apollo 4040 and A3000 scsi adaptor

[Pat the Cat]

If you mean the INT2 mod to bring that signal out to the CPU slot on an A3000, details here (good site for big box Amiga fixes);-

http://www.amiga.serveftp.net/A3000_INT2_mod.html

[Pat the Cat]

Well, originally you got an adaptor with the unit and had to stick one  of the Kicstart ROMs in it... translated from the manual... Be warned, the markings on A3000 motherboards may bear no relationship to what you have fitted. You want to pay attention to which end the notches are on chips before you start levering them out. They can be very tricky.

Locate the SCSI chip on the main board of your Amiga
3000. It bears the inscription WD33C93, Has a 40-pin DIL (dual-in-Line) housing and is located in the back of the computer
.
Now locate the kickstart ROMs. They are immediately there Next to the mouse and joystick connectors.

Now install the adapter sockets that are included with your Apollo 3040/3060 card. Leverage the SCSI chip WD33C93 Carefully with a wide screwdriver from its Base and insert it into the 'two - storey' base, which is the
inscription WD33C93 wearing. Make sure that the Marking notches of socket and SCSI chip.
Now carefully crank a Kickstart ROM (no matter which) Its base and
Plug it into the other socket, using the Kickstart ROM Is labeled. Now place the adapter bases with the chips in theCorresponding base on the main board. Pay attention to the correct polarity.

If you have purchased the Apollo 3040/3060 card with SCSI option to run SCSI devices,
Cable. Ensure correct polarity. Pin 1 of the cable is marked red, on the Apollo 3040/3060 board is a '1'.
Check again the position of the jumper 'SCSI', Which determines the Autoboot / Automount function.

Insert the drive carrier and turn back the screws (3 front, 2 rear).

If necessary, install your Zorro 2/3 expansion cards.

Close the housing cover, secure it with the screws provided and attach the cables to back to the computer housing

Perform a test run to ensure that everything is installed correctly. If your computer pauses while booting, check to see if The
68040.libraryFrom the Apollo Install disk to your boot partition.

If everything works as expected, you are done with the installation and are now owner (in) one of the fastest Amiga systems.

If your system does not start as expected, please refer to chapter 9...

...  I think I get why. Getting an A3000 to boot from a different controller  is no easy task. So I'm guessing the SCSI chip has to send a "go"  signal to the ROM chips, otherwise the processor can't access the ROMs to  begin working. If the first boot device is on the SCSI chain connected to an accelerator, that complicates matters. Plenty of people report complete failure with not having at least one SCSI device connected to an A3000 onboard SCSI controller. It is a minefield area.

Issue might date back to the first A3000s, and the  fact they loaded KS from Harddisk... so you NEEDED at least one drive  connected to the onboard SCSI for the kickstart file.

If I was to  pick ONE pin on the ROM... it would be chip select. That seems  sensible, it's the basic "Go chip, do your business" signal. Pins 10 and 12 (maybe both) are candidates, but you should really consult a datasheet on an ROM chip of that type if you haven't already.

The  other end, the SCSI chip, I'm not so sure of. Maybe SCSI select, I think  that's active low... You are have to be very careful experimenting with this  stuff. You want to make sure the connections aren't going to slip and  short out while you are busy turning computers on and off. Pin 39 is /REQ. Same deal, you have to check the datasheet of the chip.

[Pat the Cat]

Right, got some good answers I think.

First pic is the ROM for an A3000D. The peculiar thing about the early machines is, they could take A3000 sized ROMs, or A2000/A500 ROMs.

Second pic is the list of jumpers for an A3000, note the ROM timing jumpers, you might have to slow down access to the ROMs.

Third pic is a later model A4000, very similar to A3000. CBM just earthed pins 10 and 12 of all the EPROM chips, so making sure they were always available on the bus if needed. This is probably most fool proof way to do it, but might slow down accelerators or cause crashes if too quick or too slow jumper settings for ROM access speed.

Fourth pic is a set of A1200 ROMs. You don't want a set of these anywhere  near an A3000. They can be swapped around with a CD32 but... pretty much, the 2 are not that useful in the wrong machine.

Note the INTEL chips used by CBM engineers.

[Pat the Cat]

Oh right. Pin 9 is A0 line - so if that is always brought low, ROM cannot ever be accessed on odd byte boundary. Or other way around?

Still a little strange how the machine won't reset without that. I would have thought Pin 10 on the ROM more likely, makes it more like the A4000 which doesn't need the mod to use A3040 Apollo board.

[Pat the Cat]

I have a 4060 in my A3000 and it needs the patch. However, it doesn't boot with anything but the built in version 40.12 scsi.device

Hang on a moment... you can't boot with anything but the built in scsi.device. And you too have an a3000...

... CBM changed the A4000 ROM design, the one i posted early was the later model. Earlier ones look the like A3000, ROMEN connected to 12, but pin 10 is grounded. Later on CBM decided smarter to ground both of them as ROM nearly always remapped to 32 bit memory anyway.

This is the earlier A4000 ROM chip connections, much simpler, but not over simple like A3000.

I have tidied up the pictures, they were all blurry and totally unreadable. Sorry about that.

[Pat the Cat]

Got a plate full of issues myself right now, but I WILL get back to this...

... the reason I'm keen on it is, I used to be an A3000 owner. And I'm pretty sure I did work out how the internal boot disk could by bypassed, but that was about 20 years ago.

The reason I'm pretty sure is, I removed the internal boot disk after a long struggle (it was a dev machine with a Superkickstart) yet could still continue using the machine. It was an epic deal to work out how, I do remember that much,

I've still got the hard disk. The machine was stolen with a lot of other possessions. I must have booted the A3000 somehow.:confused: