Maximum amount of supported RAM in OS 3.1?

emuola · 01 October 2009, 21:17

Forgive me my stupidity, but I couldn't find this piece of info from wikis or anywhere else (or I just didn't know the right terms). What is the maximum amount of RAM OS 3.1 supports?

tero · 01 October 2009, 21:26

In the WinUAE.chm (Background Information) is this about RAM:

Depending on the processor variant, you can expand the RAM up to 10 MB or theoretically up to 2 GB. The limit of 2 GB is valid for the Amiga models A3000 and A4000. On the mainboard of these computers you can plug in up to 18 MB RAM, and for every of the four Zorro-III bus expansion you can expand the memory to the maximum!

But no words about the used WB's version

seuden · 01 October 2009, 21:27

I thought it depended on the processor or something?

EDIT: Beaten by a better post!!!

emuola · 01 October 2009, 21:36

Ok, I was thinking about my A1200. Any experiences with the maximum amount of RAM in OS 3.1?

DDNI · 01 October 2009, 21:37

256MB is the most that any A1200 accelerator can access (BPPC) Ergo 256MB is the maximum RAM accessible to OS3.1

thomas · 01 October 2009, 21:44

There is no limit in software. All OS versions from 1.0 to 3.9 support all RAM which can exist in hardware. The address space of a 32bit processor is 4GB, so this is the natural limit.

In reality, in the original A1200 case you can have 256 MB as can be put on the BPPC. In a tower case with a Zorro3 busboard you can expand memory the same way as on an A3000/A4000.

Toni Wilen · 01 October 2009, 21:44

Only OS limit (all versions, including KS 1.x) is high address bit which can't be one because some exec memory routines (mis)use it as a flag = slightly under 2G max.

Existing hardware rarely supports more than 256M or so.

EDIT: nice posting timing..

emuola · 01 October 2009, 21:45

Ok, thanks

That 256 MB sure is plenty

DDNI · 01 October 2009, 21:45

I suppose if we are being pedantic, the max RAm in a classic A1200 is closer to 258MB (2MB Chip 256 Fast)

DoogUK · 01 October 2009, 21:56

262mb if you add 4mb sram by pcmcia

alexh · 01 October 2009, 23:29

Someone over at Amiga.org had trouble going over 384Mbytes FastRAM.

128MByte on the CSPPC
128MByte on DKB3128 (1)
128MByte on DKB3128 (2)
128MByte on DKB3128 (3)

No matter what he did he was unable to get the third card to work correctly.

DDNI · 01 October 2009, 23:29

bah! yet again I am beaten by a more pedantic Amigan

DoogUK · 02 October 2009, 03:22

Quote:

Originally Posted by DDNI

bah! yet again I am beaten by a more pedantic Amigan

Shadowfire · 02 October 2009, 04:38

Yeah, I saw that thread about the DKB boards, and it's probably a bug in the Z3 autoconfig code. Y'know, they probably didn't test it with a gigabyte of RAM, since at the time they made the machines it would have been ungodly expen$ive to add that much memory to a machine.

But as for the OS itself, as Toni said, up to 2GB of RAM since the executive is "bad" and uses bit #31 as a flag for some routines, notably to mark the last entry in a table of addresses.

Photon · 02 October 2009, 05:24

Quote:

Originally Posted by DDNI

256MB is the most that any A1200 accelerator can access (BPPC) Ergo 256MB is the maximum RAM accessible to OS3.1

Yeah, this is what I've concluded too after a brief search. Maybe there's a hardware hero out there that has managed more!?

Toni Wilen · 02 October 2009, 08:16

Quote:

Originally Posted by alexh

Someone over at Amiga.org had trouble going over 384Mbytes FastRAM.

128MByte on the CSPPC
128MByte on DKB3128 (1)
128MByte on DKB3128 (2)
128MByte on DKB3128 (3)

No matter what he did he was unable to get the third card to work correctly.

