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1 hour ago, WhataKowinkydink said:

This topic seems like a good place to mention this as it applies to both the 9938 and the F18A.  I was trying out the SMU Electrical Engineering Library on both the real hardware (with F18A and nanoPEB) and in MAME (using TI-99/4A EVPC) and noticed that I got similar behavior on both fronts - where the systems hangs on disk loading, and the SMU splash screen never appears.  At first (before trying MAME) is suspected the nanoPEB, but since it did the same thing with the 9938 EVPC, now I suspect it is the cartridge itself, somehow calling on something that the 9918 has that the 9938/F18A doesn't have. 

Are you using a cartridge with an original TI GROM or are you using an image in a simulated GROM cartridge? It is entirely possible that it is pulling something from the console GROMs that sets one of the VDP registers incorrectly.

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1 hour ago, Ksarul said:

Are you using a cartridge with an original TI GROM or are you using an image in a simulated GROM cartridge? It is entirely possible that it is pulling something from the console GROMs that sets one of the VDP registers incorrectly.

Great question - and I neglected to mention that detail: sorry about that.  I'm running the cartridge from FinalGROM.  However, that didn't occur to me since it works with a non-EVPC TI configuration in MAME (something else I should have mentioned though).

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29 minutes ago, WhataKowinkydink said:

Great question - and I neglected to mention that detail: sorry about that.  I'm running the cartridge from FinalGROM.  However, that didn't occur to me since it works with a non-EVPC TI configuration in MAME (something else I should have mentioned though).

Most likely, that points to an improperly set VDP register issue. You might be able to see where it goes off the rails using the Classic99 debug window.

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5 minutes ago, Ksarul said:

Most likely, that points to an improperly set VDP register issue. You might be able to see where it goes off the rails using the Classic99 debug window.

Thanks!  I was thinking of doing that I'm just not entirely sure what to look out for and it's been a while since I've used the C99 Debugger.  I'll go see what it does :)

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  • 2 years later...

I'm looking into adding V9938 support to JS99er. Is it correct that if you just drop in a V9938, the TI-99/4A start routine would set the VDP registers to values that produce garbage on the screen, so you need some kind of start-up cartridge or a system GROM modification to see the color bar screen?  

Edited by Asmusr
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1 hour ago, Asmusr said:

I'm looking into adding V9938 support to JS99er. Is it correct that if you just drop in a V9938, the TI-99/4A start routine would set the VDP registers to values that produce garbage on the screen, so you need some kind of start-up cartridge or a system GROM modification to see the color bar screen?  

I can send you the modifications you need to make console GROMs and ti basic work. There is not much you can hex edit it. The problem is the registers it set have the undefined bits at 1 instead of 0.

 

The second issue is the last free vdp ram spot in 8370 as to be move up a bit because if you write to vdp ram 3fff it causes it to automatically bank switch to next page.

 

These modifications were done with my SOB release which I included with my TIM.

 

I will send them to you later on as today I am on mobile and doing doctors appointments.

 

I recently did a simple grom 0 patched as well for usage as failsafe grom in my grommy2 as I have a v9938 installed in the PEB.

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13 hours ago, Gary from OPA said:

I can send you the modifications you need to make console GROMs and ti basic work. There is not much you can hex edit it. The problem is the registers it set have the undefined bits at 1 instead of 0.

Thanks, I found the VDP register data in TI-99/4A Intern in GROM 0 at >044C.

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13 hours ago, Gary from OPA said:

The second issue is the last free vdp ram spot in 8370 as to be move up a bit because if you write to vdp ram 3fff it causes it to automatically bank switch to next page.

But that's only in the 'new' modes, right?

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17 minutes ago, Gary from OPA said:

The intern book is based on earlier grom 0

 

You have screen vdp r1 at 44f

 

And then 8 vdp registers at 450 - r0 thru r7

Yes I also noticed that. Actually the values written to the 8 registers start at >0451: >00, >20, >F0, >0E, >F9, >86, >F8, >F7.

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1 hour ago, Asmusr said:

Yes I also noticed that. Actually the values written to the 8 registers start at >0451: >00, >20, >F0, >0E, >F9, >86, >F8, >F7.

Yes, 44f and 450 are screen on and off vdp/r1 and then you have 8 registers at 451.

 

All the undefined bits from the tms9918 manual for those 8 registers have to be set to 0 not 1 that sadly TI set the console grom to.

 

And the same has to be done to 3 bytes for TI Basic in grom 1 at 216c, as the basic interpreter sets up 3 vdp registers as well.Screenshot_20240914-043324.thumb.png.e4917ae1728a7fabc97c4c87c3519ecb.png

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2 hours ago, Asmusr said:

Yes, and I know what's wrong: I haven't implemented VDPWP and VDPWC yet!

Once you get more v9938 support working, a good test is my graphics demo, you can see the source released as well, tests out the various specific v9937 drawing and page commands and blinking and scrolling modes.

 

 

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12 hours ago, Gary from OPA said:

Once you get more v9938 support working, a good test is my graphics demo, you can see the source released as well, tests out the various specific v9937 drawing and page commands and blinking and scrolling modes.

Thanks, your graphics demo is working now.

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I have found very little software for the TI-99/4A that uses the V9938 G7 mode (256x192 in 256 colors from a fixed palette), so I made a new version of my old Monkey Island demo. (@InsaneMultitasker made something similar for the Geneve.) My version is on a 1 MiB cartridge, and should be work with the FinalGROM, but I don't have the hardware to test it. It works in Js99'er and MAME.

monkey-v9938.bin monkey-v9938.rpk

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  • 2 weeks later...
5 hours ago, publicarni said:

Thank you for Demo, 

but there is a problem with the pictures…

i use an evpc card…

IMG_0578.jpeg

Hmm, interesting. It's difficult from the photo to distinguish reflections and other issues arising from taking a picture of a CRT from the issue you describe. Is every second pixel column missing?

 

Has anyone else tried this on real hardware? Could it be overrunning the VDP?

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