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Old 27 December 2019, 14:06   #1
psoma
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A500 with Baseboard 4MB loading everything to Chip Mem

Hey all,

Got myself an A500 with a Baseboard 4MB expansion last weekend, and I've managed to successfully configure it to run 1MB Chip, 3.5MB Fast Mem. Unfortunately, I have an issue where it seems to load all the drivers into Chip rather than Fast Mem (confirmed by Sysinfo), so after booting to Workbench, I'm left with only about 810k Chip Mem.

Now, the Baseboard is not autoconfigure, so an app runs in startup-sequence to add the additional RAM as Fast RAM... but any thoughts as to how I can get things to run in that Fast RAM (as it does on my 600 with a Furia accelerator)?

Cheers,

Tom
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Old 27 December 2019, 14:12   #2
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Which drivers do you mean? Which os version? How many left out icons? How many colours in your workbench?
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Old 27 December 2019, 14:51   #3
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Good questions...

WB 1.3
KS 2.05
4 colours
No icons (floppy boot)

Drivers are those loading standard with the 1.3 WB boot
Floppy and shown in the upper left box in SysInfo.
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Old 27 December 2019, 15:02   #4
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So no hard drives? Only a vanilla 1.3 floppy disk where you added the baseboard software?
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Old 27 December 2019, 21:31   #5
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This is an unfortunate limitation of any card that does not include autoconfig RAM. Every single bit of the OS before it hits the startup sequence is going to be loaded into chip memory. The best you can do without cheating is to make sure the addmemory command is the very first thing in your startup-sequence, preferably before Setpatch if you can avoid it crashing.

Next best thing you can do is cheat and add a custom vector on reboot that adds in the RAM right after the kernel is loaded This program will do it for AmigaOS 1.3, I don't know about 2.x/3.x compatibility. Still, it should fix most of the issues you have with your current setup -- just replace the existing addmem utility you use in your startup sequence with this one, and you should see the benefits after you reboot the next time after it runs:

http://aminet.net/package/util/misc/ROMTagMem
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Old 27 December 2019, 21:41   #6
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I wonder if the baseboard tool does more than just adds the memory to the system lists. This is a 4MB trapdoor board, and apparently there is no connection to the 68000 socket. I wonder what its trick is.
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Old 27 December 2019, 21:54   #7
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Thanks @AmigaHope! Will give that a try.

@Jope: yeah, just a 1.3 boot Floppy with the Baseboard software at this stage. Getting an ide68k shortly.

And it does just look to be mapping the RAM in 512k chunks. Nothing particularly special going on, and certainly no CPU interfacing. I’m bummed as I have a VXL*30 accelerator in the machine too but it doesn’t have the RAM32 expansion in it that would give it 32 bit FastMem so I need to rely on the Baseboard

Cheers,

Tom
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Old 28 December 2019, 02:01   #8
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Quote:
Originally Posted by Jope View Post
I wonder if the baseboard tool does more than just adds the memory to the system lists. This is a 4MB trapdoor board, and apparently there is no connection to the 68000 socket. I wonder what its trick is.
The trick is the Gary board, which gives it access to the appropriate bus lines. The chip bus is perfectly capable of responding to accesses across all 24-bits of address space, it just normally doesn't. Getting under Gary lets trapdoor devices control this.

Last edited by AmigaHope; 28 December 2019 at 02:47.
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Old 28 December 2019, 02:03   #9
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Quote:
Originally Posted by psoma View Post
Thanks @AmigaHope! Will give that a try.

@Jope: yeah, just a 1.3 boot Floppy with the Baseboard software at this stage. Getting an ide68k shortly.

And it does just look to be mapping the RAM in 512k chunks. Nothing particularly special going on, and certainly no CPU interfacing. I’m bummed as I have a VXL*30 accelerator in the machine too but it doesn’t have the RAM32 expansion in it that would give it 32 bit FastMem so I need to rely on the Baseboard

Cheers,

Tom
So you're going to try stacking the VXL*30 on top of the ide68k? What sort of case is this going into?

IMHO the best thing to do would be to just get an ACA500+ and deal with the system being a bit slower until you get a CPU upgrade for the ACA -- because your VXL is super neutered using the Baseboard -- piping all of your RAM access through the slow trapdoor/chip ram bus. Some stuff like storage etc. and anything RAM-intensive will actually run way faster on the ACA even just using its onboard 68000.

