Problem with SCSI on TT

[Kroll]

Hi,

I have some problem with SCSI on Atari TT. This version Atari TT with board where SCSI controller is on the base. I got this controller from my friend who tested this controller on the other TT and it is OK, but when I put to my motherboard still not found any external and internal SCSI device connect to computer.

Some ideas what else can I check ?

Regards
Kroll

[frank.lukas]

Bus terminator set correctly ?

... once on the internal hard disk and once on the Atari TT Mainboard when no external hard drive is there .

See Termination -> http://en.wikipedia.org/wiki/Parallel_SCSI

[Kroll]

Hi

So if I understand correctly, I set the jumper "termination on" on my HDD, I have some SCSI HDD.
Where is the motherboard Atari TT switch on / off termination ?

Another thing that if I remember correctly it try to mount external device such as CD-ROM, a suitable terminator, but I can thoroughly test it tonight

Regards
Kroll

[frank.lukas]

The Resistor packs are the three red ones over the SCSI Chip .



… or Connecting an external SCSI Device and make sure it provide termpower to the Bus and it is terminated

[frank.lukas]

Termination on the Mainboard are the three resistor packs on the Board over the SCSI Chip ...

[Kroll]

HI,

thank you very much for your help.

At now when I connect external CD rom with terminator TT show on ID 5 this device. Nextly I found the hard disk and hddriver show on ID0 this hard disk, but I dont know why when I connect CD rom and HDD both It found only HDD.

The question is internal HDD and external CD-rom have it termination on both ?

Thank you very much for your help now Everything work perfectly. Thank you once again

Regards
Kroll

[lp]

The TT030 has a "T" style SCSI chain. This means the internal HD is one chain and the SCSI port on the back is the other. Both chains must be terminated. To clarify, the internal drive must be terminated. If you use the external SCSI port, removed the terminating resistor packs from the motherboard. If you do not use the external SCSI port, the terminating resistor packs should be left on the motherboard.

[Kroll]

Frank.lukas:

Could you do send me a link or picture the whole motherboard as described Atari TT. Here you can see only a piece of the motherboard

lp:
I want you use internal and external device both.
I understand that termination directly on internal hard disk (jumper)

Regards
Kroll

[frank.lukas]

Picture -> http://www.atari-computermuseum.de/pics ... /tt_mb.JPG

The Atari TT has no termpower for the internal (on the Bus) and external SCSI termination resistor …

Modify the SCSI Bus, on the PIN 25 from the external SCSI socket and PIN 26 from the internal SCSI socket
connect both with a cable and on there cable now comes via a diode and a 1 amp fuse 5 Volt …

5 Volt ->-Diode- -Fuse 1A- --- PIN 25 external SCSI socket
...............................................|__ PIN 26 internal SCSI socket

The ... are placeholder (does not mean anything)

Then you can put this on the external SCSI socket ...

[Cyprian]

Picture -> http://www.atari-computermuseum.de/pics ... /tt_mb.JPG

wow, that TT has the BLiTTER chip and has no the Shifter

[frank.lukas]

... this is wrong the Atari TT has no Blitter !

[frank.lukas]

Use the Google Translator -> http://phoenix.inf.upol.cz/~opichals/li ... &index=318

[lp]

Frank.lukas:

Could you do send me a link or picture the whole motherboard as described Atari TT. Here you can see only a piece of the motherboard

lp:
I want you use internal and external device both.
I understand that termination directly on internal hard disk (jumper)

Regards
Kroll

I only have this photo, its the back corner where the SCSI port is.
http://gfa.atari-users.net/TT030/img/battery_tt.jpg
Its the 3 red resister packs. Just remove them if they are there.

[wongck]

There is also a photo on our AF wiki page. photo link here
Shows 3 empty locations for the resistors

[Guest]

you dont need the resistor packs to test internal scsi
what i would do
as i just did to another members TT board and found two bad tracks under the socket
so i reworked the socket with a new one
the problem initially was a duff ic
failing to check for correct wire up continuity was the issue caused

so track all the connection on the scsi chip check for any shorts
using a digital meter set to diode range !! dont use buzzer or beep test ranges !!--->|---- diode only for chipsets
i use two needles and solder a pair of wires to them as test probes

you need to check that the dmac and the dcu are all connecting to the scsi chip
and that the rest of the data from the scsi chip and the unit control signals
are all connecting at the even pin numbers on the scsi port {no resistors in place}
do this with NO power

this diagram shows you what dcu and dmac to test {the scsi ones}

find the scsi dmac and dcu chips schematic sheet here
http://www.atariworld.org/files/docs/At ... ematic.pdf

page 10

also you will find that the scsi irq connects to MFP 2 pin 32 {from pin 26 of the scsi chip}

so i know its tedious but do it
youll find the reason pretty quick
the writing on some of the pins is bad
like the ready pin is pin 28 so the other signal is pin 26 but it looks like 28 etc

[Guest]

here is a helping hand with the pin to pin connections
for me this is easy to read fast in schematic
so

scsi irq connects to MFP 2 pin 32 from pin 26 of the scsi chip

DCU / DMAC TO SCSI CHIP CONNECTIONS

SCSI DMAC - SCSI CHIP

A1 pin 15 to pin 33
A2 pin 16 to pin 36
A3 pin 17 to pin 37
DRQ pin 73 to pin 25
EOP pin 76 to pin 30
DACK pin 77 to pin 29
RD pin 78 to pin 27
WR pin 79 to pin 32
CS pin 70 to pin 24
XRST pin 80 to pin 31