Probably bug in handling of multiple expansions or merging of multiple cards' address spaces because single 1.5G Z3 expansion works in UAE.

rkauer · 02 October 2009, 08:25

IIRC, the bug itself is in the expansion.library.

01 October 2009, 21:17	#1
emuola Registered Whdload user Join Date: Oct 2006 Location: Finland Age: 48 Posts: 532	Maximum amount of supported RAM in OS 3.1? Forgive me my stupidity, but I couldn't find this piece of info from wikis or anywhere else (or I just didn't know the right terms). What is the maximum amount of RAM OS 3.1 supports?

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01 October 2009, 21:26	#2
tero Registered User Join Date: Jan 2009 Location: M'Gladbach Age: 46 Posts: 621	In the WinUAE.chm (Background Information) is this about RAM: Depending on the processor variant, you can expand the RAM up to 10 MB or theoretically up to 2 GB. The limit of 2 GB is valid for the Amiga models A3000 and A4000. On the mainboard of these computers you can plug in up to 18 MB RAM, and for every of the four Zorro-III bus expansion you can expand the memory to the maximum! But no words about the used WB's version

01 October 2009, 21:27	#3
seuden uber cool demi god Join Date: Jun 2006 Location: Kent/England Posts: 2,073	I thought it depended on the processor or something? EDIT: Beaten by a better post!!!

01 October 2009, 21:36	#4
emuola Registered Whdload user Join Date: Oct 2006 Location: Finland Age: 48 Posts: 532	Ok, I was thinking about my A1200. Any experiences with the maximum amount of RAM in OS 3.1?

01 October 2009, 21:37	#5
DDNI Targ Explorer Join Date: Mar 2006 Location: Northern Ireland Posts: 5,433	256MB is the most that any A1200 accelerator can access (BPPC) Ergo 256MB is the maximum RAM accessible to OS3.1

01 October 2009, 21:44	#6
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 7,032	There is no limit in software. All OS versions from 1.0 to 3.9 support all RAM which can exist in hardware. The address space of a 32bit processor is 4GB, so this is the natural limit. In reality, in the original A1200 case you can have 256 MB as can be put on the BPPC. In a tower case with a Zorro3 busboard you can expand memory the same way as on an A3000/A4000.

01 October 2009, 21:44	#7
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,574	Only OS limit (all versions, including KS 1.x) is high address bit which can't be one because some exec memory routines (mis)use it as a flag = slightly under 2G max. Existing hardware rarely supports more than 256M or so. EDIT: nice posting timing..

01 October 2009, 21:45	#8
emuola Registered Whdload user Join Date: Oct 2006 Location: Finland Age: 48 Posts: 532	Ok, thanks That 256 MB sure is plenty

01 October 2009, 21:56	#10
DoogUK Doogster Join Date: Dec 2007 Location: Dorset Posts: 1,069	262mb if you add 4mb sram by pcmcia

01 October 2009, 23:29	#11
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,473	Someone over at Amiga.org had trouble going over 384Mbytes FastRAM. 128MByte on the CSPPC 128MByte on DKB3128 (1) 128MByte on DKB3128 (2) 128MByte on DKB3128 (3) No matter what he did he was unable to get the third card to work correctly.

02 October 2009, 04:38	#14
Shadowfire Registered User Join Date: Aug 2001 Location: Connecticut USA Posts: 617	Yeah, I saw that thread about the DKB boards, and it's probably a bug in the Z3 autoconfig code. Y'know, they probably didn't test it with a gigabyte of RAM, since at the time they made the machines it would have been ungodly expen$ive to add that much memory to a machine. But as for the OS itself, as Toni said, up to 2GB of RAM since the executive is "bad" and uses bit #31 as a flag for some routines, notably to mark the last entry in a table of addresses.

02 October 2009, 08:25	#17
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	IIRC, the bug itself is in the expansion.library.

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