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Thread: 8MB ROM SIMM and EDisk driver


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Permlink Replies: 27 - Pages: 2 [ Previous | 1 2 ] - Last Post: Aug 10, 2014 11:39 PM Last Post By: bbraun Threads: [ Previous | Next ]
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Jan 24, 2013 9:09 PM   in response to: tt in response to: tt
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Thanks for testing that. I've got a Turbo601 on the way, which isn't the same as the Turbo040, but I'm hoping it's similar in its approach. I'll take a look when it arrives.
tt


Posts: 145
Registered: 8/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Jan 24, 2013 10:05 PM   in response to: bbraun in response to: bbraun
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Cool, perhaps in your probing of the 601, you might find why it does not work with an SE/30. Is there a ROM/firmware dump of it around?
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Jan 24, 2013 11:01 PM   in response to: tt in response to: tt
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Yeah, it should be interesting. I'm not aware of rom dumps floating around, so I'll just have to wait until it arrives. From pictures, it appears to have 4 ROM chips soldered on. I probably won't want to desolder those, but hopefully they're accessible from in-system.
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Jan 28, 2013 11:24 PM   in response to: bbraun in response to: bbraun
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The Turbo601 arrived, but unfortunately it seems to take a different approach. It looks like it uses a 4MB licensed ROM, rather than modifying the system ROM.
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Mar 22, 2013 2:11 PM   in response to: bbraun in response to: bbraun
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I managed to get a Turbo040 and check it out.
It has a modified version of the original ROM at 0x40800000, and this extends for 1MB.
It then has the 1MB ROM from the Turbo040 mapped immediately after that at 0x40900000.
In theory, the remaining 6MB of the ROM SIMM should be addressable after that, but because the physical location 0x40800000 is no longer logical address 0x40800000, and has been replaced by the Turbo040, accesses to 0x40B00000 and beyond are invalid and are not mapped to the ROM SIMM anymore.

This could, in theory, be resolved by a modified version of the Turbo040 ROM, but I'm not sure that's really worth the time & effort.
JDW

Posts: 8
Registered: 1/13/13
Re: 8MB ROM SIMM and EDisk driver
Posted: Mar 22, 2013 6:25 PM   in response to: bbraun in response to: bbraun
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bbraun wrote:
This could, in theory, be resolved by a modified version of the Turbo040 ROM, but I'm not sure that's really worth the time & effort.

Since a modified version of the Turbo040 ROM could in theory also resolve the 1.4 MB floppy Read/Write problem (which occurs on an SE/30, and possibly other Macs too, when a non-stock ROM is used), I would say the time and effort would not be in vain.

If you disagree, then perhaps you should consider making the effort a for-pay kick starter project, and then alert Turbo040 owners to it via a post on the 68kMLA. Money has its way of getting otherwise reluctant projects off the ground. And I for one feel that such a project would be one of the most exciting that has hit the vintage Mac community in recent memory. I have little doubt that if Turbo040 owners out there were aware of the project, they would support it.
tt


Posts: 145
Registered: 8/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Mar 22, 2013 7:09 PM   in response to: bbraun in response to: bbraun
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Does anyone have the the most recent version of the ROM? I believe it is 4.11 according to Artmix: http://www.artmix.com/turborev.html. I am guessing all the versions do something similar to what bbraun has described, but it might be worth seeing if other versions behave differently. Please PM me or post if that is OK with the mods. Thanks.

ROM hacking by bbraun and dougg3 have by far been the most interesting hacks in the past decade for this era of hardware. =)

What would be the max size flash chip you can fit in the Turbo? Could it be exploited to provide more room or introduce a flash drive?
JDW

Posts: 8
Registered: 1/13/13
Re: 8MB ROM SIMM and EDisk driver
Posted: Mar 22, 2013 7:42 PM   in response to: tt in response to: tt
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Trag always offered the latest 4.11 ROM on the Turbo040's he used to sell:

http://68kmla.org/forums/viewtopic.php?p=51478#p51478

Any my own card has the 4.11 ROM too:

http://68kmla.org/forums/viewtopic.php?p=51286#p51286

Complexhvac

Posts: 5
Registered: 3/25/13
Re: 8MB ROM SIMM and EDisk driver
Posted: Mar 25, 2013 10:33 AM   in response to: bbraun in response to: bbraun
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Hi Rob,

I have applied many of your generous offerings relating to the Classic Macintosh platform. The advancements made by you & Doug have been nothing short of miraculous. I was compelled to purchase & support the 8MB ROM SIMM programming package offered by Doug & the vital ROM Disk Images rewritten by yourself! I have been quite lucky to have been able to restore (1) Macintosh IIci & (2) SE/30s that benefit from the many offerings relative to your website Downloads. Many Thanks to both of you for your continued support & advancements regarding these old relics of ours!

I must say, the fact that you have currently acquired a DayStar 040 Accelerator Card has my undivided attention. This is the ultimate upgrade for my restored Macintoshes listed above, which I am fortunate to have acquired for both! To be able to apply the ROM SIMM upgrade to these would be awesome indeed, as JDW has also been hot on your heels to request the rewrite of the 040 ROM Code. I'm with JDW on the monetary support relating to a fix, as we know there has been no one capable before you in this arena, please don't give up on us, the WOW Factor is extremely high in regards to this one! Could you be so kind as to pursue a workable solution, as we have not seen anything like this before.

Again, count me in on a monetary fee if that is what is needed to proceed! I'm sure there will be many others onboard with this one!

Looking forward and with most anticipation,

Complexhvac

Michael

Message was edited by: Complexhvac

Message was edited by: Complexhvac
JDW

Posts: 8
Registered: 1/13/13
Re: 8MB ROM SIMM and EDisk driver
Posted: Aug 8, 2014 9:49 PM   in response to: tt in response to: tt
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My last post here was March 2013. It's now August 2014. Was anything done with regard to Turbo040 (or accelerator in general) compatibility?

I myself seek not merely "accelerator compatibility" but also a possible fix for the 1.4MB floppy problem I describe here:
https://68kmla.org/forums/index.php?/topic/235-which-is-better-daystar-powercachemicromac-diimo/#entry2465

Thanks.
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Aug 8, 2014 10:56 PM   in response to: JDW in response to: JDW
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I haven't done anything further with the turbo040. I believe I left it in the "more trouble than it's worth" bucket after having started disassembling the turbo040 ROM to get a feel for the scope of the problem.
JDW

Posts: 8
Registered: 1/13/13
Re: 8MB ROM SIMM and EDisk driver
Posted: Aug 8, 2014 11:40 PM   in response to: bbraun in response to: bbraun
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What would make it worth your trouble?

:-)

(Or were you implying that it is "next to impossible"?)
bbraun


Posts: 493
Registered: 7/25/12
Re: 8MB ROM SIMM and EDisk driver
Posted: Aug 10, 2014 11:39 PM   in response to: JDW in response to: JDW
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I don't view it as impossible, just time consuming, most likely involving both a custom ROM SIMM on the machine and a custom ROM on the turbo040 card. My vague guesstimate on project scope is something on the order of "more than I have time off from my job". Short of 68k hacking becoming a full time job, I'm not sure I see the project coming together.

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