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Reply 580 of 758, by VileR

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ripsaw8080 wrote:

That's mode 6? I wonder because you get 80-column text (hard to read in composite) unless you use some tweak (e.g. set mode 4 and switch to hi-res by writing to the CGA mode register, so you're in mode 4 as far as the video BIOS knows when drawing text).

It's mode 6, I just BLOADed screen data originally saved in mode 4 (thus the text).

Yeah, it's interesting about the different order - see also how the text is affected: when it's in black and white (which are on two opposite corners of the square), the edge artifacts will correspond to the other two corners (purple/green on the Apple, light blue/orange on the CGA).

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Reply 581 of 758, by NewRisingSun

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I never understood the Apple II's graphics modes until I standard emulating them. 😀 In doing so, I realized that all the Apple does is simply spit out video memory bit patterns as a black-and-white pixels (save for the half-shift bit in hires mode). Many of the idiosyncracies that Apple II graphics tutorials painfully try to explain are merely descriptions of the NTSC decoding process. The CGA's 640x200 composite color mode is basically the Apple IIe's double hires mode with more pixels (640 versus 560). In that sense, the CGA really did have better graphics than the Apple II, including the IIe, when connected to a TV.

Reply 582 of 758, by NewRisingSun

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I'm making good on an eleven-month-old promise to post better pictures of the Tandy 1000 TX's composite output. These are the same screens as before, only taken with a different camera. I've found that capture cards don't display the different blues in Blue Angel's menu background properly, whereas these off-CRT-TV pictures do.

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    Tandy1000_pictures_2.7z
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  • Filename
    Tandy1000_pictures_1.7z
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Reply 583 of 758, by NewRisingSun

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As has been pointed out before in this thread, the current "Super Boulder Dash" image is broken in that it does not work with machine=pcjr, depriving players of the enhanced graphics and sound. Having examined the image using the DosBox debugger, I have found the reason: The image contains four programs, the two games in PC and PCjr versions. All four are encrypted and decrypting upon loading. Someone decrypted the PC versions and NOPed out the decryption instruction but forgot to decrypt the PCjr versions as well. I have attached a program that patches the image (must be named DISK.IMA) to re-encrypt the PC versions and restore the decryption instruction.

Everything seems to run OK, except that I wonder why someone decrypted the PC program in the first place. It's possible that there might be some copy-protection left in the PCjr program, although I haven't noticed anything.

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    fixsbd.zip
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Reply 584 of 758, by HunterZ

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NewRisingSun wrote:

Everything seems to run OK, except that I wonder why someone decrypted the PC program in the first place. It's possible that there might be some copy-protection left in the PCjr program, although I haven't noticed anything.

People often stick to inferior versions/configurations of games if that's what they remember playing, or if they are too unfamiliar with other versions/configurations to be able to judge their merits.

Reply 585 of 758, by VileR

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Everything seems to run OK, except that I wonder why someone decrypted the PC program in the first place. It's possible that there might be some copy-protection left in the PCjr program, although I haven't noticed anything.

Appears to work perfectly here too - nice!

Thanks for those Tandy photos too; is that with your TV at full saturation? IIRC the problem with the captures was due to the two blues clipping when transformed to RGB.

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Reply 586 of 758, by Great Hierophant

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Thank you for fixing this game, the PCjr. version is amazingly superior compared with the PC/CGA version. The Tandy machine displays the PCjr.'s graphics and sound.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 587 of 758, by NewRisingSun

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HunterZ wrote:

People often stick to inferior versions/configurations of games if that's what they remember playing, or if they are too unfamiliar with other versions/configurations to be able to judge their merits.

I meant why did the unknown person bother to do any decrypting at all given that the game seems to work in its original encrypted form? I suspect the person did it in order to modify the PC programs in some way, although I have no idea to what end.

VileRancour wrote:

is that with your TV at full saturation?

It's at "default" saturation, meaning it neither adds nor subtracts from the saturation level being transmitted. At this setting, 640x200-based composite pictures are already oversaturated (because of the Tandy's low color burst amplitude used as an amplitude reference). The difference to capture cards and emulation is that on the TV, oversaturated colors don't drift off as simple R/G/B clipping would.

Reply 588 of 758, by Great Hierophant

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Do you think you can add a patch for the composite video selection to the PCjr. and Tandy 1000 modes, at least for the CGA-like modes? It seems that Seven Cities of Gold uses composite video for its graphics with PC/CGA and PCjr. (and does not appear to support Tandy). Right now you can have either superior composite color graphics with CGA or black & white graphics with superior 3-voice sound on PCjr. in DOSBox.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 589 of 758, by NewRisingSun

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Below the Root is affected by this as well. Future versions of DosBox should (with the monitor= config file entry) allow for composite video even in PCjr mode, given that we have already discussed the PCjr's composite output in this thread. I refuse to patch a game to compensate for a deficiency in current emulator versions.

Reply 590 of 758, by Great Hierophant

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I was not clear in what I sought, what I meant to ask for was to add composite color support for Tandy and PCjr. machine modes to the DOSBox composite video patch. However, to do so would probably mean adding it for the 16-color modes, (except for Tandy's 640x200x16 mode) even though 16-color composite video support was more of crutch for people who used TVs back in the 80s as their computer monitor. Can one reliably detect all ways in which a game can select a "CGA mode" with a PCjr or Tandy 1000 and limit composite color support to only those instances?

