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Disk/DDP questions


Captain Cozmos

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Instead of doing a ton of trial and error in an attempt to get things working I will ask you fine gentleman first.
 

I seriously need to know how deep into accessing these devices can I get without modifying bios's and such.

Is it possible through plain coding that I can change the way files are handled, directories and such.

 

I am going through the 1984 technical manual, I have a physical copy.  It explains the commands, the FCB and all but do they just send out predetermined commands to the 6801 and the 6801 fetch then that's about it?

No low level access to these things?

 

I have a formula for creating directories, sequential access as well as random.  I would like to implement something like a FAT table but again, I do not know how far I can go.

You get what I mean?

Half the DDP's are on the ADAM itself so they might be discounted but the disk drives seem to only respond to a preset type of instruction sent out over the ADAM Net and whatever returns is what you get.

 

I have no fear of changing the commands and FCB stuff but if it is a useless endeavor to do so then maybe I can take a hybrid approach that ADAM grabs the info and then I decipher it into the format I need but that will make file access a tad slower.

I read on FB from Eglostein?  An ADAM engineer that worked at Coleco that the DDP's 6801 did not have enough room for code to format the drive but he has one that will do it.
So what I gather is that these things can't go past their 6801 programing.

On the other hand as I understand is the Disk Drive 6801 is there and does nothing.  That everything is controlled through the BIOS.
Now if I were totally bold I could replace both the DDP 6801's on the ADAM and BIOS on the DDrive but that is me and not the average guy.

Edited by Captain Cozmos
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Here is something I am researching if anyone is interested.
An FPGA 6801 replacement.  The goal is to add a format function to the DD drives.
I have reached out to my colleagues at open cores and I have a 6801 compatible core to play with.
I could not find a MC6801U4 which has 4k which would allow me to add additional format coding but I will see what I can do.

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1 hour ago, else said:

Not sure where you get the idea that the disk drive 6801 does nothing.  It does a lot of stuff.  The 6801 listings are available here:

 

http://ann.hollowdreams.com/colfacts.html

Thank you for that the documentation list.
The Disk Drive 6801 from what I have read does basically nothing and has no programing, the EPROM on board does the work.
The other ones like the DDP are good.
 

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3 hours ago, Captain Cozmos said:

Thank you for that the documentation list.
The Disk Drive 6801 from what I have read does basically nothing and has no programing, the EPROM on board does the work.
The other ones like the DDP are good.
 

The 6801's used in the disk drives were pre-programmed digital data drive 6801 rejects with faulty code and were repurposed for use in the disk drive and hardware configured to remotely use code from an EPROM. The code my not be native in the 6801, but the 6801 is running the show, not the EPROM.

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