A500 trapdoor memory: free design - Page 20

fpmpaolo · 06 June 2018, 09:09

Quote:

Originally Posted by 8 Bit Dreams

Yes
but it will be discussed in other thread, if author decides to do it, not here

Who is the author, if I can ask?

katarakt · 10 June 2018, 00:10

Quote:

Originally Posted by PeteAU

That's keirf's systest: https://github.com/keirf/Amiga-Stuff
You can download a bootable ADF there, it's good stuff for h/w testing.

I can't find the bootable adf ...where is it

edit: ah, found it
https://drive.google.com/open?id=0B6...GhXMWRvOXVDd3M

demolition · 10 June 2018, 00:13

Quote:

Originally Posted by katarakt

I can't find the bootable adf ...where is it

Look under the first header 'SysTest Binaries'. It has a link to Google Drive.

Andreaux · 04 July 2018, 11:25

I can source myself a memory with 4 of these on. Would that work?

4 pcs NEC 4218160-60 42-pin (2 x 21) chip on a 8MB EDO module.

Datasheet says 16 M-Bit Dynamic RAM, 1 M-word by 16-bit fast page mode, byte read/write mode, 5V power supply.

Thanks.

katarakt · 04 July 2018, 19:05

Yep

watman · 05 July 2018, 12:58

Is there a way to use this trapdoor expansion along with MegAChip/similar to get to full 2mb Chip + some Slow RAM in A500 (rev 5, if that matters)

1NOM155 · 05 July 2018, 14:03

Quote:

Originally Posted by watman

Is there a way to use this trapdoor expansion along with MegAChip/similar to get to full 2mb Chip + some Slow RAM in A500 (rev 5, if that matters)

I have the same question but for a rev 6

and also other question. in your expasion design there aren't memory buffers, are they not need? like commodore did on the original design of a500 memory expasion?

esel · 08 July 2018, 14:28

dont think this is possible with this design.

You will need this:

http://eab.abime.net/showthread.php?t=93130

1NOM155 · 08 July 2018, 14:56

Quote:

Originally Posted by esel

dont think this is possible with this design.

You will need this:

http://eab.abime.net/showthread.php?t=93130

Hi esel, I saw your project, but I still have my doubt. Since your adaptor dosent have memory buffers, ist needed?

cmorley · 09 July 2018, 11:01

Quote:

Originally Posted by 1NOM155

Hi esel, I saw your project, but I still have my doubt. Since your adaptor dosent have memory buffers, ist needed?

By "memory buffers" do you mean the resistor packs on an A501?

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They are required to reduce voltage undershoot (& overshoot) at the RAM chips (worse on early Amigas rev3 & rev5). Undershoot & overshoot can affect reliability and if too great will damage the RAM (which is why they are fitted on the Commodore A501).

RiP · 09 July 2018, 15:24

When I try to test memory with MBRTest-2 v1.22, it reports "Inhibiting mounted volumes..." and doesn't do anything

1NOM155 · 09 July 2018, 18:31

Quote:

Originally Posted by cmorley

By "memory buffers" do you mean the resistor packs on an A501?

Attachment 58772

They are required to reduce voltage undershoot (& overshoot) at the RAM chips (worse on early Amigas rev3 & rev5). Undershoot & overshoot can affect reliability and if too great will damage the RAM (which is why they are fitted on the Commodore A501).

Hi Cmorley,

Sorry for my late response. I'm refering to the CAS and RAS signals, also refer as Refresh "Feature" by Commodore, using a 74F27, 74F86 and a 74LS163A or 74ACT00 and 74ACT273 by Techtravels.

You can find more information by those links http://www.amigawiki.org/dnl/schematics/A500_R6.pdf by Amigawiki.org and or https://www.techtravels.org/a500-dram-card/ by Techtravels.

I know you made some refresh in your GAL program, my doubt is they will work like Commodore design?

regards,

1NOM155

cmorley · 09 July 2018, 19:36

Quote:

Originally Posted by 1NOM155

Sorry for my late response. I'm refering to the CAS and RAS signals, also refer as Refresh "Feature" by Commodore, using a 74F27, 74F86 and a 74LS163A or 74ACT00 and 74ACT273 by Techtravels.

OK, I follow.

Yes the OCS Agnus only generates refresh on (BDR)A0-A7 and not A8, hence the extra circuitry. Not all DRAM chips require the same refresh row count but many xx256 need all 512 rows visiting hence the extra logic for A8 refresh generation on A501.

So if you have an OCS Agnus and fit RAM which require 512 rows refresh then you will have a problem. ECS Agnus generates A8 on refresh I understand.

My board uses CBR refresh (CAS before RAS) to solve the problem, so it works with OCS or ECS the same.

Chris

obitus1990 · 09 July 2018, 21:08

Pete,
Are any of the Gerbers you have linked to here the same as the ones you use to make the expansions you are selling on eBay?

1NOM155 · 11 July 2018, 01:16

Nice mate doubt solved

Quote:

Originally Posted by cmorley

OK, I follow.

