Trapdoor A500 memory card info request

[Vipersan]

So..I recently purchased a 512k memory card (modern adaption) from Bruktmoped (fleabay) ..and was gifted a free gary adapter pcb with it.
The card was only partially populated to give an extra 512k ...but fully populated it can theoretically deliver an upgrade to 1mb chip ram ...and 1.5 mb+ slow ram ..
This would of course require a Gary adapter..and so I not only built up the Gary adapter but also fully populated the pcb to include 4 x 512 k ram chips ...and the missing RTC.
The RTC is now working fine but I'm having trouble finding the much needed info to have all the ram recognised.
From what I have found so far ..2 wires need to run between the Gary adapter and the trapdoor card ..tagged..sel 0 and sel 1.
and a trace cut to isolate the centre pin of JP2 on my Rocklobster 6A A500.
The centre connnection of JP2 is then connected to RASC.
These mods are done ..and luckilly my A500 is already fitted with the Fatter Agnus A372A.
There are various jumpers on the expansion board which I cannot find info on and I'm assuming I need to know what these do in order to correctly configure the pcb to max out the slow ram.
The board is identified as 'A500 Trapdoor memory expansion Rev B.6 2017/9/19 '

So has anyone seen this board before and can offer help or info ?
rgds
VS

[jbilander]

Looks like a revision of Pete's board. I believe you will find all information you'll need in that thread.

http://eab.abime.net/showthread.php?t=85395

[Vipersan]

Grateful thanks jbilander ..I'll go take a look.
rgds
VS

[Vipersan]

Nice ..
Thanks for the pointers buddy..
Looks like I'm making progress..see photos
rgds
VS

[Mathesar]

Originally Posted by Vipersan

Nice ..
Thanks for the pointers buddy..
Looks like I'm making progress..see photos
rgds
VS

The wires from the gary adapter to the memory board go to the wrong connector. They should go to the connector on the top right, near the '139 chip.
Also, it seems like your gary adapter has no decoupling capacitors mounted.

[Vipersan]

Many thanks Mathesar ..I'll fit some decoupling caps 100nf should do ?
..and try moving the wires tonight ..
Curious it does appear to work as it is..
cheers mate
VS

[Mathesar]

Originally Posted by Vipersan

Many thanks Mathesar ..I'll fit some decoupling caps 100nf should do ?
..and try moving the wires tonight ..
Curious it does appear to work as it is..
cheers mate
VS

Yes, 100nF will perfectly do.


The Amiga will see 1MB chip and 1,5MB fast because the Gary adapter "tricks" the Amiga. Even if you would remove the connection between the Gary adapter and the trapdoor board altogether you will get that. Whether you can really *use* that memory depends on proper configuration of the trapdoor board and the wires to the Gary adapter.

[Vipersan]

Cheers Mathesar ..
I fitted the decoupling caps ...which was tricky as the Gary base was already in place ..
Some tight soldering down those holes in the base ..lol
I moved sel0 and sel1 to the correct pins ...and Kiers software is telling me that I have 1mb chip and 1.5 mb slow as before ..
I guess I need to correctly set all jumpers both on the Gary adapter and the trapdoor pcb now ..so I will grab some more photos which hopefully you can take a look at for me and point out if anything is still wrongly set..
I'll upload the photos in the next 30 minutes..
rgds
VS

[Vipersan]

Hopefully I'll get this properly configured with Mathesars help..
which is very much appreciated.

[Mathesar]

Originally Posted by Vipersan

Hopefully I'll get this properly configured with Mathesars help..
which is very much appreciated.

You're welcome
Your jumper settings look all correct to me.
However, there is two things you need to check.

Firstly, the 4 jumper block in the middle of the trapdoor board has no jumpers which is correct. However, on the PCB there are traces between the pads of the jumpers that need to be cut in order for the gary adapter to work correctly like this:

If the traces are indeed cut then you are good to go.

Secondly, the jumper on the gary adapter needs to be set to "more". Normally there is a trace on the board that takes care of this so that no jumper is needed. I think the trace is still there otherwise you wouldn't see all the RAM. However, it wouldn't hurt to check.

In any case, the proof is in the pudding Just load up some programs or copy some data to RAM: to use up all the memory. If everything stays stable, it works!

[Vipersan]

Many thanks Mathesar..
Yes indeed I have cut all the track links in your photo ..
I just fitted headers in case I needed to add links in the future
I will check for the link on the Gary adapter ..but as you say it is working so probably ok.
Quick qustions ..
What is the EXram link for ..currently I have it closed..
and the Clock link appears to not be needed ? ..the RTC is working with or without it ?
and again ..your help has been most useful.
cheers
VS

..btw This morning I received a super Denise chip ..which I had ordered a while back when I retrofitted chip bases to the blank ram spaces of the A500 6A pcb ..
Since I already had the later Agnus (8372A) fitted I figured an extra 512k chip ram was easily doable onboard.
JP2 and JP7 needed attention but it did work..
but with the trapdoor card fitted ..now redundant I guess.
I cant have both sadly ..lol
But regarding the super Denise..
Is this pin comparible with my 6A ...and would I get any benefit from fitting it ?

[Mathesar]

Originally Posted by Vipersan

..btw This morning I received a super Denise chip ..which I had ordered a while back when I retrofitted chip bases to the blank ram spaces of the A500 6A pcb ..
Since I already had the later Agnus (8372A) fitted I figured an extra 512k chip ram was easily doable onboard.
JP2 and JP7 needed attention but it did work..
but with the trapdoor card fitted ..now redundant I guess.
I cant have both sadly ..lol
But regarding the super Denise..
Is this pin comparible with my 6A ...and would I get any benefit from fitting it ?

Dunno about pin Compatibility. AFAIK a super Denise will give you some extra screenmodes like superhires and productivity modes.

[Jope]

It is a drop in replacement.