8 Mb CHIP RAM on All Amigas

[Hyperspeed]

A lot of things like scandoublers/ff and '030 accelerators for the A600 feature a chip that sits on top of another chip and bypasses the original.

I wish people would stop saying "can't be done". With enough resources and ideas I'm sure something could be worked out.

Trouble is, with BVision and PIV cards the urge to develop a hardware based solution to the 2MB limit is not strong enough.

I heard once there was an '040 sidecar for the A500 and the Bodega Bay tower for A500 allowed A2000 GFX cards right?

I can see that more ChipMem would be handy for classic apps, especially killer apps you'd like to 'nourish' with all the tricks you can use!

FBlit conflicts with things though and is a severe hack, I don't think Shapeshifter likes it.

Shame the AGA plans were lost, it could have made for great fun over the last decade. Didn't Mick Tinker have the plans for BoXeR? What happened to his work...

The fake GPU idea is a good one, tricking the Amiga into using GFX card memory as ChipMem - maybe with some sort of FBlit/Hardware combo. The board could have lightning fast DDR memory.

[Tricky]

@Zac67
The program will have to patch the OS memory allocation functions.  Although each "page" will have its own set of programs running, you won't be able to mix programs from one page with programs from another.  So if you drag the screen down, you'd get nothing!  (Or another program that was running on the same page.)  There would be some other method of doing it, maybe a key combination.

Chip registers won't be written to by the copper lists of programs that are in a background page, because their copper lists will not be active.  Besides, programming the blitter from there is not a very OS friendly thing to do... OS friendly blits, however, could be taken over by FBlit, and the fast-ram mirror of the blitter busy bit could be held at 1 to ensure any programs that do try to access it the naughty way have to wait until you look at them again.

The MMU would just divert writes to hardware registers elsewhere so they don't actually do anything, it doesn't try to simulate their behaviour in any way.  (At least not the "write" registers anyway, the readable ones could be updated periodically.)  Although when a page is switched back, the values there could be loaded into the real registers.

Why do I want to do this?  I don't really... just sounded like an interesting problem to solve!

[jdiffend]

First of all, the OS doesn't care how much chip RAM you have.  Memory is just tagged as different types and it allocates whatever type you want from the memory list.

It's the hardware that cares.  The custom chips only have access to one buss of the dual buss architecture... chip RAM.  
Without a redesign of the custom chipset you won't be able to have more.  Minimig wouldn't have such a limitation.

[Piru]

The fake GPU idea is a good one, tricking the Amiga into using GFX card memory as ChipMem - maybe with some sort of FBlit/Hardware combo. The board could have lightning fast DDR memory.

It's a very bad idea, reading graphics card memory is even slower than chip memory.

Ok I don't mind people having their dreams, but when the ideas conflict with reality I feel obliged to comment.

[Hyperspeed]

by Piru:
It's a very bad idea, reading graphics card memory is even slower than chip memory.

Ok I don't mind people having their dreams, but when the ideas conflict with reality I feel obliged to comment.

Ok, it's been said that the A4000's ChipMem resides on a removeable 72-pin SIMM right?

So what if a larger SIMM was used, possibly of a higher nanosecond rating then a piggy-back chip placed over Agnus?

:idea:

If you can add a 10 MIPS 32-Bit '030 to a 16-Bit 68000 A600 then I'm sure that at the very least the old 2MB/8MB jumper on the A4000 could be hacked.

Surely GFX card memory is only slower than the crap 80ns ChipMem memory because it has to go through the Zorro bus, what if it could bypass this with a piggyback board?

:inquisitive:

I think the Power Flyer and internal scandoublers work in a similar way. There are ROM switchers so why can't a MiniMig style Agnus switcher be thought through?

Just for laughs of course, to prove we can!


:laughing:

[Piru]

Ok, it's been said that the A4000's ChipMem resides on a removeable 72-pin SIMM right?

So what if a larger SIMM was used, possibly of a higher nanosecond rating then a piggy-back chip placed over Agnus?

The system would still only see 2MB of chip memory. The memory speed would not be faster.

For any benefits all custom chips would need to be adjusted, not just agnus. Also, it is likely that various address lines are not even physically connected, considering the maximum memory is 2MB. Basically you'd end up replacing the whole motherboard and chipset anyway.

Surely GFX card memory is only slower than the crap 80ns ChipMem memory because it has to go through the Zorro bus

Actually this is generic. Graphics card memory access speed is highly asymmetric (writing is fast, reading is very slow). This is the same for modern gfxcards aswell.

