A4000 112MB Memory hack

[Crumb]

Hi

Here's Meutoxo's improved version of Meutoxo's memory hack :-)

You can:
a) use 1x 64MB simm and use 64MB with fastramsey (requires the 64MB jed)
b) use 2x 64MB simm and use 112MB without fastramsey
c) Use a 128MB simm to use 112MB

All 64/112MB of memory are autoconfig.

I've done the hack successfully in two different A4000D (desktop and micronik) and also in my A4000T (let me know if it works for you as we only tested it on my own A4kT) so I will provide support here, don't bug Meutoxo as he's very busy.

I have not attached the doc file and just the PDF as it made the archive too big.

If you do any change to the pcb or jed files please share here.

BTW, I've noticed that the new A4000+ motherboard seems to lack the empty GAL area, in that case you will need the PCB on top of ramsey just like A4000T owners.

Enjoy

[alexh]

http://www.amibay.com/showthread.php...our-A4000-mobo

http://www.amibay.com/showthread.php...B-Fast-Ram-mod

http://leblogdecosmos.blogspot.co.uk...d-64-mo-i.html

[Peckmore]

Originally Posted by alexh

http://www.amibay.com/showthread.php...our-A4000-mobo

http://www.amibay.com/showthread.php...B-Fast-Ram-mod

http://leblogdecosmos.blogspot.co.uk...d-64-mo-i.html

Apologies if I've missed something but none of the linked pages mention the 112MB memory hack, only 64MB? Is this the first time we've seen a 112MB hack for the A4000?

[trixster]

Very interesting. How much work is required to 'upgrade' a machine that's already had the 64mb mod done to the new 112mb limit?

[SpeedGeek]

Sounds like an interesting hack, but I hope Meutoxo does not map the extra RAM into the same address space as 4MB Romy:

http://eab.abime.net/showthread.php?t=88182

$1000000-$13FFFFF

[hooverphonique]

Originally Posted by SpeedGeek

Sounds like an interesting hack, but I hope Meutoxo does not map the extra RAM into the same address space as 4MB Romy:

http://eab.abime.net/showthread.php?...highlight=romy

$1000000-$13FFFFF

He does, it's all mapped linearly down from 07FFFFFF, so the question is if it will mess with the Romy since 01000000 - 013FFFFF is now handled by Ramsey whether you are using 112MB or not... The weird thing is that the OS detects 01000000-03FFFFFF as memory even though it's supposed to be reserved space (I guess this might affect the Romy also, if you have fast ram all the way down to the Romy address space, even if it doesn't overlap the ram).

[Crumb]

Originally Posted by SpeedGeek

Sounds like an interesting hack, but I hope Meutoxo does not map the extra RAM into the same address space as 4MB Romy:

http://eab.abime.net/showthread.php?...highlight=romy

$1000000-$13FFFFF

Hi, original unmodified exec scans 01000000-07ffffff (IIRC) and autoconfigures the memory found in that area as FASTRAM. No software patches required, no manual memory adding. Caches are set up accordingly. Exec has worked that way for decades. Bacterio's 64MB hack also took advantage of that. Meutoxo's 64&112MB hacks too.

Would it be possible to locate ROMY's extra ROM >1MB elsewhere?

[SpeedGeek]

Originally Posted by Crumb

Hi, original unmodified exec scans 01000000-07ffffff (IIRC) and autoconfigures the memory found in that area as FASTRAM. No software patches required, no manual memory adding. Caches are set up accordingly. Exec has worked that way for decades. Bacterio's 64MB hack also took advantage of that. Meutoxo's 64&112MB hacks too.

Would it be possible to locate ROMY's extra ROM >1MB elsewhere?

Here is some info from the A3000+ manual:

A3000 and earlier systems. Chip RAM, for example, is mapped as in earlier
systems at $00000000-$001FFFFF. Since the original Amiga architecture
supported only 2MB of Chip RAM, though, any additional Chip memory will
have to be mapped non-contiguously. The A3000+ solution to this is to
map the memory at $00000000 to the base of a new region, starting
at $01000000. The A3000+ architecture physically supports 8MB of Chip
RAM, so should an 8MB Alice be designed, the additional 6MB winds up in
the $01200000-$017FFFFF range. The next 8MB has been reserved for use
as Chip RAM in future systems.

Similarly, the A3000 used up all the reserved ROM space in the original
Amiga memory map,the range from $00F80000-$00FFFFFF, for the 512K
space used by AmigaOS 2.0. To support at least 1MB of ROM on machines
with 24 bit addressing, the previously unused 512K from
$00E00000-$00EFFFFF. To support additional ROM in an upward compatible
fashion, the A3000+ addresses 4MB of ROM at $03C00000-$03FFFFFF. The
512K chunk at $00F80000 is also mapped at $03F80000 and the 512K
chunk at $00E00000 is also mapped at $003E0000.

