84 pin SDRAMS - any good for Amiga modding?

Merlin · 02 February 2008, 23:21

I have a question for the hardcore modders in here.

I have two old 8Mb 84-pin SDRAMs, taken from an old Compaq Armada 4131T 133Mhz Pentium 1 laptop, the SDRAMs are of 1996 vintage.

The chips on the SDRAMs are marked SEC, KM48V2100ALT-7, 646Y, Korea and each stick of memory has four chips. Each chip has 28 legs. Reading around suggests that these are Samsung 70ns Fast Page chips.

The Compaq assembly number is ASSY 004997-001 Rev A.

I can't help but wonder that, as these SDRAMs are of similar vintage to the old beloved Miggy, could they be used to build some kind of memory expansion?

Merlin

Jope · 04 February 2008, 07:58

You need to devise an SDRAM controller, but even then the Zorro bus becomes the limiting factor for speed.. The only gain is a lot of RAM but it isn't nearly as fast as the RAM on an accelerator board.

Merlin · 04 February 2008, 09:22

@ Jope

As my machines are A500s, A600s and A1200s, Zorro slots aren't an issue. Zetr0 and I are trying to find the pinouts for the 84-pin laptop modules, unfortunately they are elusive and we haven't found them yet, have you any ideas?

Merlin

Jope · 04 February 2008, 10:42

Ok, you threw me off by insisting the modules are SDRAM. They are 32bit FPM DRAM, not SDRAM.

SDRAM SO-DIMMs have 144 pins, actually I have some EDO SO-DIMMs in 144pin also. I remember those old Compaqs, actually some old Pentium 1 era Dells had those short modules as well.

I should have looked more closely at the device specification in your first post.. Desktop Pentiums didn't get SDRAM until around 1998, laptops didn't get SDRAM until around after the Pentium 2 arrived in a mobile package.

DoogUK · 04 February 2008, 11:03

try here http://www.interfacebus.com/memory_modules.html

Jope · 04 February 2008, 11:09

Quote:

Originally Posted by DoogUK

try here http://www.interfacebus.com/memory_modules.html

As you can see, there is no pinout for those old modules in there.

http://www.interfacebus.com/memory-m...signments.html

Merlin · 04 February 2008, 11:28

@ Jope

To be honest I had seen so many descriptions for these 84 pin modules as SIMMs, SDRAMS etc. I wasn't sure what to call them, I described them as best I could! Thanks for clearing that up for me.

It seems you are having the same problems finding pinouts as we are, were these modules so bespoke that the diagrams weren't published?

Merlin

Jope · 04 February 2008, 13:01

I think it's not a real standard at all.. De Facto at best, but not something defined by JEDEC (yes, I actually took the time to browse the JEDEC specs and there was nothing).

Basically what you have there are 72pin SIMMS that are shrunk down in size, so I don't really see how doing any designs around them would benefit the greater good.. It's rather hard to find those old non-SODIMM laptop modules anyway these days, the 144pin EDO and SDRAM modules are much more common, so if you want to do a laptop RAM to Amiga adapter, perhaps it might be a good idea to look at those?

And definitely do it with SDRAM SO-DIMMs if you want to do something, EDO SO-DIMMs are as scarce as 168pin EDO DIMMs due to the short period of time when they were available.

On the other hand, why not just make the controller to use 168pin SDRAM? It's again more common and cheaper than SO-DIMMs. :-)

Merlin · 04 February 2008, 13:10

@ Jope

It wasn't for anything special, I just happen to have these around and thought that they may be good for a homebrew A600 expansion as they are so small in size. Oh well........

Merlin

Jope · 04 February 2008, 13:16

Ah..

Well, I can say that get a 72pin SIMM of a similar capacity and check out how the RAS and CAS grouping is done in those. Then armed with the datasheet of the RAM chips in your laptop module, you can trace the data and address lines and also the RAS/CAS pins.

