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Mathy

What's so special about the 815?

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Hello guys

 

Where does the 815 differ from the 810 and all other Atari 8 bit drives? Not counting rarity factor!

 

Sincerely

 

Mathy

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Besides it being bloody rare, it's double density ONLY - no single density. And it writes it's data binary inverted, so it's not compatible with the dd drives that came out from other vendors. Probably also due to the rarity, as 3rd parties woudlnt have even have had access to one to test...

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The 815 can't do single density? So it can't play any games (which were almost all released in SD since that was... until I just read that.... the "common denominator")?

 

Wow... I didn't even know that. I thought it was literally just 2 810's shacking up.

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The code in the ROM is indeed coded to only support MFM encoding, so it's incompatible with FM used by the 810. So yeah, all commercial software would not work unless they made an 815 version.

 

Never seen one myself, just remembering some old threads where this was explored... Bob Wooley mentioned about the data inversion here: http://atariage.com/forums/topic/224072-percom-at88-s1pd/?p=2967973

and a thread about the 810 ROM source code shows evidence of ambitions for other features that were not finished like double sided, 80 tracks, and 38.4kbps SIO speed support. Cool to think the engineers were thinking about this in 1980: http://atariage.com/forums/topic/78379-atari-815-controller-source/?p=2594414

Actually the 815 DOESN'T invert the bits, but the 810 and every other drives DD do... The original DOS 2.0D that came with the 815 didn't have the "P" option to switch density, because it couldn't... that was added by companies like PERCOM that later had drives that could switch between Single/Double. In theory the 815 could natively read PC 180K disks.

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i wonder if it was intended for running a BBS or another non-mainstream purpose?...

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The code in the ROM is indeed coded to only support MFM encoding ...

 

That's why I thought for quite some time. But after seeing the schematics you realize that the incompatibility is much more difficult to solve. The 815 doesn't use a high level WD FDC as most other Atari drives do, neither a PC compatible one (Intel or Nec). Decoding is performing mostly with discrete components and a circuit specifically designed for MFM. It would require a major board redesign, almost the whole digital section from scratch, to get FM encoding compatibility.

 

No wonder that the project was cancelled when management find out.

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Id just like to know who created this awful design and how it got so far along before some realized what a total POS it was. Then again the 5200 joysticks made it to production - maybe the same designer?

Edited by Goochman
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i wonder if it was intended for running a BBS or another non-mainstream purpose?...

The 815 was designed for business software. There are several unreleased business programs (accounting, finance, etc) that require the 815. Both were killed off when Atari decided to stop marketing the 800 as a business computer.
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Hello Tempest

 

Luckybuck is trying to archive most of these old business programs. Some require the 815. That's why I'm asking what's special to the 815.

 

Sincerely

 

Mathy

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Hello guys

 

Let's see what we have 'til now:

 

The 815 is:

 

- Double Density only

- Two drives in one

- None inverting

 

Does it have one or two heads per drive?

 

Sincerely

 

Mathy

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Each drive has one head - but, the PCB has circuits for two heads per drive. There are no components mounted for the extra two heads, however.

 

Bob

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And it‘s a monster sizewise

A stack of two 815s and an 820 would probably reach desk height and certainly dwarf period monitors.

 

It‘s certainly a lot bigger than some of the few other dual drives.

 

It‘s interesting that the 815 made it into lots of marketing literature without being actually available.

 

I didn‘t know it couldn’t read 810 SD floppies which strikes me as a strange design decision.

 

 

Gesendet von iPhone mit Tapatalk

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Hello guys

 

So if some piece of software says an 815 is required, it probably (actually?) means that you could use any drive as long as it supports double density (256 byte sectors) and does not invert data?

 

Sincerely

 

Mathy

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@Mathy: First thank you so much Mathy for opening this case. I knew this is still a hard one, but not that hard. OMG...

 

@all: Let's assume, we just have a few days to get a 37 year old, lost to believe software, which is on 815 DD format with double index holes and defect sectors, what actually can be done to preserve them?

The Kryo will fail, due to double index holes. The Happy can copy the disk, but not the defect sector in DD format. Please help, it is very urgent and we may never get a 2nd chance.

