A2091 SCSI ram install

[melott]

Installing some ram to my A2091 SCSI card

I have the chips but I've checked the hardware sites
to see how it should be installed........

For 512K
For 1 meg

For 2 megs its obvious :-)

Mel

[davideo]

You need to set the Jumper 1 for the size of ram fitted. See picture here http://amiga.resource.cx/photos/a2091 the Jumper is on the top edge just in front of the 2 chips with labels stuck on them.

The ram chips are fitted in columns from the inside of the board outwards. 1st row = 512k, 1st and 2nd = 1Meg, all 4 columns full = 2Meg.

Hope that helps, Dave G 8-)

[melott]

davideo wrote:
You need to set the Jumper 1 for the size of ram fitted. See picture here http://amiga.resource.cx/photos/a2091 the Jumper is on the top edge just in front of the 2 chips with labels stuck on them.

The ram chips are fitted in columns from the inside of the board outwards. 1st row = 512k, 1st and 2nd = 1Meg, all 4 columns full = 2Meg.

Hope that helps, Dave G 8-)

...yes ... very much

Thanks

Mel

[chiark]

As Davideo says, start with the 4 sockets on the innermost bit of the card, and work out to the edge.  

For utter avoidance of any {bleep}-up potential, if you look at the top picture on http://amiga.resource.cx/photos/a2091

There's 16 ram chips on the left of that card.  You need to install chips in banks of 4, and they line up vertically from the rightmost sockets.

I know that's labouring the point, but wanted to make sure there was no ambiguity!

[davideo]

...yes ... very much

Thanks

Mel

You're welcome. Pleased I could help  8-)

[JimS]

Commodore's service notes recommend only using the 0 or 2MB settings. Seems there's a bug in the RAM autoconfig for the 2091 board. They say that if you must use the .5MB or 1MB settings, make sure the 2091 is in the first slot.. in rev4 & 6 motherboards, this is the one closest to the power supply.

-Jim

[melott]

JimS wrote:
Commodore's service notes recommend only using the 0 or 2MB settings. Seems there's a bug in the RAM autoconfig for the 2091 board. They say that if you must use the .5MB or 1MB settings, make sure the 2091 is in the first slot.. in rev4 & 6 motherboards, this is the one closest to the power supply.

-Jim

Would this problem have anything to do with earlier vs latest roms ?


Mel

[Jope]

The ROM has nothing to do with this.. It's more of a DMAC / Autoconfig logic issue.

[JimS]

melott wrote:
Would this problem have anything to do with earlier vs latest roms ?

As far as I know the main issue with the ROMS is drives bigger  than 1GB. You need the latest ROMS for those drives, even if you partition them. Got bit by that one myself. -Jim