Author Topic: HD Disk Drives  (Read 845 times)

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Offline ComSoft6128

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HD Disk Drives
« on: 18:35, 04 March 18 »
As far as I know no 3.5" HD disk drives were ever available for CPC. At the time (early 90's) I understood this was because the CPC hardware would not support these drives. How difficult would it have been to build a hardware add-on that would have allowed this or would it have been an impossible project?
And yes I know there was no OS at the time that would have allowed this.

Cheers,

Peter

Offline IanS

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Re: HD Disk Drives
« Reply #1 on: 18:47, 04 March 18 »
There were a couple made. (though probably late in the life of the CPC)

http://www.cpcwiki.eu/index.php/Dobbertin_Harddisc
http://www.cpcwiki.eu/index.php/Vortex_Winchester_Drive

Offline ComSoft6128

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Re: HD Disk Drives
« Reply #2 on: 18:59, 04 March 18 »
Sorry,

Should have made that clearer - 3.5" 1.44MB (HD) disk drives.
« Last Edit: 19:00, 04 March 18 by ComSoft6128 »

Offline GUNHED

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Re: HD Disk Drives
« Reply #3 on: 20:03, 04 March 18 »
As far as I know no 3.5" HD disk drives were ever available for CPC. At the time (early 90's) I understood this was because the CPC hardware would not support these drives. How difficult would it have been to build a hardware add-on that would have allowed this or would it have been an impossible project?
And yes I know there was no OS at the time that would have allowed this.

Well, I don't know about a 3.5" inch HD drive, you would need to double the frequency for the FDC765, which makes it HD compatible.

It's a bit more easy to use 5.25" HD drives (various reasons, f.e. rpm, power of magnetization of disc etc.). One of my CPCs is still using a 5.25" HD drive, but it needed some modding, for example the generation of a Ready-Signal which isn't trivial if you do it right. Oh, and there is an OS supporting this.
http://futureos.de --> Get the revolutionary FutureOS (Recent update: 2018.08.23)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Ver.: 2018.08.15)

Offline rpalmer

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Re: HD Disk Drives
« Reply #4 on: 23:35, 04 March 18 »
The reason the CPC cannot use HD floppy drives is that the CPC cannot transfer the data fast enough to fit within the specifications for such capability.

rpalmer

Offline GUNHED

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Re: HD Disk Drives
« Reply #5 on: 12:49, 06 March 18 »
The reason the CPC cannot use HD floppy drives is that the CPC cannot transfer the data fast enough to fit within the specifications for such capability.

rpalmer


Actually the CPC can. At least my floppy routines can. However the FDC need to be fed the double frequency. The 5.25" high-density floppy I'm using runs with 0.7 MB Vortex format, but with higher magnetisation (so you can't write on disc with other regular 5.25" DD floppies).


The time needed to transfer one byte in HD is about 12-13 us. That's not the problem. The FDC needs the double frequency. This was tested successfully too.

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Offline rpalmer

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Re: HD Disk Drives
« Reply #6 on: 14:12, 06 March 18 »
GUNHED,

What i said was true for an unmodified disc interface.

That being said I guess the disc interface could have been modified to handle the HD discs. What exactly was done to achieve this? Do you have pictures?

It make me wonder why the CPC was not updated to handle HD discs with say 3.5 inch drives used in the PCW 9* series to get 1.44MB capacity if all that was needed were changes to the interface.

rpalmer

Offline KaosOverride

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Re: HD Disk Drives
« Reply #7 on: 16:24, 06 March 18 »
Amiga HD floppy drives slowed down from 300 to 150 rpm and the data was saved as DD drives but the sector was double lenght.


I have try to find an HD drive which can slow to 150 but.... They are very rare to find  :-[

Offline Bryce

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Re: HD Disk Drives
« Reply #8 on: 16:32, 06 March 18 »
It make me wonder why the CPC was not updated to handle HD discs with say 3.5 inch drives used in the PCW 9* series to get 1.44MB capacity if all that was needed were changes to the interface.

rpalmer

Because HD only came out in 1987 and the modification isn't a simple matter of swapping some parts by the user. Why would they invest money in a complicated hardware/firmware modification for an "old" computer when they should be putting all their resources into new products?

Amiga HD floppy drives slowed down from 300 to 150 rpm and the data was saved as DD drives but the sector was double lenght.