The original Rev. 9 Romy mapped the 4MB of ROM at $3C00000-$3FFFFFF but was moved in Rev. 10-11 to space reserved for Chip memory expansion. There is no mention of Fast memory expansion via Ramsey but even if was left open for future expansion, it would not have gone beyond 64MB due to the address space reservations made above.

[Chucky]

Well I cannot even see use for more than 1MB of rom. so.. 112MB is no issue for me

[Crumb]

Originally Posted by SpeedGeek

The original Rev. 9 Romy mapped the 4MB of ROM at $3C00000-$3FFFFFF but was moved in Rev. 10-11 to space reserved for Chip memory expansion. There is no mention of Fast memory expansion via Ramsey but even if was left open for future expansion, it would not have gone beyond 64MB due to the address space reservations made above.

Whatever was written or planned in the vapourware Amigas manual doesn't matter much because original Exec in the ROMs of all A4000 variants sold worldwide configures all that range as fastram memory. From a software viewpoint it's clear that the 4MB rom was not planned as exec mounts that area as RAM. Arguing about this is useless so Meutoxo has told me that he may create soon a rommy-friendly version of the GAL with just 96MB support so everybody is happy. Please be patient my friend ;-)

[kolla]

Looks like new A4000 motherboards will need some jumpers, hehe.

[SpeedGeek]

Originally Posted by Crumb

Whatever was written or planned in the vapourware Amigas manual doesn't matter much because original Exec in the ROMs of all A4000 variants sold worldwide configures all that range as fastram memory. From a software viewpoint it's clear that the 4MB rom was not planned as exec mounts that area as RAM. Arguing about this is useless so Meutoxo has told me that he may create soon a rommy-friendly version of the GAL with just 96MB support so everybody is happy. Please be patient my friend ;-)

Well, some of the "Vapourware" was actually planned for the A4000. I suppose you have never heard about the "Free Sex and Beer Jumper" comment by Dave Haynie.

Also, exec does configure any Fast RAM but only Chip RAM! Both the A3000 and A4000 motherboard Fast RAM is configured by the "Bonus" code. The bonus code just checks for Fast RAM below $8000000 and keeps adding it until no more RAM is found.

EDIT: If Meutoxo want's to use the space originally reserved for Chip RAM expansion for his hack he has just as much right to use it as I do. I just thought he should be warned about the 4MB Romy version in advance.

[Jope]

Originally Posted by kolla

Looks like new A4000 motherboards will need some jumpers, hehe.

Well, just like many Amiga models have some model specific hard coded stuff in the KS ROM, there is no reason to not patch the ROM to be specific for any models made by the community. :-)

[Tomislav]

From A4000 Service Addendum - part of A4000 memory map:

16+88+8=112MB - that means romy can't be there or you must use only 108MB (112-4) somehow.
A4000 maps motherboard Fast RAM backwards from 07FFFFFF. That mean if you put 1MB of that memory it is from 07F00000 to 07FFFFFF. 2MB goes 07E00000 - 07FFFFFF. ...

[SpeedGeek]

AFAIK Meutoxo has already released the 96MB Fast RAM version. But of course, the 1MB Romy version solves the problem too.

BTW, I've already had 2 requests for an 8MB Romy!

(No good deed goes unpunished).

[thebajaguy]

At that rate, let's go back to an A1000-like WCS option with a boot strap ROM (if you don't want the stock-like releases)? That would make it easier to load the (experimental/final) ROM image from the HD instead of floppy, and we don't have to worry about calling for FastROM as it's already in 32-bit RAM.

[discigabi]

Q01:
Is there any downside of doing this mod? Compatibility issues with software/hardware? or any other known issues?

Q10:
The PDF says (page 2):
-"For 112MB config you should use 2x 64MB simms connected to U852 and U853..."
Currently I have the 64MB mod with 2x32MB(double sided) in every second fastram socket U852&U850 (only these two fastram sockets are soldered onto the board in order to be able to use double sided rams properly).
Is it possible somehow to use U852&U850 for this 112MB mod with 2x64MB(double sided) instead of U852&U853?

Q11:
-Still page 2: "... or a single 128MB simm connected to U853 (the 2nd fastram simm)"
Isnt U853 the 1st fastram simm on rev B?
Or it was meant to be: "...U852(the 2nd fastram simm)"?

[hooverphonique]

Originally Posted by discigabi

Q01:
Q10:
The PDF says (page 2):
-"For 112MB config you should use 2x 64MB simms connected to U852 and U853..."
Currently I have the 64MB mod with 2x32MB(double sided) in every second fastram socket U852&U850 (only these two fastram sockets are soldered onto the board in order to be able to use double sided rams properly).
Is it possible somehow to use U852&U850 for this 112MB mod with 2x64MB(double sided) instead of U852&U853?

No. You need to use 2x64MB in the first two slots, or 1x128MB in the second slot.

[discigabi]

Thanks a lot hooverphonique.

[discigabi]

If anyone is interested I have pulled together a brief "guide" of a non-destructive implementation:
http://bit.ly/A4000_112MB_upgrade_supplmtry