, 2019 2:49 pm

Because the programs only accept media data on a optical drive. Place the files on hard disk won't work. The original form was multiple cd-roms but I combined all data on one disc to prevent disc swapping.
http://gaming.trekcore.com/klingon/ (I combined 3 discs to 1)
http://gaming.trekcore.com/borg/ (I combined 3 discs to 1)
http://gaming.trekcore.com/encyclopedia/ (I combined with following content to 1 disc, this is larger than 2GB.)
http://gaming.trekcore.com/tngcompanion/
http://gaming.trekcore.com/ds9companion/

It's fine if it's no longer supported in PCem now, that's OK. I still have other alternatives to get them working. Only wondering why it used to work in v12 though.

User avatar
leilei
Posts: 685
Joined: Fri 25 Apr, 2014 4:47 pm

Re: v13-v15 problem with iso image larger than 2GB

Post by leilei » Mon 30 Sep, 2019 12:03 am

I've always seen the overly-large disc support as an unintentional happy accident if anything. DVDs were never supported. Also real-mode CD-ROM TSRs don't like large images either.

Post Reply