Hey all, I've got a new MEGA ST2 here and I've gone through all of the mandatory fixes (DMA pullups, 2.2k bus resistors, etc) and I've still got an issue I've not seen before.
During boot, I get a bunch of unexpected characters on the screen as text is displayed. I also see similar behavior with running YAART from the cartridge port, although YAART itself runs through multiple cycles with no errors.
I'm running an Exxos PSU, and I've also swapped out the TOS ROMs to 1.4 but saw no change.
What's interesting here is that the "random" characters don't really change, it's pretty-much always the same thing in the same places. I found some dodgy solder joints on the shifter and got those sorted, but I haven't really noticed any graphical issues. (This is the MEGA ST2 with the Genlock that I posted about, but this happens with or without the Genlock attached)
One unfortunate thing is that I don't have a mouse/keyboard quite worked out yet, but it never seems to have issues booting to the GEM desktop, and once there everything always seems to be displayed properly (I've got a working prototype clone I built of an Eiffel hooked up to another ST that I need to transplant to get kb/mouse input working)
Any ideas where to look next?
MEGA ST2 - "random" characters on the screen
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Re: MEGA ST2 - "random" characters on the screen
Does it have a blitter / blitter patch ?
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: MEGA ST2 - "random" characters on the screen
It's got a blitter but no blitter patch - I *believe* the date code here means this one should be okay without it, but I could rig one up to test - I think I have the parts here.
I've got another blitter I can swap in as well from a 1040STF (which works fine with no patch) if that would be worth a shot.
Here's what I've got (I removed the retaining clip from the blitter to take this photo)
Re: MEGA ST2 - "random" characters on the screen
8831 in my notes (bottom of page) https://www.exxosforum.co.uk/atari/last/MEGAST/index.htm says 8822 should be fine.. but as its close to both.. those dates on my site may not be 100% correct..DominoTree wrote: ↑Wed Feb 03, 2021 9:28 pm It's got a blitter but no blitter patch - I *believe* the date code here means this one should be okay without it, but I could rig one up to test - I think I have the parts here.
Might be easier just to remove the blitter and solder the 2 blobs and test without it...
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: MEGA ST2 - "random" characters on the screen
Gave it a try with no blitter and it's still the same (with the same characters in the same places)exxos wrote: ↑Wed Feb 03, 2021 9:32 pm8831 in my notes (bottom of page) https://www.exxosforum.co.uk/atari/last/MEGAST/index.htm says 8822 should be fine.. but as its close to both.. those dates on my site may not be 100% correct..DominoTree wrote: ↑Wed Feb 03, 2021 9:28 pm It's got a blitter but no blitter patch - I *believe* the date code here means this one should be okay without it, but I could rig one up to test - I think I have the parts here.
Might be easier just to remove the blitter and solder the 2 blobs and test without it...
- rubber_jonnie
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Re: MEGA ST2 - "random" characters on the screen
I did also reply on FB as I saw it there first (Should really check here first!), but it looks like you have quite a few things loading in at boot time, including a font cache program.
I'd suggest you boot with just the hard disk driver and see if the problem happens, and if not. then slowly add in your other boot time programs one by one to see if a specific program is causing the issue.
I don't believe it's some kind of stuck key event as you said on FB you don't have a keyboard at the moment, or you'd see more characters. If you you don't have a keyboard coming and need a keyboard solution I'd recommend an Eiffel from Gossuin.be.
I'd also suggest before using your good SD card/Ultrasatan on an unknown machine that you back up your card first. I've had unknown machines corrupt my SD cards before the mandatory fixes were done, so it's simple to have an image you can just re-write to the SD if it all goes wrong. If you're using Windows, I'd suggest Win32DiskImager.
I'd suggest you boot with just the hard disk driver and see if the problem happens, and if not. then slowly add in your other boot time programs one by one to see if a specific program is causing the issue.
I don't believe it's some kind of stuck key event as you said on FB you don't have a keyboard at the moment, or you'd see more characters. If you you don't have a keyboard coming and need a keyboard solution I'd recommend an Eiffel from Gossuin.be.
I'd also suggest before using your good SD card/Ultrasatan on an unknown machine that you back up your card first. I've had unknown machines corrupt my SD cards before the mandatory fixes were done, so it's simple to have an image you can just re-write to the SD if it all goes wrong. If you're using Windows, I'd suggest Win32DiskImager.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: MEGA ST2 - "random" characters on the screen
It does the same thing without the hard disk attached, booting from cartridge, so it's not something being loaded at boot.rubber_jonnie wrote: ↑Thu Feb 04, 2021 9:22 am I did also reply on FB as I saw it there first (Should really check here first!), but it looks like you have quite a few things loading in at boot time, including a font cache program.
I'd suggest you boot with just the hard disk driver and see if the problem happens, and if not. then slowly add in your other boot time programs one by one to see if a specific program is causing the issue.
I don't believe it's some kind of stuck key event as you said on FB you don't have a keyboard at the moment, or you'd see more characters. If you you don't have a keyboard coming and need a keyboard solution I'd recommend an Eiffel from Gossuin.be.
I'd also suggest before using your good SD card/Ultrasatan on an unknown machine that you back up your card first. I've had unknown machines corrupt my SD cards before the mandatory fixes were done, so it's simple to have an image you can just re-write to the SD if it all goes wrong. If you're using Windows, I'd suggest Win32DiskImager.
I've got a microcontroller-based prototype that should work to give me kb/mouse, I just haven't taken the time to wire it to the MEGA yet (it's currently handling input for an STF)
Got plenty of backups floating around here too
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Re: MEGA ST2 - "random" characters on the screen
Tried with another known good DMA, another known good GLUE, another known good MMU, another known good shifter, and with/without blitter (two different ones) and it's still doing the same thing. Guess this is gonna get really interesting
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Re: MEGA ST2 - "random" characters on the screen
Could it be some sort of IKBD controller error?
Re: MEGA ST2 - "random" characters on the screen
That sounds like pullup problems, id check all the address and databus on CPU to make sure you have 2.2K on them all...DominoTree wrote: ↑Wed Feb 03, 2021 9:22 pm During boot, I get a bunch of unexpected characters on the screen as text is displayed. I also see similar behavior with running YAART from the cartridge port, although YAART itself runs through multiple cycles with no errors.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.