Mega ST2 and booster

Problems with your machine in general.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10389
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: Mega ST2 and booster

Post by rubber_jonnie »

HigashiJun wrote: Wed Jul 14, 2021 3:01 pm
rubber_jonnie wrote: Wed Jul 14, 2021 9:30 am

With any booster I'd always recommend testing at the original CPU speed first. That way you can verify it is working under standard conditions.
And that is a wise recommendation...
:)
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...
User avatar
HigashiJun
Posts: 1177
Joined: Fri Jun 19, 2020 7:21 am
Location: Tokyo

Re: Mega ST2 and booster

Post by HigashiJun »

Ok, so tried the booster with the SEL pin connected to GND.

There is an improvement with the blitter, as it does not freeze the machine when enabled, but incredibly slows down the display of GEM windows.

When I manage to disable the blitter, everything goes back to normal.

The floppy disk drive is recognized and works great with no disk inserted in, but once I try to access a floppy, I have a row of bombs on the screen.
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 10389
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: Mega ST2 and booster

Post by rubber_jonnie »

Might be worth checking the Blitter pads with a microscope to make sure there aren't any solder whiskers shorting them.

Also, do you have a diag cartridge? I used one of these to help track down a floppy problem with a Mega, as it allows you to run tests repeatedly and consistently, something important when tracking down faults.

Has a couple of good Blitter tests as well as a suite of floppy tests. You may also want to test the RAM thoroughly.

I did some FDD repairs in this thread: https://www.exxosforum.co.uk/forum/viewt ... hilit=mega

Might help, worth a try, mine turned out to be the DMA that was giving the floppy problems.

One thing you didn't mention was if it all worked just fine before you did the upgrade? Also, does it work with the other version of TOS that's installed, which I am assuming is 1.04?
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...
User avatar
exxos
Site Admin
Site Admin
Posts: 23437
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Mega ST2 and booster

Post by exxos »

HigashiJun wrote: Thu Jul 15, 2021 6:13 am There is an improvement with the blitter, as it does not freeze the machine when enabled, but incredibly slows down the display of GEM windows.

When I manage to disable the blitter, everything goes back to normal.
That sounds really strange. I suggest you continuity check from the CPU to the blitter make sure there is not a bad connection somewhere.. Start with pin 10 of the CPU (DTACK) to pin 27 on the blitter.
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.
User avatar
HigashiJun
Posts: 1177
Joined: Fri Jun 19, 2020 7:21 am
Location: Tokyo

Re: Mega ST2 and booster

Post by HigashiJun »

rubber_jonnie wrote: Thu Jul 15, 2021 9:41 am One thing you didn't mention was if it all worked just fine before you did the upgrade? Also, does it work with the other version of TOS that's installed, which I am assuming is 1.04?
Everything is normal when I put back the original CPU (without blitter patch) and TOS 1.04.

FDD, Gortek or HXC work as expected, and blitter also works perfectly.

I made several loop tests with Gembench and there was no problem at all.

I only have those weird issues with the booster installed.
User avatar
HigashiJun
Posts: 1177
Joined: Fri Jun 19, 2020 7:21 am
Location: Tokyo

Re: Mega ST2 and booster

Post by HigashiJun »

exxos wrote: Thu Jul 15, 2021 9:46 am That sounds really strange. I suggest you continuity check from the CPU to the blitter make sure there is not a bad connection somewhere.. Start with pin 10 of the CPU (DTACK) to pin 27 on the blitter.
I wlll try the booster with the blitter patch on and also perform a continuity check tomorrow, as I am working today on my new STE board and your V1 plug-in booster... :D
User avatar
exxos
Site Admin
Site Admin
Posts: 23437
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Mega ST2 and booster

Post by exxos »

HigashiJun wrote: Thu Jul 15, 2021 11:10 am I wlll try the booster with the blitter patch on and also perform a continuity check tomorrow,
The blitter patch has never been attempted with the booster.. I don't know how it would even be fitted.. but with a recent blitter you don't need it...

See ATARI TECHNICAL NOTES ON THE BLiTTER

https://www.exxosforum.co.uk/atari/last/MEGAST/index.htm
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.
User avatar
HigashiJun
Posts: 1177
Joined: Fri Jun 19, 2020 7:21 am
Location: Tokyo

Re: Mega ST2 and booster

Post by HigashiJun »

exxos wrote: Thu Jul 15, 2021 11:29 am
HigashiJun wrote: Thu Jul 15, 2021 11:10 am I wlll try the booster with the blitter patch on and also perform a continuity check tomorrow,
The blitter patch has never been attempted with the booster.. I don't know how it would even be fitted.. but with a recent blitter you don't need it...

See ATARI TECHNICAL NOTES ON THE BLiTTER

https://www.exxosforum.co.uk/atari/last/MEGAST/index.htm
I read your interesting article some time ago and that is why I removed the blitter patch from my Mega ST.

I just want to test if only the blitter issue could be solved by adding the patch. I will not even solder it, just make it hold with some masking tape.
User avatar
exxos
Site Admin
Site Admin
Posts: 23437
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Mega ST2 and booster

Post by exxos »

HigashiJun wrote: Thu Jul 15, 2021 12:35 pm I will not even solder it, just make it hold with some masking tape.
That really does not sound like a good idea..

Does your machine work without the booster and without the blitter patch ?
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.
User avatar
HigashiJun
Posts: 1177
Joined: Fri Jun 19, 2020 7:21 am
Location: Tokyo

Re: Mega ST2 and booster

Post by HigashiJun »

exxos wrote: Thu Jul 15, 2021 1:07 pm
HigashiJun wrote: Thu Jul 15, 2021 12:35 pm I will not even solder it, just make it hold with some masking tape.
That really does not sound like a good idea..

Does your machine work without the booster and without the blitter patch ?
Could it be harmful for some components ?

The Mega works flawlessly without the booster and without the blitter patch.
Post Reply

Return to “HARDWARE ISSUES”