It'll take some time, but it's probably your only way. I'm pretty sure HP will not give you the schematics to the laptop even if you ask, neither will Dell. :-(

Zetr0 · 04 February 2008, 13:27

Quote:

Originally Posted by Jopelicious

...It'll take some time, but it's probably your only way. I'm pretty sure HP will not give you the schematics to the laptop even if you ask, neither will Dell. :-(

I have indeed met with this brick wall before on more than numerious occasions... LOL actualy trying to get anything technical from dell is like trying to take blood from a stone... or alcohol from a yorkshireman.... lol

before Compaq was brought up by HP, they were quite helpfull in the technical dept.

but HP seemed to of closed the doors of late...

Merlin · 04 February 2008, 17:54

OK, change of tack then,

I have some DRAM chips which were removed from sockets on some old Cirrus Logic video cards, could these be used to make a memory expansion board?

I just want to design and build something....

M

DoogUK · 04 February 2008, 19:06

what about the old 72 pin sodimms for older laptops? wouldnt they be more suited?

Zetr0 · 04 February 2008, 22:01

@Merlin

yes, my A500 makes use of some for extra chip ram

@DoogUK

indeed, i think if memory servers they are an identical pin configuration to the regular size 72pin simm

DoogUK · 04 February 2008, 23:09

@zetro

i happen to have one of the old 72 pin ones 8 megs in size...

i might have a 4 meg one too

Zetr0 · 05 February 2008, 10:23

@Dooguk

from memory, i know in a small draw on my componets box, I have an 8mb, 2x 16mb and a 32mb one... i haver been toying with making an a500 or a600 cpu+memory upgrade that used these

DoogUK · 05 February 2008, 11:17

sounds like a good project to me...i'd love to be able to more ram in my 600 without paying a silly price for pcmcia ram.

Unfortunately i lack the knowhow to do such projects...and my computers require months of therapy if they see me reach for the soldering iron.

02 February 2008, 23:21	#1
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	84 pin SDRAMS - any good for Amiga modding? I have a question for the hardcore modders in here. I have two old 8Mb 84-pin SDRAMs, taken from an old Compaq Armada 4131T 133Mhz Pentium 1 laptop, the SDRAMs are of 1996 vintage. The chips on the SDRAMs are marked SEC, KM48V2100ALT-7, 646Y, Korea and each stick of memory has four chips. Each chip has 28 legs. Reading around suggests that these are Samsung 70ns Fast Page chips. The Compaq assembly number is ASSY 004997-001 Rev A. I can't help but wonder that, as these SDRAMs are of similar vintage to the old beloved Miggy, could they be used to build some kind of memory expansion? Merlin

04 February 2008, 10:42	#4
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	Ok, you threw me off by insisting the modules are SDRAM. They are 32bit FPM DRAM, not SDRAM. SDRAM SO-DIMMs have 144 pins, actually I have some EDO SO-DIMMs in 144pin also. I remember those old Compaqs, actually some old Pentium 1 era Dells had those short modules as well. I should have looked more closely at the device specification in your first post.. Desktop Pentiums didn't get SDRAM until around 1998, laptops didn't get SDRAM until around after the Pentium 2 arrived in a mobile package. Last edited by Jope; 04 February 2008 at 11:08.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Normal 34-pin floppy drive on external 26-pin roctec	SilverZguru	Hardware mods	45	20 December 2020 12:05
Amiga Modding Help	Cerberus73	New to Emulation or Amiga scene	16	18 May 2008 23:09
Modding xbox psu to work with amiga	Lips2k8	support.Hardware	3	07 May 2008 16:19
VGA Adapter 23 pin -> 15 pin High Density	@UAE	support.Hardware	11	16 October 2006 13:32
Modding modern mice for Amiga	Techx	support.Hardware	9	13 August 2005 00:46

04 February 2008, 07:58	#2
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	You need to devise an SDRAM controller, but even then the Zorro bus becomes the limiting factor for speed.. The only gain is a lot of RAM but it isn't nearly as fast as the RAM on an accelerator board.