[leirbag28]

Piru wrote:
@leirbag28

Before continuing with this debate, would you be kind enough to explain what would one use the 8MB chip memory for? What benefits does 8MB chip memory offer?
----------------------------------------------------------------------


Capital punishment
Super StreetFighter 2 Turbo
Hired Guns
NAPALM
T-ZERO
SCALA MM300
ELan Performer
ViewTeck
Workbench and All Multitaking applications
Digital Sound Studio (Tracker requires all samples in Chipmem)
Video Toaster (can sure use more chipMEM)


And so many Applications...........I love running 10 apps at once if possible....and still be able to execute SLAMTILT or Capital punishment without having to reboot.

WinUAE is a perfect example. I can open so many Apps on it.......one can prove how excellent Amigas are at multitasking if we had more ChipRAM.


Someone here said even with a Gfx card the limit is only 2mb Chip.................hmmmm Im pretty sure I have read you can have 4mb with a CyberVision64 or Picasso and having a Gfx card benefits the Video Toaster as it uses the extra chipMEM from the Card to run.


And Yes!  where there is a will, there is a Way.....PiggyBacking Chips on one another  just might work!

I have heard "It cant be done" in the Amiga community so many times...and they were all wrong.

One has to think of things that have not yet been created.

For example Compact Flash cards and Memory Sticks and SD cards and such were said to be not possible to use on the Amiga. but we can use them now....all that was required was drivers. Same with USB.......now we have USB.............USB couldnt be done on the A600.....I have a Clockport in my A600 now ready for USB

ECS Amigas were said to display a Max of 16 colors in hires Interlaced........yet Broadcast Titler 2.0 displays 320 at once using a trick..........different screens on one screen. Awesome!   this same concept has been applied to games and can be applied even more if we had more ChipMEM

I have ran out of ChipMEM trying to display a large JPEG.


Never forget!  Amiga Makes It Possible!

and Why?  cuz we have a strong community that loves this machine.

[DamageX]

hmmmm Im pretty sure I have read you can have 4mb with a CyberVision64 or Picasso

Nope, this is absolutely not the case. 2MB is the limit. Seriously.

PiggyBacking Chips on one another just might work

Not a bad idea, but still the answer is no. The trouble is that Agnus/Alice has many different DMA channels and stores different addresses for each one. When Agnus/Alice accesses chipmem, there is no way for any other piece of hardware to know which DMA channel is being served, so there is no way for any other piece of hardware to provide relevant additional address bits.

[leirbag28]

Not a bad idea, but still the answer is no. The trouble is that Agnus/Alice has many different DMA channels and stores different addresses for each one. When Agnus/Alice accesses chipmem, there is no way for any other piece of hardware to know which DMA channel is being served, so there is no way for any other piece of hardware to provide relevant additional address bits.
-------------------------------------------------------------------------

@DamageX

That kind of makes sence and I probably can see that being the case. But maybe there is a way through software telling the Systems and OS that the rest of the ChipRAM is somewhere else and is Virtual Memory..........redirection.....................invisible to all Applications and games.

[Piru]

@leirbag28

Someone here said even with a Gfx card the limit is only 2mb Chip. hmmmm Im pretty sure I have read you can have 4mb with a CyberVision64 or Picasso and having a Gfx card benefits the Video Toaster as it uses the extra chipMEM from the Card to run.

No.

For example Compact Flash cards and Memory Sticks and SD cards and such were said to be not possible

Can't remember anyone saying these would be impossible. It was just lack of drivers, obviously possible.

Same with USB

Was always possible if someone just created the HW. Someone did. The only way to get more than 2MB chip memory is by full hw emulation or total recreation of all hardware (minimig could have more than 2MB, but it won't. It will be A500 compatibility device).

ECS Amigas were said to display a Max of 16 colors in hires Interlaced, yet Broadcast Titler 2.0 displays 320 at once using a trick

Obviously possible since you can change palette registers with copper. This never was impossible.

But:

this same concept has been applied to games and can be applied even more if we had more ChipMEM

No, it can't.

I have ran out of ChipMEM trying to display a large JPEG.

Use a program that reduces the picture size to fit the screen.

But maybe there is a way through software telling the Systems and OS that the rest of the ChipRAM is somewhere else and is Virtual Memory redirection invisible to all Applications and games.

No, there is not.

Really there isn't.

[Zac67]

Sigh...

Look, any chipmem access by the chipset works like this:
- Agnus generates the address to the chip bus (for the 'DMA')
- the data gets transferred to the chip that needs it

All address registers for the custom chips reside within Agnus (hence its name from Address Generator). The registers are 21 bits wide and the address bus is 21 bits wide (not precisely since we address words/longwords, but that doesn't make a difference).
There's absolutely no way to make Agnus see more than 2 Megs - apart from redesigning it of course. A redesign would need
- additional address lines to CPU bus switch
- additional address or select lines for RAM control
- enlarged address registers
- additional or larger RAM chips

The whole idea about virtualising chipmem and swapping it when needed won't work, it leads to the exact same problems there are with resource tracking within AmigaOS - there's simply no way.
And: Before you engineer a special MMU for the chipset, it'd be much simpler and more efficient to redesign Agnus (wouldn't need a major OS rewrite). So, go ahead and ask Dennis to share his Minimig work with you to build a (nearly) drop in replacement for Agnus.

