SupraDrive 500XP + Trapdoor ram problem

[dougal]

Yesterday I got an A500 which came with a SupraDrive 500XP and a 2MB trapdoor expansion.

With the trapdoor ram enabled the HDD does not boot or even be seen.

As soon as I disable the trapdoor you can hear the HDD working and it works perfectly.

The SupraDrive has 4MB ram inside it. That works correctly both with the trapdoor ram enabled and also disabled.

I also tried it in my A500+ which has a 1MB expansion (Total 2MB chipram) and had the same issue. Can see 2mb chip and 4mb fast but no HDD.

Disable the trapdoor ram and the HDD works.

I don't know if its worth noting but I do NOT have the optional PSU for the Supra.

Also worth noting that I am using the same PSU that I use for my A1200 which has a Blizzard 1230IV and HDD. Its an A500 heavy PSU, so it should be good enough.

[Oldsmobile_Mike]

The hard drive doesn't spin at all with the trapdoor ram enabled?  Completely silent?  Doesn't show in Early Startup screen? Could be some bizarre address conflict?

A1200 probably uses a 2.5" hard drive.  SupraDrive probably uses a 3.5" drive.  Much bigger, higher power draw, yadda yadda.

A500 can power a drive through the side connector, as you've seen and as evidenced by these mods (which I've done on mine), but if it were me, personally, I wouldn't run a high draw mechanical drive that way.  Look for a CF or SD adapter, instead.  Just .02 cents.

Possible to try the 500XP with a different, smaller drive?  Or one with a lower power draw?

[dougal]

The HDD spins up with the trapdoor expansion in, but it doesn't make the reading clicking sounds of the self test as it does when the trapdoor ram is disabled.

I don't have any spare SCSI drives to test.

As far as I've read on Amigaresource the power supply for the supradrive is optional but on the manual it states that it is included. So conflict there.

In any case I don't have an external power brick for it unless I can use the same one of the CD32 or A590.

[Tenacious]

My vote would be the addressing conflict.

The A500 is not an A500+, right?  What is the make of this 2MB trapdoor expansion?  It can't be mapped entirely as CHIP because the 512K on the motherboard begins that address space. 2MB is the maximum CHIP ram addressable on any classic Amiga.

I wonder if both the new A500 with 2 MB trapdoor AND your existing A500+ conflict with the address point of Supra's HDD controller.   I don't recall if the 500XP is even compatible with the A500+.

Can you put a normal 512K trapdoor expansion in, map it as CHIP, and then put all the FAST ram (up to 8MB) that you require on the 500XP?  I think this is the normal mapping of the 500XP.

[mechy]

i think address conflict also. like it is trying to map the ram of both into the same place.
are there any jumpers on it that can be changed to set ram up?

[spaceman88]

When you add more than 512K in the trapdoor you need to add an additional line or two from the card to Gary or the 68000, because there aren't enough address lines. Does your card have this? I had a "Baseborad" with 4MB in the trapdoor and ran into compatibility problems with certain software. I then went back to the 512k and a Supra expansion on the side bus, worked muck better. I think the internal expansions are kind of "Hackish" :-).