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Corvus Recovery Thread (Star Raiders 2 related)


doctorclu
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Curerntly in another thread of the intiial Star Raiders 2 release it was discussed that while the binary image of the game was playable, the source code of the most recent update was on a Corvus 6 MB drive.

 

Bob1200XL, who lives in the same area in California as the Corvus drive, was asked to help with the source receovery from the currently non-woirking Corvus drive. Bob asked for a new thread to be started to pool Corvus resources for the recovery project.

 

It was there Bob wrote:

 

"I have been talking to a guy that used to work at Corvus and he is willing to help. He does not know the Atari version, unfortunately, but he does remember many of the generic details about the systems.

 

Can we start a new topic on this? There should be some decent manuals for these drives. Do we have them?"

 

---------------------------

 

From here we can pool all resources and experiences in Corvus restoration.

 

To start this off, here is the more relevant Corvus manual I have found so far:

 

post-4709-0-59286000-1451850806_thumb.png

http://www.textfiles.com/bitsavers/pdf/corvus/7100-04703_B-Drive6mbSvc.pdf

 

(Also attached)

 

There were other Corvus manuals in this directory:

http://www.textfiles.com/bitsavers/pdf/corvus/

 

We welcome other information related to the Corvus 6 MB and information others can find on this topic.

 

Thanks!

7100-04703_B-Drive6mbSvc.pdf

Edited by doctorclu
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FYI, the programming information specific to the Atari interface is hidden in the COMU.ASM file of side 1 of the old SysGen disk, in the archive that Kyle22 posted. It's a nibble-wide interface. The platform-independent disk drive commands are documented in the Mass Storage GTI manual. The low-level interface is a relatively straightforward linear block read/write interface, much like Atari SIO-based disk drives.

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Here are the PDF's that I have for Corvus. I'm pretty sure they were all posted in threads by Fibrewire. If anybody sees anything useful that's not available somewhere else I'll be glad to post it up. I've probably renamed some of these from what they were originally named when posted. So some of the documents might seem to be different on casual inspection, but I think any naming differences should be evident with a little thought from anyone comparing.

 

post-6369-0-77806400-1451866081_thumb.png

 

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Just happened to have a Corvus 6MB drive up in the Attic. Spins up and comes Ready!

 

Finding the rest of this thing will be a little harder. Does anyone have/know of what else I need? There is some kind of card that interfaces to the Atari Ports. Can someone lend me a good set?

 

Bob

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Curious about the Corvus...

 

The entire system including the disks/platters are in the main box, except for the interface which is called the Integrator? Were the disk modules changeable inside the main box (like the disk modules on old IBM 360's) -- so the module is bad and Bob found one to swap out, and now he needs the Integrator to (hopefully) make it work?

 

-Larry

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The Integrator was basically an OS ROM replacement, so that you didn't need the Corvus boot disks.

 

The Corvus disk system consisted of an IMI hard disk, with an intelligent Z-80 based controller, which exposes an 8-bit data and control interface. This is then implemented on the various host adaptors in different ways, usually it's a straight buffered 8-bit interface, with the addition of a BOOT ROM of some sort, but in the case of the Atari, it was implemented as a bi-directional 4-bits at a time interface using the two joystick ports. It could have just as easily been implemented via the cartridge port, or with a bit of abstraction, as a slower SIO device. PBI wasn't an option yet.

 

(The controller itself had just enough bootstrap logic to load the first two cylinders on the disk, which contain the controller firmware, which can be upgraded.)

-Thom

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Another question...

In the Integrator docs, it mentions that a disk drive call is intercepted by the Integrator (OS) which decides if the call is for a floppy via SIOV or a call to a Corvus drive. Can someone tell me what I/O vector the Corvus uses (assuming it is that straight-forward)? I'm asking because I wrote A little Q&D benchmark for Fibrewire's Corvus that didn't work, presumably because it called SIOV for R/W. If I can gt the right vector, maybe I can get the benchmark working. The idea was to compare the transfer speed in the Corvus vs. newer hard drive systems.

 

-Larry

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The raw transfer rate will be significantly lower than the IDE interfaces, since the Corvus interface only transfers 4 bits at a time and requires a few steps to transfer each nibble. The driver I have does reads at 81 cycles/byte, or about 14KB/sec on a standard screen. In contrast, the IDE interfaces are exceeding 60KB/sec (they're actually faster than a memory copy). Add in the Corvus using a old disk drive with long seek times and slow rotational speeds, and I imagine the Corvus would be an order of magnitude slower.

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Just happened to have a Corvus 6MB drive up in the Attic. Spins up and comes Ready!

 

Finding the rest of this thing will be a little harder. Does anyone have/know of what else I need? There is some kind of card that interfaces to the Atari Ports. Can someone lend me a good set?

 

Bob

 

I've been reading this as we have received the input so far from everyone. Keep those ideas flowing.

 

I notice we tend to be on two points right now:

1) Giving the Corvus drive a few days to settle in it's environment.

2) The possibility of needing another good working interface card.

 

Is the second point still something you need Bob? If Fibrewire is open to lending his equipment to the project, that would be one possible source seven hours from your position. A good long drive I know, but listing known resources. Keatah was mentioned as a repairer of Corvus drives not sure where he lives.

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If it appears to be a problem in the interface card, we can talk directly to the drive controller. We do not need a fully functional disk system, just a way to dump all the sectors.

 

Here is a file that talks about the Z80 interface. We could 'roll our own'.

 

That said, yes, maybe Fibrewire will lend us his interface. We could duplicate an interface, also. Not sure that we need it at this point.

 

Bob

 

Corvus_Flat.pdf

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