[Doobrey]

leirbag28 wrote:

Someone here said even with a Gfx card the limit is only 2mb Chip.................hmmmm Im pretty sure I have read you can have 4mb with a CyberVision64 or Picasso and having a Gfx card benefits the Video Toaster as it uses the extra chipMEM from the Card to run.

Gfx card memory is not chip memory, it can't be accessed by the custom chips.

[countzero]

Zac67 wrote:
Sigh...

Look, any chipmem access by the chipset works like this:
- Agnus generates the address to the chip bus (for the 'DMA')
- the data gets transferred to the chip that needs it

All address registers for the custom chips reside within Agnus (hence its name from Address Generator). The registers are 21 bits wide and the address bus is 21 bits wide (not precisely since we address words/longwords, but that doesn't make a difference).
There's absolutely no way to make Agnus see more than 2 Megs - apart from redesigning it of course. A redesign would need
- additional address lines to CPU bus switch
- additional address or select lines for RAM control
- enlarged address registers
- additional or larger RAM chips

something tells me that you can't get away with only redesigning agnus. The custom chips themselves, when requesting data use 21 bit addresses ? so they should be upgraded as well for the extra address line ?

[Tricky]

@Zac67

It is possible to track memory resources on the Amiga.  You could patch the memory management functions in exec.library.  Normally AmigaDOS doesn't keep track of any memory reserved, it only keeps track of what's left.  But you could insert a patch that before reserving the memory, gets the current process handle, and stores that somewhere in a table along with the address and amount of memory reserved.

I was considering writing such a patch, not to expand chip RAM, but just so that you can free up any memory reserved by programs that they forgot to free up when they exited.

However, if you can do this, then when the chip memory gets full, we can look at this table and see what programs we can "swap out".  You'd have to put the entire process to sleep (including taking its screen out of the screen list), as it would have no way to access any chip memory it reserved while it was swapped out.  So you wouldn't have full multitasking anymore, but you could get back to the old program when the new one frees up its chip memory.

Realtime switching with full multitasking obviously isn't an option as a program's chip memory can still be accessed by the hardware even when it isn't the current process, and furthermore, it takes far too long to copy memory around like that (it would have to be physically copied into and out if chip/fast ram on every process switch).

But maybe there is a compromise option, that allows you to effectively use more than 2Mb of chip ram, but only a maximum of 2Mb at any one time.  We could do it manually with some sort of "task manager" like Windows has.  You see a window with a list of all the current programs and how much chip ram they are using, and can put individual processes to sleep in fast ram when you want to, and bring them back later.

[motorollin]

To summarise for those who can't take the hint :-)

1. The custom chips are physically only able to see a maximum of 2MB of chip RAM.

2. The only way to change 1. is to replace the custom chips and make extensive changes to the motherboard. Since nobody has the plans for the custom chips, I don't think replacements will ever be available.

3. Since the allocation of memory isn't handled by an MMU, you cannot swap memory out.

4. Even if it was possible to use software to swap memory out, this would require the OS to be running. As soon as you run software which turns off the OS (read: a game), you lose your swapping ability, and you're back to 2MB of chip RAM.

5. This idea of emulating the chip RAM is silly. How would your software know it is supposed to use the emulator when it wants to use some chip RAM? It wouldn't, so it would just address the chip directly and totally ignore your emulator.


I understand this dream, as it would be great to lose the distinction between chip and fast mem, and pool all available RAM for use by any software or hardware. But sadly, it's just not possible. If you really, absolutely must have more than 2MB of chip RAM, use UAE.

--
moto

[Kronos]

There are only exactly 2 ways of getting more than 2MB chip:

a) emulate it, problem is, even a A4000-CSPPC+Voodoo3 running MorphOS or an OS4-beta will hardly reach A500-speeds(as you would need to run a full version of UAE).

b) create your own uber-Agnus/Alice out of a programable chip, remove the onboard Agnus/Alice, place a piggyback-PCB with the  new chip and 6 extra MB into the free space. This might work, this might also end in the need of recreating Denise,Gary and Paula too.

None of them makes really sense.

But since I'm in the mood:

c) use a PC + UAE and somehow hack a PCI_2_Zorro-adaptor and a VGA_2_VideoSlot-adaptor. Now that sounds like a fun project, and should even be able to the toaster. But then just buying a the PC-Toaster might be easier.