A590 and Guru ROM V6.xx Compatability

[Runey]

Does anyone know if the Guru-ROM v6 works with the A590?

I know it's meant to work with the A2091, so I would have thought it would work with the A590.

However I read this FAQ and it suggests that I need to change my DMAC (part 390563) from rev 1 to rev 2. But as far as I understand the A590 and A2091 never came with a rev 2 DMAC, only the A3000.

http://wuarchive.wustl.edu/pub/amine...lp/a590faq.txt

Anyway the question is can I use the Guru-ROM with my A590 without changing the DMAC? If so I know I can download the actually ROM image (it's now PD) but does anyone have any details on the adapter PCB used to actually fit the ROM?

Hope someone can help

[Jope]

It works, but the metal RF shield won't fit on.

The A590s have come with a REV2 DMAC, I had one. (now the DMAC is sitting in my A2091's socket)

And about the GURU ROM DMAC requirements.. What did the FAQ say? I can't remember any more.. IIRC it does require a DMAC-2, the SCSI chip revision is not important, but better results with a rev8 chip.

Please tell me about the adapter PCB too once you find out the GAL equations. :-)

[Runey]

Hey Jope

No probs about the RF shielding. I was going to (eventually) tower my A500 anyway.

Here's what the FAQ says about the DMAC

Q: Does Guru-ROM V6 have any specific hardware requirements?
A: The DMAC chip on your controller needs to be revision 2.
It's easiest to check this using "ShowConfig". The right
kind of DMAC would show up as "Prod=514/3" in the output.
If you really insist on checking out the actual chip, it's
the big, square Fat Agnus-lookalike chip right about in the
middle of your controller. It should be labeled "390563-02".
It's quite impossible to miss it: just look for the biggest
chip! Other than that, Guru-ROM V6 will happily run on any
680x0 processor (even on Kickstart 1.3), and there's no
need for a new SCSI controller chip either!

Here's what the FAQ says about the SCSI controller

It doesn't seem to make a difference, whether your SCSI bus adapter
chip is a 33C93A (better of the two) or a 33C93 (worse of the two)
under the Commodore ROM's. Under Guru-ROM V6, the difference for
33C93A's favor is _significant_ (~220%) speed increase.

Well it really sucks that it needs a rev 2 DMAC. I can't find one anywhere. Later rev 8 SCSI controllers are a dime a dozen (well not that cheap but at least easy to get). If anyone knows where I can get a rev 2 DMAC that'd be great

Also anyone got any pics of the Guru-ROM. Once I see one I should be able knock up a PCB adapter.

[Jope]

It's not a simple wiring job, the address lines are switched with a GAL.

If you want a picture, think of a piece of PCB with a socket on top for the PROM and spikes coming out of the bottom to connect to the board. :-)

[Runey]

Nothing is ever easy it Well my search continues

[alexh]

I would imagine that if you are making your own EPROM, then you could use two smaller EPROMS that are pin-compatible with the existing ones and avoid the need for the ROM adapter at all?

The only reason I can imagine they did this ROM adapter at all was: 1)It was cheaper 2)You cannot get pin-compatible EPROMS?

[alexh]

Originally Posted by Runey

Well it really sucks that it needs a rev 2 DMAC. I can't find one anywhere. If anyone knows where I can get a rev 2 DMAC that'd be great

Not sure if it is the correct Packaging but Centsible sell them

http://www.centsible.com/cgi-bin/car...txt&search=~O~

Make sure you want the PLCC version and not some strange DIP variant

[cebulba]

Originally Posted by alexh

Not sure if it is the correct Packaging but Centsible sell them

http://www.centsible.com/cgi-bin/car...txt&search=~O~

Make sure you want the PLCC version and not some strange DIP variant

DON'T BUY AT CENTSIBLE!!!!
READ THIS: CENTSIBLE THREAD ON EAB

New OWNER isn'T able to handle store until today!

[Jope]

Originally Posted by alexh

The only reason I can imagine they did this ROM adapter at all was: 1)It was cheaper 2)You cannot get pin-compatible EPROMS?

But the actual reason is that the chip is larger than the original, and there are not enough address lines going to the socket.. Hence the additional address line needs to be decoded with some logic.

In Amiga related hardware, the only really rare pin layouts are in the kickstart ROMs..

[Runey]

Is the Super DMAC compatible with the other DMAC chips? It's part number 390537-02 and was used in the A3000. All the other DMACs rev 1, 2 and 4 all have part numbers 390563-0x. If it is compatible thats great There are several places that sell it (one even in Australia OMG ) Well time to do some more Google trawling

Oh and about Centsible and Softhut. Centible seem to have good prices (not if you never receive what you pay for though) but Softhuts prices are a thing to behold (wasn't sure if I should laugh or cry)

[Jope]

That's a good question. I'm under the impression that it is a different beast.

Please report back here if you find out, I'd like to know that for sure too.

[Runey]

Well I just got an e-mail back from Ralph Babel, the creator of Guru-ROM (at least the code portion anyway). He said that a rev 2 DMAC is definately needed. Also said that there was never an adapter for the A590 (because of height problems) but I'm sure the A2091 one would work. The recommended EPROM is a 27256.

More info to come (I hope)

[Jope]

That's what I meant with the RF shield not fitting.. The A2091 and A590 share the same electronic design.

[alexh]

Originally Posted by cebulba

DON'T BUY AT CENTSIBLE!!!!

I would say that in this case, 1 item, unavailable elsewhere, you have to go for it! But as I said make sure you need the PLCC version and not some other variant.

However I have found another *possible* source of them:

http://www.mrhardwarecomputers.com/data/archive.htm

But there is a chance they have sold out.

[alexh]

I've just checked and you do need the PLCC version

[Runey]

I would risk Centsible if I was confident that the Super DMAC rev 2 was compatible with the DMAC rev 2. I have e-mailed them to get a part number. Though I may have found someone who has one in his "shed". Waiting for an e-mail back.

I have had a look at the old EPROM (2764) and the new EPROM (27256) and they are virtually pin identical. Main difference is two additional address inpputs on the new one (27256).

Spoke to someone who used to have a Guru-ROM and they said there was an IC on the bottom of the adapter. Obviously to handle the difference in address lines. If I could find out what the IC was I confident I could make a new Guru-ROM now.

Back to my searching

[alexh]

I am guessing that it will be a GAL or PAL for paging. So it's not just what chip, but the code inside it.

If you ever do work out how to make the ROM adapters or where to get them from cheap, I would be interested in making one for my GVP A500 HD8+ II

[Jope]

A friendly person called Moof provided me with the following info:

http://jope.fi/gururom1.png
http://jope.fi/gururom2.png

27C256  GAL16V8
~~~~~~~~~~~~~~~
1       18      Vpp/A15 (cut)
2       2 i     A12
3       3 i     A7
4       4 i     A6
5       5 i     A5
9       7 i     A1
10      8 i     A0
14      10,11   GND
20      13 (i)  CE\
21      14 (i)  A10
22      15 (i)  OE\
23      9 i     A11
24      16 (i)  A9
25      6 i     A8
26      12 (i)  A13
27      19      A14 (cut)
28      20      Vcc
        1(i),17

Now if only someone could get the GAL binary. (has anyone tried asking the author?)

[Runey]

Well done Jope that's awesome

I've e-mailed Ralph Babel and hopefully he'll be forthcoming with the GAL program.

So once we get that, we'll have all the info we need to make out own Guru-ROMs

Keep your fingers crossed he's feeling generous

[Jope]

Originally Posted by Runey

Well done Jope that's awesome

I can't take credit, it was Moof who did it. :-)