Calabazam

As such, the ACA500 is perfectly fine since there is hope to use any 1200 boards even if they are not officialy supported (from the mere MTEC 1230 to the BPPC). Don't try to discourage Jens.
However, it would be better to keep compatiblity with the side slot expansion. There are some classic cool expansions like the A570 CDROM still interesting to use.

duga

You can use the A570 with your other, unexpanded, A500. I'm sure you have more than one A500.

TotO

Good answer.

Mr B

I don't have a first, let alone a second A500, so i'm not sure that's a good answer really. However, the ACA500 is equipped for CF's and atapi devices, so the A570 isn't really a huge dealbreaker, i think?
Also, if you guys are lucky, it's not going to be impossible to hack away at this, and remove the "blockage" to be able to use legacy add-ons. At which point Jens no longer has to provide support, you've modded his hardware way beyond spec, and everyone should be happy. Obviously i'm hoping for "artificial" blocking of the expansion port, meaning anyone could open it back up with a rotary cutting tool on a "multi-tool" type driver.

Time will tell. So far Jens have been VERY good to me, and provided not only a good speedboost to my A1200, but with it a size A memory upgrade, and add to injury, the Indivision MKII lets me play K-240 at home again. Still not on the Telly, but at least i'm playing again. My point is, don't take losses out in advance, you may yet be happily surprised.

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B!

Amiga 1200 with ACA 1230/56, Indivision AGA MKII, 4GB CF & 20GB HD (thanks Brian). Workbench 3.1. Otherways stock.
Future plans: None, right now.

TotO

Like said on the first page:
During the Amiga life, noboby take care about the fact that is was not possible to plug A570 with A590 with Supra 28... You have to make choices. Here, the choice is to add A1200 expansions.

In all cases, the A570 is like the CDTV drive. Today, no more work properly or will fail in few years.
It's more a collector item and the price to get it allow to buy a second A500.

Finaly, the ACA500 IDE controller will allow to connect a far cheaper, better and faster CD-ROM drive for peoples who always need that today...

TotO

$C00000 is slow mem, not fast mem.
Why not using the $200000-$9FFFFF memory space instead to get more real fast ram on the ACA500 board ?
Are you using this memory space with your ACA1220 card by doing a 16x8MB bank-switch (or using the MMU) ?

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alenppc

As Jens explained in another thread, his mapping of the fast ram to $c0 does not slow down the access to that ram. So it's just as fast as real fast ram.

kipper2k

If you use $200000 - $9fffff you will not be able to use an action replay cartridge as it conflicts

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TotO

I hope that is not the real reason.

kipper2k

I tried to use my cartridge with my 8mb expansion and the A500 won't initialise. once the expansion is removed the AR3 works, if i could change the code in the 8mb (and 4m) board to sit higher i would try it to see if it fixes the problem. I have the source if anyone can recompile it after changing the memory config code. It appears that the AR3 needs to start at mem address $400000

here's the code portion that defines the mem map of the expansion card.

// chip selector decoder
always @*
begin
casex( high_addr )
8'b001xxxxx: // $200000-$3fffff
begin
{which_ras[0],which_ras[1],which_ras[2],which_ras[3]} <= 4'b1000; // /RAS0
mem_selected <= 1'b1;
end

8'b010xxxxx: // $400000-$5fffff
begin
{which_ras[0],which_ras[1],which_ras[2],which_ras[3]} <= 4'b0100; // /RAS1
mem_selected <= 1'b1;
end

// remove this two CASE sections below for 4Mb only decoding (do not remove "default:"!)
8'b011xxxxx: // $600000-$7fffff
begin
{which_ras[0],which_ras[1],which_ras[2],which_ras[3]} <= 4'b0010; // /RAS2
mem_selected <= 1'b1;
end

8'b100xxxxx: // $800000-$9fffff
begin
{which_ras[0],which_ras[1],which_ras[2],which_ras[3]} <= 4'b0001; // /RAS3
mem_selected <= 1'b1;
end

default:
begin
{which_ras[0],which_ras[1],which_ras[2],which_ras[3]} <= 4'b0000; // nothing
mem_selected <= 1'b0;
end

endcase
end

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Mr B

I would think it's a good thing rather then a bad. Instead of going with a obvious address space, go with one not so obvious, and maintain compatibility with as much old hardware as possible.
Especially as the not so obvious address space isn't really a problem.

__________________
B!

Amiga 1200 with ACA 1230/56, Indivision AGA MKII, 4GB CF & 20GB HD (thanks Brian). Workbench 3.1. Otherways stock.
Future plans: None, right now.

T_hairy_bootson

Doesnt the AR plug into the side port anyway?

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TotO

ACA500 does not allow any other expansion than a chipmem expansion.
The lower 68000-adapter will block the 86-pin port to send a clear message: Nothing allowed here.
Further, the 68000 socket will have to be empty, otherwise the mechanical mounting concept won't work.

It's why I ask (post #106), why not using the $200000-$9FFFFF memory space instead to get 4/8MB fast RAM on the ACA500 board to avoid to buy the ACA1220 if not needed.
(except if the ACA1220 expansion use it as 16x8MB back-memory or virtual address space)

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Schoenfeld

ACA500 is a 14MHz card. If you add fastmem on the 86-pin port, it's going to be slow (7MHz). Also, as I wrote numerous times before, I don't support anything that may be connected to the 86-pin or other ports of the A500. The card is extremely low-cost and can only be that cheap if it works out of the box. As soon as the customer adds other stuff, it's either fully supported by iComp and resellers, or you're on your own. Since the "on your own" part pretty much always ends up on my desk, I make it mechanically impossible to make mistakes.

Here's some info on how fast the ACA1220 (16.67 MHz) will be:


Overclocking is possible but not recommended and not guaranteed:


I have also attached the AIBB modules to this message.

Jens

Attached Files

ACA1220.LHA (1.1 KB, 38 views)

Methanoid

Thanks Jens... I know OC is a bit of luck but how easy is it to do... I know nothing of your designs but is it a case of changing a jumper, soldering or software selectable?

I've a Blizzard 1220 which is 28mhz 020 4Mb but maybe an ACA1220 with a little overclock but all that extra Ram might be better....

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fitzsteve

You need to change the clock crystal, desoldering four throughole points and fit a socket (soldering 4 points) and then you can experiment till your heart is content. If you put a clock too high hopefully there is no damage, just wont boot

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Schoenfeld

It's not software-selectable, but putting a wire link between two spots. This will change the CPU clock divisor from 3 to 2. The crystal on the board is 50MHz and remains in place. The design is fully async, meaning that the CPU runs async to the A1200 and the memory controller runs async to the CPU.
Could you do the same tests that I have made? I mean bustest and sysinfo. I'd like to know how much faster the Blizzard 1220 is.

Jens

TotO

OK, thank you!

ikonsgr

I just wondering: From what i unsderstand so far, the on board 2mb ram of aca 500 is not fast ram (it's not reside in the 8mb pooll starting at $200000 right?) , is it possible then, to use it in joint with a fast ram card like perhaps, this one?

TotO

Like said by Jens, it's not possible because the mounting system don't allow any expansion on the CPU or the side expansion slot.

But, in theory it's address compatible...
Just you will have physical problems to add both on your computer.

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