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Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: theOldSport] #102223 10/25/15 10:10 PM
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After seeing those side-by-side I think our existing monochrome-with-emphasis palette is *way* too subtle.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: R. Belmont] #102224 10/25/15 11:19 PM
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Perhaps it differs from system to system? But you're right, it's not very noticeable in MESS. It seems like a simple tweak though.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: theOldSport] #102226 10/25/15 11:35 PM
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The MAME screenshot has emphasis?

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: Octocontrabass] #102228 10/25/15 11:53 PM
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Just barely, it seems. However, on the actual hardware, contrast and brightness can be manually changed on both the Osborne-1 and its external monitor. In the picture I took, contrast and brightness were maxed.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: theOldSport] #102231 10/26/15 08:55 AM
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OK, I kinda see how it woks now. The Screen-Pac maintains a shadow of character and attribute memory. It takes clock signals off the main board and uses the 1MHz character clock from the main board to feed counters to step the character position.

There are two bits that it uses for control. One of them HC-LEFT appears to control the horizontal origin of the display. The other H=52/H=100 controls whether it uses its feeds its own address to the character generator ROM or the one from the main board's circuitry.

It appears to take H=52/H=100 and HC-LEFT from the low two bits on the data bus when A10 is high, A11 is low, /IOSEL is low, and the CPU is making a write request. Not being an Osborne expert, I have no clue what this means, but I presume it's reacting to the address used to control horizontal scrolling in low resolution mode.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: R. Belmont] #102234 10/26/15 02:10 PM
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Originally Posted By R. Belmont
After seeing those side-by-side I think our existing monochrome-with-emphasis palette is *way* too subtle.

The trouble is, from the schematics our monochrome-with-emphasis is correct assuming the monitor has linear gamma. Actually getting monitor gamma right would be difficult.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: theOldSport] #102235 10/26/15 02:22 PM
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Preliminary support for SCREEN-PAC has been added. You can choose between standard and SCREEN-PAC video in Machine Configuration through the internal UI (tab menu in partial keyboard mode). The utilities disk correctly detects the presence or absence of the SCREEN-PAC. 104-column text displays correctly. 80-column mode is probably completely broken. Scrolling in 80-column and 104-column modes probably doesn't work properly. Is there a test program for exercising the screen modes with reference output?

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: theOldSport] #102236 10/26/15 02:32 PM
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The trouble is, from the schematics our monochrome-with-emphasis is correct assuming the monitor has linear gamma.

Isn't CRT gamma exponential?

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: Vas Crabb] #102247 10/26/15 09:30 PM
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Originally Posted By Vas Crabb
Is there a test program for exercising the screen modes with reference output?

I am not aware of any test programs. Perhaps the original core's authors have something like that, though I kinda doubt it. Unless by a test program you mean an Osborne-1 program? If you need a reference, I could compare it to the original hardware (if that's what you mean).

Here's a test showing how WordStar 3.3 boots on my Osborne-1 (with Screen-Pac installed)-
https://drive.google.com/file/d/0Bw1m9gdt8DfpdDJsRU1Tazg2N28/view?usp=sharing
When turned on, it remains on the default 52-column mode, but when it runs the 80/104-configured WordStar program, it shifts into the new text mode.

And here's a test showing how the scroll function is altered by the higher text mode-
https://drive.google.com/file/d/0Bw1m9gdt8DfpNjh5UUhaaG1nRDQ/view?usp=sharing
It is much less precise (pretty choppy, actually) in 80/104 text modes.

In both tests, the Osborne-1's built in monitor is uselessly glitched (only in higher text modes), so an external one must be used.
It would be great if someone could confirm the scroll lag and text glitches on another working system.

Re: Osborne-1 "Screen-Pac" Emulation, 80/104-columns [Re: Vas Crabb] #102251 10/27/15 04:37 AM
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So I tested your new commit with a modified (104-column default) SuperCalc 2 image, and you are correct for the most part. Here's a copy of the diskette- https://drive.google.com/file/d/0Bw1m9gdt8DfpOFNVMkNvdTNXZUE/view?usp=sharing

The 52-column mode seems to still work fine, with no new scrolling issues. It correctly shows columns A-E completely.


The 80-column mode shows the same result as the 104-column mode, though scrolling doesn't seem any different. It incorrectly shows columns A-K, while it should show A-J.


The 104-column mode correctly shows columns A-K completely. Again, I didn't notice any new scrolling issues.


Thank you for your work thus far! On a sidenote, there is a strange "stepping" issue I've noticed when scrolling. This already occurred before your commit, but I think it's important to note. Naturally, this does not occur on the original system. Here's a video of it-
https://drive.google.com/file/d/0Bw1m9gdt8DfpeWJnMFd4RDRZY00/view?usp=sharing

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