SCSI DCU - SCSI CHIP

ALSO CHECK PIN 6 SCSI DCU TO PIN 70 SCSI DMAC TO PIN 24 SCSI CHIP CS SIGNAL

D0.pin 51 to pin 2
D1.pin 52 to pin 44
D2.pin 53 to pin 43
D3.pin 54 to pin 42
D4.pin 55 to pin 41
D5.pin 56 to pin 40
D6.pin 57 to pin 39
D7.pin 58 to pin 38

SCSI CHIP TO 50 PIN PORT

P.....pin 11 to pin 18
ATN.pin 17 to pin 32
BSY.pin 15 to pin 36
ACK.pin 16 to pin 38
RST.pin 18 to pin 40
XSG.pin 21 to pin 42
SEL.pin 14 to pin 44
CD..pin 20 to pin 46
REQ.pin 22 to pin 48
IO...pin 19 to pin 50

PINS 10 - 3 ARE DB0 - DB7 AND GO TO
PINS 2,4,6,8,10,12,14,16

Rear DB25 to internal header
P.....pin 20 to pin 18
ATN.pin 17 to pin 32
BSY.pin 6 to pin 36
ACK.pin 5 to pin 38
RST.pin 4 to pin 40
XSG.pin 2 to pin 42
SEL.pin 19 to pin 44
CD..pin 15 to pin 46
REQ.pin 1 to pin 48
IO...pin 3 to pin 50


internal header PINS 2,4,6,8,10,12,14,16 = DB0 - DB7
and go to
external DB25 pins 8,21,22,10,23,11,12,13 : = DB0-DB7

[Guest]

i got a board from ebay for 82 euros + postage marked as defective
i also got three mice
the total was just under £100 uk
anyway it was marked as defective had a missing floppy controller ajax chip
and no scsi controller and its pads were in a very bad way
and no tos roms
there was just garbage on the screen black and white moving blocks <<note the word moving {tos loading}
so i pressed around and found that if i applied a little press to the mcu and powered on
it booted to a logo
so i reworked the mcu pins carefully with some flux liquid and hot air
you can resolder with an iron i just have a smd unit too use
so it then booted and didnt crash when i flexed the pcb a little

so i reworked the scsi port to a better starting state
and covered all areas except the area of the chip pads to avoid any solder issues or flakes of metal getting around
much like surgery

the 16/32 jumper was in the wrong location @ 16mhz fpu
fixing this too 32 the machine would not boot reliably

so i did the standard clock CLK32 clock to mpu/fpu and etc patch to u210 buffer chip and R888 REV h-k version
this board also had the clocks to the DMACs altered via another ic and up near to the mfp section
this is a factory mod
nice to know that if you mod the 32mhz clock to the mpu the machine is more relaible in 32mhz fpu mode
and this was wasnt i even changed out the fpu just incase so...mod the clock if its not done yet with your rev d-k
as you can see by the picture i posted
the mod is done a different way to the mpu clock j-k
so ill mod this one tomorrow the same was as the picture a few posts above via u210

i connected up thin wires to the under side of the plcc scsi socket i used
the plcc socket i removed the base plate from it by pressing it out with my thumb
so i could access the wires and pins etc below

so i patched it up then used the list above
i extended it a bit to include the external socket

so then i added a square of A4 paper cut to size to the inside of the socket
to avoid any shorting of the pins of the chip to other pads

so then !!!!
it worked lol !!!!!!!!

tested the floppy and hdd boot
all cool

so i can replace my duff board with bad funnels with a good one
ill do full cart tests on it tomorrow cant find it

[pilav]

@simbo2, thank you so much for taking the pain to write all the pin connections. I was actually looking for the pin connections for SCSI when I stumbled onto this thread and found the pin connections here to my surprise. Its funny how you sometimes find something you were so anxiously looking for in a place where you never expected it to be. It was so hard for me to just connect the 50-pin connector and now after reading this, I did it all within two hours. Thank you again.

[Guest]

@simbo2, thank you so much for taking the pain to write all the pin connections. I was actually looking for the pin connections for SCSI when I stumbled onto this thread and found the pin connections here to my surprise. Its funny how you sometimes find something you were so anxiously looking for in a place where you never expected it to be. It was so hard for me to just connect the 50-pin connector and now after reading this, I did it all within two hours. Thank you again.

no worries had too be done for the machine i did anyway...

perhaps ill add it too the guides section

if others can add the same pin to pin list then we are quids in too solving problems

glad you found it lets see if it actually fixed the issue you have also??

[qq1975b]

I didn't see this post when I had problems with my TT&SCSI disk. This is the link to that thread to avoid the same mistake...so now they're linked


http://www.atari-forum.com/viewtopic.ph ... 47#p267719

[Guest]

....

[qq1975b]

The TT030 has a "T" style SCSI chain. This means the internal HD is one chain and the SCSI port on the back is the other. Both chains must be terminated. To clarify, the internal drive must be terminated. If you use the external SCSI port, removed the terminating resistor packs from the motherboard. If you do not use the external SCSI port, the terminating resistor packs should be left on the motherboard.

So...If I want to use both (internal HDD and external CDROM) I have to remove the onboard resistors pack, right?
The same if I only want to use an external HDD/CDROM, but, if I want to use internal HDD, they must be left on board.

[wongck]

Look at the AF wiki http://www.atari-wiki.com/index.php/Ata ... _the_TT.3F

[Guest]

if you only use internal or only use external leave them there
if you use both internal and external then both the physical end device on the chain
should be terminated internal last drive on the cable external last drive

and you can remove them if you like but personaly i just leave them in place
then they dont get lost ,,, my house is full of bits ..

[qq1975b]

All clear now. Thanks