Re: MACH chip question

From: Rodolphe Pineau <>
Date: Tue, 23 Jun 1998 09:36:35 +0200

At 08:47 23/06/98 +0200, you wrote:
>I managed to delete your other message about Centurbo 2....
>> The AB040 take 9 cycle to acces the falcon mother board because the Mach
>> have to rebuild a 32 bits word with 2 16 bit one so They need 2 board acces
>> and each of them take 4 cycle plus one in the mach for concatenation. The
>> seems also that interupt are filter by the match but i don't know
exactly how!
>You said that the Centurbo 2 accesed the motherboard in 4 cycles and that
it should
>be faster. The difference is not very big if you are not only reading/writing
>16-bit words. A blocktransfer should be much the same.

Whatever the size of the transfert on the 040 bus is, it reads (or write) a
32 bits word. So if you make a move.b (a0)+,(a1)+ you've got 2 32 bits

>Also you said that the Cent2 could handle a transfer at 14MB/s to ST-RAM. How
>would that be possible when a normal Falcon can only do 5MB? It does also
>differn depending on which operation you do.

The CT2 boost the falcon bus speed to 25 Mhz so the bus transfert speed
grow exponentialy.

>Have you tried Nembench on the Cent2?
Yes (not me, but Centek does) and it geave 14 Mb/s for STRam transfert.

>Another small thing, you said that they choosed the 030 mainly for
>reasons. I don't realy see this as a "reason" as I have not got any problems
>with compatibility, the problem is Fast-RAM and not the CPU. Atleast I
have no
>problems with compatibility, but I guess I'm rare.

Yes there are less cache troubles on a 030 than on the 040 with the TOS

>Now, I would like to add that I think the Cent2 sounds like a very nice card
>and I would probably have got one if I hadn't got my AB040. But now when the
>possibility might turn up to add a 060 with L2 cache to my AB040 I wouldn't
>switch it against anything! I sure hopes it will work. :-)))
I agree with you. I've purchase an AB040 because i was fed up waiting for
the CT2

>> I don't think tha AB040 Mach PLDs alters boot instruction. If i remember
>> well only tos 4.04 work with the AB040 so i thing that there was a
>> modification in the begining of the rom so that AB040 mmu doesn't crash at
>> boot (because i thing this is the problems). I will take a look at an old
>> tos and make comparision between this old one and my 4.04 to chek what are
>> the differences.
>Have you looked at this?
Not yet. but i will take one week of holidays in about 3 week and take
some time to look for this and continue my exploration of the AB040
expansion bus pinout :-)

>> >As the AB040 hasn't got the fastest RAM access in the world, maybe it
>> >would be possible to change these 3 PLDs and make it faster. If someone
>> >just could get hold of those damned equations for the PLDs. It could be
>> >a interresting project for someone who has got lots of spare time...
>> >
>> I've got Mach databook so will take time to look if there is a solution to
>> read the internal code (may be not because of fuse protection)
>It would be interresting. It would also be interresting to know what is
>limiting the AB040 from using more than 64MB RAM. Maybe they didn't add logic
>for decoding all address lines?

I think that is the problem : no more free I/O pin on the Mach

>> >Also, do you happen to know anything about the expantion bus on the
>> >AB040? Is it just a plain CPU bus from the 040? Pinning?
>> I'm doing it and haven't finich it yet. This expantion bus have the upper
>> part of adress bus, and the lower part of data bus, There is some signals
>> that comme from one of the Mach that i haven't decode yet. In order to have
>> a real 32 bits bus we've got to use both trhe falcon expansioin port anf
>> the AB040 expansion bus. As soon as i've finish this work i will release
>> the pinout in this mailing list. I' could do this work but i haven't
>> enougth free time to buil any hardware for it.
>Great. Is this how the Cent2 works as well, "doubling" the old expansion bus?
Yes it use the old expansion bus plus a bus with the missing 030 signals
and i have the pinout of it ;-)

>If you need an idea for a great project, it would be very nice with a PCI
>interface connected to this 32-bit bus.... ;-)

Yes that's why i want the AB040 bus pinout :-))))

Rodolphe PINEAU
62, Bd Aristide Briand
77000 Melun FRANCE

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Received on ti. juni 23 1998 - 20:40:00 CEST

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