Atari TT internal scsi questions?

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Oldskool
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Atari TT internal scsi questions?

Postby Oldskool » Tue Mar 01, 2016 9:27 pm

Dear All,

Just received my first Atari TT. I tried connecting an internal scsi drive (scsi2sd).
Scsi id is set on 0 (which is default I think for the TT).
When I boot with hddriver it hangs on scsi 0 (hddriver message when booting).
So it sees something but something is wrong in the communication.
I opened the TT and I found that the sockets for the termination are empty.


I have two questions:
1. Can somebody confirm that my issue is due to the missing termination on the PCB?
2. Where can I get these termination resistor packs?

I hope to hear from you.

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wongck
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Re: Atari TT internal scsi questions?

Postby wongck » Tue Mar 01, 2016 10:50 pm

May be something in the atari forum wiki may help?
http://www.atari-wiki.com/index.php/Atari_Forum_TT_FAQ
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lp
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Re: Atari TT internal scsi questions?

Postby lp » Wed Mar 02, 2016 12:53 am

My TT030 was never to picky about the ones on the motherboard missing. Are you positive the internal drive is terminated? If it isn't, that could be the problem. The internal drive itself must be terminated.
Last edited by lp on Mon May 14, 2018 6:04 pm, edited 1 time in total.

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SoundDoctor
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Re: Atari TT internal scsi questions?

Postby SoundDoctor » Wed Mar 02, 2016 2:28 am

There are two versions of the SCSI2SD - the older one has to be jumpered to self power the onboard resistors if the SCSI bus provides no term power (the TT doesn't). The newer one doesn't need to be jumpered to provide term power to itself. Which version of SCSI2SD do you have, the v5.0 or the earlier revision?

Word has it that the SCSI behaviour on the TT is very dependent on the Rev of the motherboard. There was a lot of rework on the SCSI circuits between the early and later revisions. Mine is a Rev H board and it seems not to care too much whether or not the terminating resistors on the motherboard are fitted. Well, sort of.
When I got it there were none fitted internally but I had no problems with the internal SCSI drive (terminated), just like lp's machine. However, I thought it would be a good idea to terminate the TT / external bus as per the 'rules'. I didn't have any resistor packs so I fitted an external passive terminator. Big problems (of course the TT supplies no term power over the D25 so fitting the terminator to the external branch of the T should have made no difference, but it did -internal drive not happy). Then I tried to use an external SCSI device (also terminated), again I had big problems until I enabled self term power on the external drive. Eventually I got some resistor packs and went ahead and fitted them anyway just for sh*ts and giggles. Now, my external (terminated) device and internal (terminated) drive were still happy. This makes no sense.
With the motherboard terminators fitted and external and internal drives both terminated all drives were happy. Without the motherboard terminators fitted, internal and external drives were very picky when both busses were connected, either a drive or a passive terminator. With no motherboard resistors fitted and only external (terminated) or internal (terminated) drive connected either drive was happy. This behaviour is the complete reverse of what I would have expected. My SCSI busses appear quiet no matter what without the resistor packs fitted but with the terminators fitted they seem ring like church bells after a wedding - Go figure.
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Oldskool
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Re: Atari TT internal scsi questions?

Postby Oldskool » Wed Mar 02, 2016 7:53 pm

Hello,

Thanks for the tips and help!
The atari TT does not have a rev number. On the PCB I see rev ....
So probably the first rev? (its 33 mhz but most ic are in sockets and it has a big metal shielding)
The scsi2sd is a version 3. Yesterday I already tried with a jumper on the board.
Today I tried some other microsd's. It now seems to work.
So yesterday it was a combination of no jumper and an incompatible microsd.

Thanks for the help.

I'm very happy now. Always a bit of a gamble buying these things. The TT is in a very bad shape. So will take some time to get it in top condition again. But this is a first step.

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Re: Atari TT internal scsi questions?

Postby paul92706 » Mon May 14, 2018 2:46 pm

Oldskool wrote:Hello,

Thanks for the tips and help!
The atari TT does not have a rev number. On the PCB I see rev ....
So probably the first rev? (its 33 mhz but most ic are in sockets and it has a big metal shielding)
The scsi2sd is a version 3. Yesterday I already tried with a jumper on the board.
Today I tried some other microsd's. It now seems to work.
So yesterday it was a combination of no jumper and an incompatible microsd.

Thanks for the help.

I'm very happy now. Always a bit of a gamble buying these things. The TT is in a very bad shape. So will take some time to get it in top condition again. But this is a first step.


Hi old skool, can you please state the brand model of microsd you used? i am having same problem with my scsisd hanging!
Atari Falcon CT60/CTPCI 14MB+ 512mb ATI9250 + NetUSBee
Atari Falcon030 CF 4gb + NetUSBee+ 14MB Ram
Atari TT030 2meg STRAM/16meg TTRAM + Nova Adaptor +Maxtor SCSI HD + DaynaPort Pocket SCSI


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