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Author Topic: OS3.2 Roms Installation  (Read 4846 times)

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Offline Castellen

Re: OS3.2 Roms Installation
« on: July 18, 2021, 04:06:40 AM »
I tried a quick sanity check using Blizkick to run the OS3.2 ROM image in a A3000D with CSmk2 060, it works fine.  Can't see any reason why the physical ROMs wouldn't work unless there was a problem with how they were written, or the two ROMs are exchanged.  The word-swapped EPROM binaries on the OS3.2 CD appear to be slightly mis-named, but the contents is correct otherwise.  i.e. if you recombine them and swap words, the resulting binary is the same as the A3000 ROM.

There's no harm in exchanging U180/U181 as there's a reasonable chance your physical ROMs have been mis-labeled.  So do give that a try, take care that pin 1 of the ROM matches that of the socket.

Shouldn't make any difference if the EPROMs are in a A3000T or A3000D.  The same ROMs should work in the A3000D, but you'll have to install them into the tower (adapter) PCB.

Unfortunately there's no easy way to tell if the ROMs have been written incorrectly without access to an EPROM programmer to check the contents of them.

A quick sanity check you can do is repeatedly press the caps lock key.  If the LED sticks (usually on) after 10 or so presses, it means the system isn't running at all; i.e. it's not reading in the keyboard serial data.  If the LED does turn on and off reliably, then the system is running (ROMs are working); though it's potentially waiting forever for scsi.device for some reason, or something else.

If you get stuck caps lock LED with the OS3.2 ROMs installed as you'd expect, or with U180/U181 positions exchanged, then there's most likely an issue with the data programmed into the EPROMs, in which case you'll need to return them.

In case you get stuck with the ROMs, send me a private message and I can put you in contact with someone local to you who can check the EPROM contents.
 
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Offline Castellen

Re: OS3.2 Roms Installation
« Reply #1 on: July 18, 2021, 08:26:06 PM »
So it was just a case of the two EPROMs being exchanged, an easy solution then.

I'd agree that it's confusing labelling the ROMs only as high/low, which relates to which 16-bit ROM forms the first or second half of the 32-bit data; as on most machines this detail doesn't appear on the board.  Printing the component designator (U180/U181) on the ROM label would eliminate any confusion as the same designators are used between A3000D/A3000T.

The purpose of the ROM tower was that on earlier variants of A3000D main board, rev. 7 and earlier as I recall, connections to the ROM sockets were for a different type of ROM that used a different pinout.  The tower just changes the connections to suit the more popular 27C400 style devices that have the +5V supply on pin 21.

The last revision and more common rev. 9 A3000D didn't need the ROM tower since connections to the U180/U181 sockets were changed to suit the 27C400 pinout.  That's also the purpose of the second pair of (unpopulated) 40-way ROM sockets on the A3000D, it's so that the other type of ROMs could be used if needed, although it almost never was.