Yes the OCS Agnus only generates refresh on (BDR)A0-A7 and not A8, hence the extra circuitry. Not all DRAM chips require the same refresh row count but many xx256 need all 512 rows visiting hence the extra logic for A8 refresh generation on A501.

So if you have an OCS Agnus and fit RAM which require 512 rows refresh then you will have a problem. ECS Agnus generates A8 on refresh I understand.

My board uses CBR refresh (CAS before RAS) to solve the problem, so it works with OCS or ECS the same.

Chris

Chain · 11 September 2018, 21:43

Found not much of those simm, hope it will be enough for three boards:

can anybody tell which is sutable chip and which not?

Hynix HY5118164B (im sure sobebody on eab uses that)
NEC 4218165-60
SEC KM416C1204AJ-6
SEC KM416C1200AJ-6(7)
LGS GM71C18160BJ6
TI TMS418160DZ

thanks in advance

SukkoPera · 11 September 2018, 22:55

Quote:

Originally Posted by Chain

TI TMS418160DZ

Are you sure it's 160? I have used 169 successfully.

Another chip that worked for me is Alliance AS4C1M16E5-60JC.

Making a compatibility list is a good idea!

katarakt · 12 September 2018, 21:38

Hm, if i have an A500 with damaged onboard-ram ...is it possible to use this expansion as replacement for the damaged onboard ram if i desolder all amiga onboard ram chips ?

Btw...i've finished soldering 2 ramexpansions fully loaded with ram...all is working nice. Excellent ramexpansion.

katarakt · 13 September 2018, 19:39

Quote:

Originally Posted by Chain

can anybody tell which is sutable chip and which not?

TI TMS418160DZ

I've built my two expansions exactly with these rams, working excellent

But all of those you've listed should work. If they're not working, something is wrong with soldering or one or more rams you've soldered are damaged rams. Test them in old PC if you can before picking the rams from simm! This way, i've found 2 damaged EDO 72pin simm out of, puh, around 60 tested 72pin EDO simm.

Chain · 13 September 2018, 20:46

Thanks!
As i have Blizzard card in A1200 i can test it there .)

so we have Five chips confirmed as working:

Hynix HY5118164B
TI TMS418160DZ
TI TMS418169DZ
SEC KM416C1204AJ-6
Alliance AS4C1M16E5-60JC

04 July 2018, 11:25	#384
Andreaux Registered User Join Date: Jul 2018 Location: Esztergom / Hungary Posts: 1	Would this type of RAM work? I can source myself a memory with 4 of these on. Would that work? 4 pcs NEC 4218160-60 42-pin (2 x 21) chip on a 8MB EDO module. Datasheet says 16 M-Bit Dynamic RAM, 1 M-word by 16-bit fast page mode, byte read/write mode, 5V power supply. Thanks. Last edited by Andreaux; 04 July 2018 at 11:42.

13 September 2018, 20:46	#400
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	Thanks! As i have Blizzard card in A1200 i can test it there .) so we have Five chips confirmed as working: Hynix HY5118164B TI TMS418160DZ TI TMS418169DZ SEC KM416C1204AJ-6 Alliance AS4C1M16E5-60JC Last edited by Chain; 16 September 2018 at 23:02.

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04 July 2018, 19:05	#385
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	Yep

05 July 2018, 12:58	#386
watman Registered User Join Date: Apr 2018 Location: Poland Posts: 36	Is there a way to use this trapdoor expansion along with MegAChip/similar to get to full 2mb Chip + some Slow RAM in A500 (rev 5, if that matters)

08 July 2018, 14:28	#388
esel Registered User Join Date: Jul 2012 Location: Kassel Posts: 160	dont think this is possible with this design. You will need this: http://eab.abime.net/showthread.php?t=93130

09 July 2018, 15:24	#391
RiP Q Join Date: Feb 2017 Location: CD0: Posts: 139	When I try to test memory with MBRTest-2 v1.22, it reports "Inhibiting mounted volumes..." and doesn't do anything

09 July 2018, 21:08	#394
obitus1990 Registered User Join Date: May 2016 Location: Mandeville USA Posts: 203	Pete, Are any of the Gerbers you have linked to here the same as the ones you use to make the expansions you are selling on eBay?

11 September 2018, 21:43	#396
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	Found not much of those simm, hope it will be enough for three boards: can anybody tell which is sutable chip and which not? Hynix HY5118164B (im sure sobebody on eab uses that) NEC 4218165-60 SEC KM416C1204AJ-6 SEC KM416C1200AJ-6(7) LGS GM71C18160BJ6 TI TMS418160DZ thanks in advance

12 September 2018, 21:38	#398
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	Hm, if i have an A500 with damaged onboard-ram ...is it possible to use this expansion as replacement for the damaged onboard ram if i desolder all amiga onboard ram chips ? Btw...i've finished soldering 2 ramexpansions fully loaded with ram...all is working nice. Excellent ramexpansion.

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