Unless someone figures out how to make a new VXL RAM-32 board.

Which reminds me, is having that limited chip memory causing you any problems? Not too much ECS software requires the maximum amount of 1M chip ram, even most stuff that on paper requires 1M of chip will run okay with 800k+ of it as long as you have some other ram too.

I'm asking because the baseboard is slow ram, everything on it goes through the chip ram bus, even the "fast" ram, so there's no performance improvement in running anything out of it vs. chip ram. The only reason you want stuff to go there is to free up chip ram for gfx/sound data, and not much software actually requires all 1M of chip ram to be free.

Last edited by AmigaHope; 28 December 2019 at 02:34.
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Old 28 December 2019, 10:06   #10
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Some good food for thought here AmigaHope!

To be honest, the speed isn’t a huge issue - I’m building this up for gaming with WHDLoad, so the 030 is good here as it provides the ability to hotkey quit, while the 4MB is probably borderline sufficient. I know a few of the games I’m interested in are “1MB Chip” versions, but to your point, I haven’t validated that 810k remaining is actually an issue. I guess I just wanted to know why it was behaving differently to the Furia 600 and you’ve answered that with some real insight.

Ultimately, I’m trying to do this neatly and on a budget. To that end, yes, I’m trying to keep this within an original 500 case and I think I have enough clearance to run another riser under the VXL. The ACA500 would be great, but adds a fair bit of cost.

Question: if I ditch the Baseboard and get the ide68k with 8MB mem68k option which sits under the CPU, will this give me *true* fast RAM? I could then populate the 4 empty slots on the 6A board to give me the 1MB Chip too...

Cheers,

Tom
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Old 28 December 2019, 10:59   #11
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Quote:
Originally Posted by AmigaHope View Post
The trick is the Gary board, which gives it access to the appropriate bus lines. The chip bus is perfectly capable of responding to accesses across all 24-bits of address space, it just normally doesn't. Getting under Gary lets trapdoor devices control this.
Ok, so otherwise it's just the "normal" method of fooling the Gary at various memory ranges.
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Old 29 December 2019, 00:14   #12
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Quote:
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Question: if I ditch the Baseboard and get the ide68k with 8MB mem68k option which sits under the CPU, will this give me *true* fast RAM? I could then populate the 4 empty slots on the 6A board to give me the 1MB Chip too...
Yes, the CPU socket is outside Amiga chipset-land so any RAM you put there will be true fast ram. You'll notice about a 30% performance improvement on average, with more like a 100% performance improvement on high-res 16-color displays or if you use a Graffiti device/Indivision for 256 colors.

You can even keep the baseboard as long as you adjust the memory mapping so it only uses 2M or so (512k as chip + 1.5 ranger mem), and just set the ranger memory as lowest priority, or assign it to a fix-sized ram drive or something.

My only concern is clearance + cooling inside the A500 case. If you are using the 50Mhz VXL*30 it will get SUPER toasty.
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Old 29 December 2019, 04:48   #13
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Awesome, thanks again mate am learning a lot!

With respect to the VXL, it’s just running the stock 25Mhz EC030.

Just thinking... if I take an alternate route and grabbed an A590, would I be able to add the Basebord’s 4MB to the 2MB on the 590? And would any memory mapper work, or do I specifically need to use the Baseboard one?

Cheers,

Tom

Quote:
Originally Posted by AmigaHope View Post
Yes, the CPU socket is outside Amiga chipset-land so any RAM you put there will be true fast ram. You'll notice about a 30% performance improvement on average, with more like a 100% performance improvement on high-res 16-color displays or if you use a Graffiti device/Indivision for 256 colors.

You can even keep the baseboard as long as you adjust the memory mapping so it only uses 2M or so (512k as chip + 1.5 ranger mem), and just set the ranger memory as lowest priority, or assign it to a fix-sized ram drive or something.

My only concern is clearance + cooling inside the A500 case. If you are using the 50Mhz VXL*30 it will get SUPER toasty.
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Old 30 December 2019, 00:58   #14
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Quote:
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Awesome, thanks again mate am learning a lot!

With respect to the VXL, it’s just running the stock 25Mhz EC030.