 

Thank you all so much in advance.

 

@Tempest: You wrote:

"

The 815 was designed for business software. There are several unreleased business programs (accounting, finance, etc) that require the 815. Both were killed off when Atari decided to stop marketing the 800 as a business computer.

"

Please correct me, if I am wrong, but there is the Atari Accountant only, which requires a 815, no program else.

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20Word%20Processor

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20Personal%20Financial%20Management%20System

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20The%20Dow%20Jones%20Investment%20Evaluator

(if anyone out there has just any(!) trace for box CX412, besides the listed ones, please let AtariWiki know, otherwise, we must assume, it was announced, but never realized and therefore must be treated as a cold case, which is sad)

 

Do you have further knowledge on how Atari decided to stop marketing the 800 as a business computer?

Edited by luckybuck

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@all: Let's assume, we just have a few days to get a 37 year old, lost to believe software, which is on 815 DD format with double index holes and defect sectors, what actually can be done to preserve them?

The Kryo will fail, due to double index holes. The Happy can copy the disk, but not the defect sector in DD format. Please help, it is very urgent and we may never get a 2nd chance.

 

Use the SCP, instead of the Kryo, without index mode. The SCP can dump flippy disks without index hole, which means (I assume, didn't test it myself) with too many index holes as well.

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You mean: SuperCard Pro?

 

Yes, it should work. Then send me the raw flux level dump and I might be able to recover the damaged sectors.

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@Mathy: First thank you so much Mathy for opening this case. I knew this is still a hard one, but not that hard. OMG...

 

@all: Let's assume, we just have a few days to get a 37 year old, lost to believe software, which is on 815 DD format with double index holes and defect sectors, what actually can be done to preserve them?

The Kryo will fail, due to double index holes. The Happy can copy the disk, but not the defect sector in DD format. Please help, it is very urgent and we may never get a 2nd chance.

 

Thank you all so much in advance.

 

@Tempest: You wrote:

"

The 815 was designed for business software. There are several unreleased business programs (accounting, finance, etc) that require the 815. Both were killed off when Atari decided to stop marketing the 800 as a business computer.

"

Please correct me, if I am wrong, but there is the Atari Accountant only, which requires a 815, no program else.

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20Word%20Processor

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20Personal%20Financial%20Management%20System

https://atariwiki.org/wiki/Wiki.jsp?page=Atari%20The%20Dow%20Jones%20Investment%20Evaluator

(if anyone out there has just any(!) trace for box CX412, besides the listed ones, please let AtariWiki know, otherwise, we must assume, it was announced, but never realized and therefore must be treated as a cold case, which is sad)

 

Do you have further knowledge on how Atari decided to stop marketing the 800 as a business computer?

 

I thought it was more than just the Atari Accountant but that just might be my fuzzy memory. Let me do some research. But it looks like you've looked into it more than I have.

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Hi Tempest, your memory is better then mine, I even don't know, that I do know... or vice versa ;-)

 

Yes, would be cool. Thank you so much in advance. What bothers me the most, is the fact, that we do have not just any trace of the CX412 box. Just ads, nothing more. Regarding the CX401, I have clear evidence and I know 2 users in the US, who have the box for sure. At the weekend, we have discussed the issue on a general meeting here in Germany. That won't be an easy one. I am totally with ijor, it might owrk, but it is not for sure. So have the need for Hannibal Smith or even better Jim Phelbs plan to get it digitized...

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That won't be an easy one. I am totally with ijor, it might work, but it is not for sure.

 

I don't expect much problems with a SCP. As I said I didn't try myself, but it probably ignores index holes completely when dumping disks with blind (non Index) mode. In the worst case, you can just disable the index holes altogether with a tape on the jacket index hole, or on the drive, and this will be like dumping a flippy disk which is known to work with the SCP. But I doubt you would need to go that far, I believe the SCP was used to dump hard sectored disks which have many index holes.

 

Regarding the damaged sectors I can't comment until seeing the raw flux level dump.

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Thank you ijor, yes, I think you have solved it. Now, I must find someone out there in the galaxy, who joins the VCF East with a SCP... Further, I will add all the findings, we have so far. Thank you.

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