04 February 2008, 09:22	#3
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	@ Jope As my machines are A500s, A600s and A1200s, Zorro slots aren't an issue. Zetr0 and I are trying to find the pinouts for the 84-pin laptop modules, unfortunately they are elusive and we haven't found them yet, have you any ideas? Merlin

04 February 2008, 11:03	#5
DoogUK Doogster Join Date: Dec 2007 Location: Dorset Posts: 1,069	try here http://www.interfacebus.com/memory_modules.html

04 February 2008, 11:28	#7
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	@ Jope To be honest I had seen so many descriptions for these 84 pin modules as SIMMs, SDRAMS etc. I wasn't sure what to call them, I described them as best I could! Thanks for clearing that up for me. It seems you are having the same problems finding pinouts as we are, were these modules so bespoke that the diagrams weren't published? Merlin

04 February 2008, 13:01	#8
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	I think it's not a real standard at all.. De Facto at best, but not something defined by JEDEC (yes, I actually took the time to browse the JEDEC specs and there was nothing). Basically what you have there are 72pin SIMMS that are shrunk down in size, so I don't really see how doing any designs around them would benefit the greater good.. It's rather hard to find those old non-SODIMM laptop modules anyway these days, the 144pin EDO and SDRAM modules are much more common, so if you want to do a laptop RAM to Amiga adapter, perhaps it might be a good idea to look at those? And definitely do it with SDRAM SO-DIMMs if you want to do something, EDO SO-DIMMs are as scarce as 168pin EDO DIMMs due to the short period of time when they were available. On the other hand, why not just make the controller to use 168pin SDRAM? It's again more common and cheaper than SO-DIMMs. :-)

04 February 2008, 13:10	#9
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	@ Jope It wasn't for anything special, I just happen to have these around and thought that they may be good for a homebrew A600 expansion as they are so small in size. Oh well........ Merlin

04 February 2008, 13:16	#10
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	Ah.. Well, I can say that get a 72pin SIMM of a similar capacity and check out how the RAS and CAS grouping is done in those. Then armed with the datasheet of the RAM chips in your laptop module, you can trace the data and address lines and also the RAS/CAS pins. It'll take some time, but it's probably your only way. I'm pretty sure HP will not give you the schematics to the laptop even if you ask, neither will Dell. :-(

04 February 2008, 17:54	#12
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	OK, change of tack then, I have some DRAM chips which were removed from sockets on some old Cirrus Logic video cards, could these be used to make a memory expansion board? I just want to design and build something.... M

04 February 2008, 19:06	#13
DoogUK Doogster Join Date: Dec 2007 Location: Dorset Posts: 1,069	what about the old 72 pin sodimms for older laptops? wouldnt they be more suited?

04 February 2008, 22:01	#14
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Merlin yes, my A500 makes use of some for extra chip ram @DoogUK indeed, i think if memory servers they are an identical pin configuration to the regular size 72pin simm

04 February 2008, 23:09	#15
DoogUK Doogster Join Date: Dec 2007 Location: Dorset Posts: 1,069	@zetro i happen to have one of the old 72 pin ones 8 megs in size... i might have a 4 meg one too

05 February 2008, 10:23	#16
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Dooguk from memory, i know in a small draw on my componets box, I have an 8mb, 2x 16mb and a 32mb one... i haver been toying with making an a500 or a600 cpu+memory upgrade that used these

05 February 2008, 11:17	#17
DoogUK Doogster Join Date: Dec 2007 Location: Dorset Posts: 1,069	sounds like a good project to me...i'd love to be able to more ram in my 600 without paying a silly price for pcmcia ram. Unfortunately i lack the knowhow to do such projects...and my computers require months of therapy if they see me reach for the soldering iron.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)