Blitter issues on a Mega STE

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Bikerbob
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Blitter issues on a Mega STE

Postby Bikerbob » Tue Nov 21, 2017 6:36 pm

Hello all,

I have been working through my issues on my Mega STEs. I have an older one.. like the one troed has been working on. First 10k of boards made.

It does look like the Floppy has been upgraded at some point - PAL -2 is in. Outside of the board being old. it seems to work well. I have 1 spot where a transistor under the psu looks to have been damaged and was "wired" on.. I want to fix that.. but otherwise it is booting, and everything I have tried so far is working.

The other is newer and is having a Blitter issue, in that if I click on the blitter in the options menu, it locks up the machine.

I dont have a diag cart, but maybe that is the way to go at this point for that computer?

My plan is to have one as my main machine, and maybe get the other into a "good" state, and sell it. Anyone have any trouble shooting tips?

Also I am trying to put on 2.06 US on the machines, I used PPs rom splitting software on a 206 US img. But burning the HI rom has been a bugger, I keep getting an error in the same location the same issue... I have programmed and erased the chip 6 times already.

James

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Re: Blitter issues on a Mega STE

Postby Bikerbob » Sat Nov 25, 2017 1:19 pm

So, if you were not aware, the actual Blitter chip is just in front of the VME under the RH cable on the Mega STE. I am going to pull it clean and re-seat today, see if that does anything, otherwise, from the diagnostic manual that would go with the cart - which I dont have, it says if the blitter tests fail, and I would assume trying to activate the blitter a blitter test ;) that you are to check the jumpers - I FIND NO JUMPERS associated with the blitter, I am wondering if in a prototype MSTE you could have had one shipped without it??? or replace the blitter, so I need to find one. Anyone with an extra????

James

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Re: Blitter issues on a Mega STE

Postby Bikerbob » Sun Nov 26, 2017 12:01 pm

So, did find the "jumpers" they were R504 and R505 on the board just in front of the Blitter. Interesting that if you have a blitter they are supposed to be empty ,but on the really old board they were very high 41K resistors, which means about the same.. but at some point they just removed them period.

SO, a pull (I have a proper puller) and clean the chip and socket with ISOpropo and we are back in business with the blitter, it is a non atari blitter btw, the kind that exxos sells, so, wonder if this machine has had issues with a blitter in the past, or on later boards they were using generic blitters.

James

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Re: Blitter issues on a Mega STE

Postby troed » Sun Nov 26, 2017 12:25 pm

R224 and R225, right?

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Re: Blitter issues on a Mega STE

Postby czietz » Sun Nov 26, 2017 12:35 pm

What is a "non Atari Blitter", BTW?

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Re: Blitter issues on a Mega STE

Postby AtariZoll » Sun Nov 26, 2017 12:43 pm

Bikerbob wrote:...
SO, a pull (I have a proper puller) and clean the chip and socket with ISOpropo and we are back in business with the blitter, it is a non atari blitter btw, the kind that exxos sells, so, wonder if this machine has had issues with a blitter in the past, or on later boards they were using generic blitters.
James

I don't think that Mega STE-s were shipped without blitter, since it was introduced 2 years earlier.

Considering EPROM programming - I guess that you should try another EPROM chip. Or maybe just to erase it little longer. Really, there is no such ROM content what is bugger - there are only 0-s and 1-s everywhere, and every combination (there is 2 power 1048576 of them :D ) can be programmed in EPROM without problem, when all is OK - EPROM and programmer device + PSU for it if needed.
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Re: Blitter issues on a Mega STE

Postby Bikerbob » Sun Nov 26, 2017 5:05 pm

troed wrote:R224 and R225, right?


Yes Troed, was late.. was going on memory.

James

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Re: Blitter issues on a Mega STE

Postby Bikerbob » Thu Nov 30, 2017 2:57 am

czietz wrote:What is a "non Atari Blitter", BTW?



Yes it was,

Pulled cleaned and the socket cleaned with Isopropo and we are back in business :)

James

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Re: Blitter issues on a Mega STE

Postby AtariZoll » Thu Nov 30, 2017 7:57 am

I think that some mocking was in that question. You come with words: "non Atari', 'generic' blitter. Honestly, it makes me smile. If you meant some diverse versions of it, that would make sense. What I know is that diverse chip manufacturers made custom chips for Atari ST serial. So, you may see diverse writings on them, but they are practically same, done by same design.
And you still own proper reply on question "What is a "non Atari Blitter", BTW?" - Saying 'it was' is not proper answer. He asked what you consider as such.
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Re: Blitter issues on a Mega STE

Postby czietz » Thu Nov 30, 2017 6:39 pm

Yes, that's what I meant. Like AtariZoll said, there were different manufacturers of Blitters (I know of ST, IMP, NS and RCA/GE) but all of them were made specifically for Atari and according to Atari's design specs. So, there is no "generic Blitter". Still I'm interested in which one you have, Bikerbob.

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More on my Mega STEs

Postby Bikerbob » Thu Dec 07, 2017 1:31 am

Ok, continuing on with my Mega STEs

Both have new batteries for the RTC.. Does the mega STE still have a Y2K issue? Do you use a little program? aka the one that will only be good to 2019? then what do we do?

I have a Cosmos - it gets time from an npt server and changes the date.. IS that bypassing the Y2K? If I set it and the battery is good.. does it stay?

moving on..

Everything else in the machine seems to be ok, I now have TOS on one machine upgraded to 2.06 US - this will stay, the other is getting a 4mb tos chip and I am installing a 4 way tos into that one.

Floppy - not been having luck with the 1.44 - both machines have the GAL with the -02 the -02-02 controller or Ajax (1 of ea) and both have the 7th dip switch up.. (Both came to me this way) The SMD-340 I got is a bad read most of the time, the one I bought was DOA.. I have a couple of Sony MFP920 drives, I have done the SEL0 mod on one.. it works, but only as a DD drive.. I thought with everything above it was just supposed to work in the mega ste.

Anyone?

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Re: Blitter issues on a Mega STE

Postby AtariZoll » Thu Dec 07, 2017 7:46 am

There are some differences between Atari ST, TT, Falcon compatible floppy drives and those which were sold after ST era. You need to look pin layouts, understand what is for what, etc. Then reconnect some pins by need. There is no general solution for all possible drives.
And, I don't think that it is worth of all hassle. What you will do with HD floppies ? Get mass storage - pardon, you already have one. There is no SW for Mega STE what requires HD floppy run.
I say that floppies are at their end now, even in case of retro computers. There is just too much problem with them - with drives, disks, and will be only worse an worse. Some HW floppy emulator is the way, known way over years.
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