Just thinking... if I take an alternate route and grabbed an A590, would I be able to add the Basebord’s 4MB to the 2MB on the 590? And would any memory mapper work, or do I specifically need to use the Baseboard one?

Cheers,

Tom
On reviewing the Baseboard's manual (I had to go to archive.org to find it), it appears that if you only install 1.5M of slow ram onto it and don't bother with the Gary remapping, you don't need the memory mapping program at all and the OS will autodetect and allocate the memory on boot. If you do the 1M chip modification to the motherboard you might not even need the Gary board at all, provided you only populate 1.5M of RAM onto the trapdoor board.

The Gary board is needed to force the Amiga chipset bus to respond to Zorro memory space, something it normally does not do (because it was reserved for expansions via the side expansion slot on the A1000, which later became known as Zorro 1 when the A500 and A2000 were released, with Zorro 2 just being Zorro 1 with some bus arbitration added -- Zorro 1 is just the 68000 local bus).

So yeah you can add at least SOME of your memory to the A590. I really recommend you use a more modern expansion though as the A590 is super ancient. I guess if you have access to one for free though you can try this. If you do go to the A590 I strongly recommend you get a modern ROM replacement for the stock C= ROM as it dramatically improves its performance.

My main advice is to try to remove all Gary trickery from your Baseboard and let it just act as a ranger memory expansion.

Here's the Baseboard manual in case you don't have it:

https://web.archive.org/web/20180922...Manual-ENG.pdf
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Old 30 December 2019, 03:54   #15
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Legendary, thanks. Will update this thread on the ultimate outcome. Really appreciate your time and guidance!

Tom
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Old 30 December 2019, 09:53   #16
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You will always need gary trickery to get over 512k of RAM in the trapdoor.

The A590 fast RAM will coexist with 1.5MB of c00000 RAM just fine, as the 2MB inside the A590 will go into the zorro 2 memory area beginning from 200000.

It seems that the Baseboard would require a "B PAL" to be installed and have a wire soldered to JP2 on the motherboard for it to be able to function as a 1.5MB c00000 board that doesn't require an addmem command, so it is somewhat special. Too bad they didn't supply any kind of memory map in the manual.
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Old 01 January 2020, 23:21   #17
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Thanks Jope... I was looking to get 6MB of RAM so basically everything would work WHDLoad wise - is it not possible to get the 2MB of the A590 added to the 4MB of the Baseboard (and 512k base RAM)?

Cheers,

Tom
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Old 02 January 2020, 10:15   #18
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So you have it running at the moment? Please provide us with info on what address ranges the blocks of memory occupy once you have run the cRAM command.

You can browse the memory blocks in sysinfo and write them down, or if you have a 2.1 wb disk, showconfig will list the blocks too.
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Old 03 January 2020, 03:51   #19
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Thanks Jope... I was looking to get 6MB of RAM so basically everything would work WHDLoad wise - is it not possible to get the 2MB of the A590 added to the 4MB of the Baseboard (and 512k base RAM)?

Cheers,

Tom
I'm almost certain that any non-ranger memory on the Baseboard (above 1.5M~1.8M slow RAM depending on how the card does it) will conflict with the A590 because the A590 will assign its memory address with autoconfig into Z2 memory space, which won't know about the Baseboard also trying to put non-ranger memory in Z2 space.

i.e. don't fall too in love with your Baseboard as anything other than a ranger expansion.
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Old 03 January 2020, 14:07   #20
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OK, just fired the 500 up to get the RAM mappings in Sysinfo.... we have:

$00180000 - $001FFFF7: 511KB Fast RAM Priority 0
$00680000 - $006FFFF7: 511KB Fast RAM Priority 0
$00780000 - $007FFFF7: 511KB Fast RAM Priority 0
$00880000 - $008FFFF7: 511KB Fast RAM Priority 0
$00980000 - $009FFFF7: 511KB Fast RAM Priority 0
$00C80000 - $00CFFFF7: 511KB Slow RAM Priority 0
$00000000 - $000FFFFF: 1.0MB Chip RAM Local Public 24BitDMA Priority -10

I'm guessing, if there's no overlap with where the A590 maps its Fast RAM... it should see all 6MB, right?

Last edited by psoma; 04 January 2020 at 00:19.
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