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 591 of 758, by NewRisingSun

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Great Hierophant wrote:

I was not clear in what I sought, what I meant to ask for was to add composite color support for Tandy and PCjr. machine modes to the DOSBox composite video patch.

That's what the "monitor=" patch is all about.

Great Hierophant wrote:

Can one reliably detect all ways in which a game can select a "CGA mode" with a PCjr or Tandy 1000 and limit composite color support to only those instances?

No, just as you cannot know whether any particular 320x200x4 mode picture is designed for an RGB or a Composite display, you cannot know whether a 640x200x2 composite mode picture is designed for the CGA old, CGA new, Tandy or PCjr composite output. The only thing known is that composite artifacting is never used for effect in text or 16-color graphics modes (unless you count "can you read the text below?" screens as "used for effect").

Last edited by NewRisingSun on 2013-04-20, 09:40. Edited 1 time in total.

Reply 592 of 758, by Great Hierophant

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Is the PCjr.'s composite color graphics output that much fuzzier than the CGA's? Compare the CGA and PCjr. screenshots of Below the Root : http://www.mobygames.com/game/below-the-root/screenshots

The CGA looks crisp but slightly washed out. The PCjr.'s are shifted to the right and while the colors very saturated, the details are much softer. The same person took both sets of screenshots and presumably the same capture hardware was used.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 594 of 758, by Great Hierophant

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It sounds like something best experienced in person. It also sounds like the PCjr. is closer to the old CGA when it comes to saturation and brightness.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 595 of 758, by VileR

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An optimal "monitor=" patch would simply use a single decoder and render composite video in 24-bit, so adding support for *all* PCjr, Tandy, and text modes would be trivial - all those 8-bit palette shenanigans (which currently are the limiting factor) wouldn't be needed.

4-color PCjr support shouldn't be that difficult to add to the current code; I was able to fake it well enough in CGA when experimenting with those Below the Root screenshots earlier in this thread - you just need to plug in the four palette entries and the additional 120-degree phase difference between the pixel clock and the color carrier. Though it still turned out to be a bit inaccurate, and for the sake of avoiding wasted effort I'd say this had better wait for an improved patch as above.

NewRisingSun wrote:

The only thing known is that composite artifacting is never used for effect in text or 16-color graphics modes

Never say never. 😉 I'm just starting to get interesting results from an idea I've had - watch this space...

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Reply 596 of 758, by NewRisingSun

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Having fixed Super Boulder Dash for PCjr support, I have looked at other Booter disk images that are supposed to have specialized PCjr support that somehow doesn't work with currently available images. So far I have found two: Oil's Well and BC's Quest for Tires (the latter only with the Composite monitor selection). Both images have bad sectors that are not used in PC mode but are read in PCjr mode, yielding only blocks of exclamation marks instead of the expected data. These games definitely need "re-dumping" from the original disks. Sadly, it seems that both titles are quite rare in their PC versions.

Reply 597 of 758, by Great Hierophant

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NewRisingSun wrote:

Having fixed Super Boulder Dash for PCjr support, I have looked at other Booter disk images that are supposed to have specialized PCjr support that somehow doesn't work with currently available images. So far I have found two: Oil's Well and BC's Quest for Tires (the latter only with the Composite monitor selection). Both images have bad sectors that are not used in PC mode but are read in PCjr mode, yielding only blocks of exclamation marks instead of the expected data. These games definitely need "re-dumping" from the original disks. Sadly, it seems that both titles are quite rare in their PC versions.

I and others really appreciated that fix, SBD really shines on the Jr/Tandy. Lets be grateful that OW and BC are Sierra titles and therefore have some notoriety.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 598 of 758, by NewRisingSun

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Having looked at Oil's Well and BC's Quest for Tires more closely, I am now certain that the data cannot be recovered without re-imaging another original disk. Of course, one could take the composite image data, convert the color numbers and just replace the missing PCjr image data that way, but that would defeat the purpose of using the PCjr versions in the first place.

If (when?) these disks are re-imaged, the original on-disk copy protection should be preserved as well. Oil's Well uses the regular copy protection scheme known from other 1984-1985 Sierra titles (very first version of COPYLOCK), as does the version of BC's Quest for Tires with the Sierra copyright that is currently only available as a DOS conversion. The version of BC's Quest for Tires with the Tandy copyright, which is on the aforementioned broken disk image, however uses a different copy protection method that expects a certain sector's data to change upon repeated reading attempts. This suggests a "weak bits" method being employed.

Reply 599 of 758, by Da_GPer

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NewRisingSun wrote:

Having fixed Super Boulder Dash for PCjr support, I have looked at other Booter disk images that are supposed to have specialized PCjr support that somehow doesn't work with currently available images. So far I have found two: Oil's Well and BC's Quest for Tires (the latter only with the Composite monitor selection). Both images have bad sectors that are not used in PC mode but are read in PCjr mode, yielding only blocks of exclamation marks instead of the expected data. These games definitely need "re-dumping" from the original disks. Sadly, it seems that both titles are quite rare in their PC versions.

Im sorry for necroing this subject, but I have a Tandy disk of BC's Quest For Tires and I want to redump it so Tandy mode can work properly. What programs do I need and how do I do it? If you need proof that I have the disk, I can show a pic.