Speed timings for emulated hard disks

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grommit2007
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Speed timings for emulated hard disks

Post by grommit2007 » Sun 28 Apr, 2019 4:15 am

Would it be possible one day to implement a speed timing feature for the emulated hard disks similar to the speed selection for CD-ROM drives and the timings for video cards?

For example, this page on CNET shows the rotational speed, seek time and data transfer rate (and other useful information for implementing speed timings) for a Western Digital AC33100 hard disk- (this is just an example of information that a user could enter into the HDD file creation dialog box)

https://www.cnet.com/products/wd-caviar ... ide-ata-2/

Also, how much work would be required to implement hard disk timings?

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CryptidWorks
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Re: Speed timings for emulated hard disks

Post by CryptidWorks » Sun 28 Apr, 2019 5:03 am

Is that really a level accuracy we need?

Most people aren't going to choose to emulate a terrible and slow old HDD over the modern 7200RPM unit or even SSD the HDD image is saved to.

grommit2007
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Re: Speed timings for emulated hard disks

Post by grommit2007 » Sun 28 Apr, 2019 5:37 pm

CryptidWorks wrote:
Sun 28 Apr, 2019 5:03 am
Is that really a level accuracy we need?

Most people aren't going to choose to emulate a terrible and slow old HDD over the modern 7200RPM unit or even SSD the HDD image is saved to.
It will help with historical accuracy, as PCem has this already with CPU speeds, CD-ROM speeds and timings for video cards, so I figured, why not suggest HDD timing?

Also, an option to use the previous implementation (possibly by having default options for HDD timing parameters) should be included if this feature is ever implemented.

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CryptidWorks
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Re: Speed timings for emulated hard disks

Post by CryptidWorks » Sun 28 Apr, 2019 8:55 pm

grommit2007 wrote:
Sun 28 Apr, 2019 5:37 pm
CryptidWorks wrote:
Sun 28 Apr, 2019 5:03 am
Is that really a level accuracy we need?

Most people aren't going to choose to emulate a terrible and slow old HDD over the modern 7200RPM unit or even SSD the HDD image is saved to.
It will help with historical accuracy, as PCem has this already with CPU speeds, CD-ROM speeds and timings for video cards, so I figured, why not suggest HDD timing?

Also, an option to use the previous implementation (possibly by having default options for HDD timing parameters) should be included if this feature is ever implemented.
A lot of that is necessary because some games and programs just do not work right on modern CPUs/GPUs several magnitudes faster than what they were designed for. Blood II is a stellar example because it absolutely crawls without a mod that fools the game into thinking it's running an old Glide/Voodoo card when run on modern hardware.

Simulating HDD timing/speed really isn't unless there's some obscure use-case I'm not aware of.

EluanCM
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Re: Speed timings for emulated hard disks

Post by EluanCM » Sun 28 Apr, 2019 9:10 pm

PCem is not just a wrapper or virtualization software, so accurate timings make total sense. Also, inaccurate disc access times and/or behavior are known to cause problems in various platforms, for example see "5.0-2431 - DVD Timing Accuracy Upgrades" in this report: https://dolphin-emu.org/blog/2017/03/01 ... uary-2017/

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leilei
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Re: Speed timings for emulated hard disks

Post by leilei » Sun 28 Apr, 2019 11:20 pm

I certainly wouldn't oppose to an option to limit hard drive access speed. I already sort of did a slow down the floppy controller in my noise patch.... Heck, for even more accuracy, one could go as far as to add support for a hard drive database file to match names, speeds, and dimensions (......and maybe samples) with

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omarsis81
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Re: Speed timings for emulated hard disks

Post by omarsis81 » Mon 29 Apr, 2019 1:32 am

leilei wrote:
Sun 28 Apr, 2019 11:20 pm
Heck, for even more accuracy, one could go as far as to add support for a hard drive database file to match names, speeds, and dimensions (......and maybe samples) with
I support your idea, in fact I suggested something similar here http://pcem-emulator.co.uk/phpBB3/viewt ... 4855#p4855

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KingDaveRa
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Re: Speed timings for emulated hard disks

Post by KingDaveRa » Sat 11 May, 2019 9:25 pm

I rather like the idea that when creating an HD, it could be possible to select from a list of makes and models, much like you can with other hardware. Granted, it'd be little more than a cosmetic thing right now, but it'd make sizing drives easier, and not coming up with wacky geometry some OSes might not like.

When sizing disks, I very often go look on eBay for a drive of the rough size I want, and take the geometry from the pictures on a listing. :)

Zup
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Re: Speed timings for emulated hard disks

Post by Zup » Sun 12 May, 2019 7:29 am

KingDaveRa wrote:
Sat 11 May, 2019 9:25 pm
I rather like the idea that when creating an HD, it could be possible to select from a list of makes and models, much like you can with other hardware. Granted, it'd be little more than a cosmetic thing right now, but it'd make sizing drives easier, and not coming up with wacky geometry some OSes might not like.

When sizing disks, I very often go look on eBay for a drive of the rough size I want, and take the geometry from the pictures on a listing. :)
Maybe it would be easier to make a list of interfaces and "typical" timings. Most MFM, RLL and ESDI disks usually had the same performance at consumer levels (I mean, most RLL disks shared about the same performance). Maybe SCSI and PATA disks should have subcategories (based on RPM? or slow-medium-fast like bus timings?). Having a complete database of timings of every disks manufactured would be too much work.

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