I have try to find an HD drive which can slow to 150 but.... They are very rare to find  :-[

Have you tried the Amiga forums? :D

Bryce.

 

Offline ComSoft6128

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Re: HD Disk Drives
« Reply #9 on: 17:48, 06 March 18 »
Hi Guys,

I was thinking more of the external 3.5" B drives that were then available from Siren Software and other companies.

Cheers,

Peter

Offline Flonky_Tash

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Re: HD Disk Drives
« Reply #10 on: 15:52, 24 April 18 »
Well, I don't know about a 3.5" inch HD drive, you would need to double the frequency for the FDC765, which makes it HD compatible.

It's a bit more easy to use 5.25" HD drives (various reasons, f.e. rpm, power of magnetization of disc etc.). One of my CPCs is still using a 5.25" HD drive, but it needed some modding, for example the generation of a Ready-Signal which isn't trivial if you do it right. Oh, and there is an OS supporting this.


Gunhead,


Out of curiosity, how did you generate a ready signal on your 5.25" HD drive? I have a couple of HD 5.25" units lying around that I want to get working with the cpc and they don't have a RDY jumper option. I was thinking of soldering pins 33 and 34 on the flat connector together. Do you reckon that would work? Obviously I'd make sure I solder it as flat as possible so I can fit the cable on it.
If it isn't broken - make it better.

Offline GUNHED

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Re: HD Disk Drives
« Reply #11 on: 17:19, 24 April 18 »
Oh, please never short the Ready-signal, quite some software depends on it.

IIRC the trick is to wait until the FDD reaches its regular RPM then sense one or two things, but I have to find the schematics. Some quite sophisticated ways are described in some older computer magazines.


EDIT: Wasn't there a thread about it?

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Offline Flonky_Tash

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Re: HD Disk Drives
« Reply #12 on: 18:38, 24 April 18 »
Oh, please never short the Ready-signal, quite some software depends on it.

IIRC the trick is to wait until the FDD reaches its regular RPM then sense one or two things, but I have to find the schematics. Some quite sophisticated ways are described in some older computer magazines.


EDIT: Wasn't there a thread about it?


Thanks for the advice! Was just speculating because shorting the RDY signal is required to get 3.5" drives working


There was indeed a thread about this a while ago yes. However, I think that was solved because the drive in question had the right jumpers to play around with....I THINK.
If it isn't broken - make it better.

Offline GUNHED

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Re: HD Disk Drives
« Reply #13 on: 21:42, 25 April 18 »
Thanks for the advice! Was just speculating because shorting the RDY signal is required to get 3.5" drives working


That's a common misunderstanding, most of the software will run with it, but for example CP/M Plus (and it's tools, like DISCKIT3.COM), FutureOS, SymbOS and some demos / games will not run.


Good luck anyway :-)

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Offline rpalmer

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Re: HD Disk Drives
« Reply #14 on: 00:04, 26 April 18 »

That's a common misunderstanding, most of the software will run with it, but for example CP/M Plus (and it's tools, like DISCKIT3.COM), FutureOS, SymbOS and some demos / games will not run.


Good luck anyway :-)

The reason why some software will not work is that they check the "Ready" line first before starting the drive (knowing that the drive was not spinning), rather than request spinning up the drive and then waiting for the ready signal to go active.

Both are valid if the drive has a ready signal which is set by the drive.

rpalmer

Offline GUNHED

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Re: HD Disk Drives
« Reply #15 on: 15:25, 26 April 18 »
The reason why some software will not work is that they check the "Ready" line first before starting the drive (knowing that the drive was not spinning), rather than request spinning up the drive and then waiting for the ready signal to go active.


Maybe in some cases (which I don't even know). But FutureOS does it the other way around: First at all it starts the FDD motors, then other things happen, then it waits until the drive states "Ready". This is the quickest and most efficient way to save time. Most other DOS just wait a defined time then they assume "Ready", in this case a Ready-Shortcut would work, but it's just a dirty hack.
SymbOS probably does it in a similar way to FutureOS, in case of CP/M Plus DISCKIT the Ready signal is used to sense if a disc is inside the drive or not.
http://futureos.de --> Get the revolutionary FutureOS (Recent update: 2018.08.23)
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