Whats he deal with the Rom Tower?

[Cldrnbrn]

Hello.  I am new to the forum and have some questions about the Rom Towers on A3000's. I've done some googleing and searching various forums but can't get a straight answer.  I have 2 3000's that I was trying to combine to max out as much as possible.  Started out with a simple floppy drive swap from one but after that it wouldn't power up.  Ended up completely dismantleing both systems and swapping the zip ram from one to the other.  In the process I kinda broke the spacer on the tower but got the pins back in the right place and it looked ok.

1. what is the rom tower really used for?
2. do I actually need it?
3. why are there 4 rom slots on a motherboard but only 2 used for the rom tower?  what are the other 2 for?
4. If I use the tower what is the correct orientation?
5. I have a set of 3.1 roms I'm trying to install, so would I need the tower for that or can I plug directly into motherboard (my directions in the 3.1 kit I have tell me which sockets to plug them into (lower 2) but don't mention anything about a rom tower.

I know this is a lot and I'm sure it will just create more questions but I really appreciate it.

[countzero]

I'm not very well versed with the ways of the A3000, but recently I came into possession of one of those towers and did some research. it seems like the rom tower is for soft kicking the A3000 to kickstart 1.4. and it's possible to change this to soft kick another kickstart (by creating some special directories and stuff) but I forgot the exact procedure. The other two roms slots are for real A3000 roms (2.04 or 3.1).

rom tower is not necessary at all if you have 3.1 roms.

[alexh]

Cldrnbrn wrote:
1. what is the rom tower really used for?

Amiga ROMS have a fairly unusual pinout. At the time EPROMS with the same pinout as regular Amiga ROMS (e.g 27C400) were very expensive.

When developing KS2.0 there were many updates of KS ROM and to make things cheaper, early developer A3000's have ROM sockets which take standard pinout EPROMS.

A ROM tower converts regular pinout Amiga ROMS for use with these sockets.

Cldrnbrn wrote:
2. do I actually need it?

It depends. Later (Rev9) A3000's have normal ROM sockets and so A3000 ROMS came in two flavours. If you have one of these early (Rev7) A3000's and you have "regular" A3000 ROMS then you need a ROM tower to convert.

Cldrnbrn wrote:
3. why are there 4 rom slots on a motherboard but only 2 used for the rom tower?  what are the other 2 for?

I think they are for extended ROMS i.e. ones larger than 512kbyte, but dont quote me on that.

4. If I use the tower what is the correct orientation?

Unsure, but it will be obvious given the "notches" in the sockets and in the rom tower.

5. I have a set of 3.1 roms I'm trying to install, so would I need the tower for that or can I plug directly into motherboard?

Really depends on which type of ROMS they are and which A3000 you have. If you have anything other than a Rev7 motherboard, chances are you need a ROM tower.

There is a picture of a ROM TOWER and the "special" ROMS on the A3000 page on BBoAH (http://www.amiga-hardware.com)

The problem with using a ROM tower is that an AmiFast ZiptoSIMM converter wont fit. If you have fully populated ZIPRAM (16Mbyte) then it is not a problem.

[Borkmaster]

My understanding is that early revision A3000 motherboards used ROM sockets that were wired for EEPROM chips, not permanent mask ROM chips normally as used in other models.

The ROM tower had a passthrough for EEPROM chips (center two modules) and proper crosswiring for mask ROM chips (outer two modules).

Later motherboard revisions had ROM sockets that were compatible only with the mask ROM chips.

If your ROM tower is damaged or missing, you could transfer your Kickstart images to proper EEPROM chips.  However, this is somewhat difficult given that Commodore split the ROMs into two chips (high order and low order).  Not many EEPROM programmers can handle this.

Cldrnbrn wrote:
Hello.  I am new to the forum and have some questions about the Rom Towers on A3000's. I've done some googleing and searching various forums but can't get a straight answer.  I have 2 3000's that I was trying to combine to max out as much as possible.  Started out with a simple floppy drive swap from one but after that it wouldn't power up.  Ended up completely dismantleing both systems and swapping the zip ram from one to the other.  In the process I kinda broke the spacer on the tower but got the pins back in the right place and it looked ok.

1. what is the rom tower really used for?
2. do I actually need it?
3. why are there 4 rom slots on a motherboard but only 2 used for the rom tower?  what are the other 2 for?
4. If I use the tower what is the correct orientation?
5. I have a set of 3.1 roms I'm trying to install, so would I need the tower for that or can I plug directly into motherboard (my directions in the 3.1 kit I have tell me which sockets to plug them into (lower 2) but don't mention anything about a rom tower.

I know this is a lot and I'm sure it will just create more questions but I really appreciate it.

[alexh]

Borkmaster wrote:
My understanding is that early revision A3000 motherboards used ROM sockets that were wired for EEPROM chips, not permanent mask ROM chips normally as used in other models.

That's what I just said, but they were for cheap EPROM's in general. Not necessarily EEPROMS. It was all down to the pricing of the 27C400 chips I feel (EPROMS with Amiga MASK ROM pinout).

Commodore split the ROMs into two chips (high order and low order).  Not many EEPROM programmers can handle this.

I dont think this is true. All EPROM programmers that I have ever used, the software has supported 32-bit data, 16-bit EPROMS (i.e. splitting data). And I've used a LOT.