CPU280 3.5" 1760K format support

HxC Floppy emulator support for all others computers...
Jeff
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Re: CPU280 3.5" 1760K format support

Post by Jeff »

Thanks. The .raw and the .HFE files appear to be perfectly fine.

for the format you may need a faster sdcard.

sijnstra
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Re: CPU280 3.5" 1760K format support

Post by sijnstra »

Thanks Jeff!

Speed of the card is rated up to 48MB/s read, and based on what I can find is rated up to 16MB/s sequential write (no official information available, only tested specs).

What kind of speed would avoid these issues so I can try something more likey?

Thanks,
Shawn

Jeff
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Re: CPU280 3.5" 1760K format support

Post by Jeff »

Which sdcard model have you ?

sijnstra
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Re: CPU280 3.5" 1760K format support

Post by sijnstra »

Hi

It's a Toshiba 16GB SDHC UHS-I speed class 1, rated at 48MB/s read.

I put it through media tester (Quick Test), and the read speed, write speed and capacity were all correct with no read or write errors so unlikely fake.

Averge write speed: 13,730,673 Bytes/sec
Averge read speed: 44,351,194 Bytes/sec

Jeff
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Re: CPU280 3.5" 1760K format support

Post by Jeff »

class 1 ?

sijnstra
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Re: CPU280 3.5" 1760K format support

Post by sijnstra »

As in UHS-1:

"UHS-1" or more accurately "UHS-I" stands for "Ultra High Speed" - 1 and is a speed class for SDHC and SXDC memory cards.

UHS-I has a bus interface speed of up to 104 MB/s.

Thanks,
Shawn

Jeff
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Re: CPU280 3.5" 1760K format support

Post by Jeff »

sijnstra wrote:
Tue Oct 13, 2020 12:40 pm
As in UHS-1:

"UHS-1" or more accurately "UHS-I" stands for "Ultra High Speed" - 1 and is a speed class for SDHC and SXDC memory cards.

UHS-I has a bus interface speed of up to 104 MB/s.

Thanks,
Shawn
ok. Unfortunately these speed are only possible with a big write buffer. The emulator is only writing some few KB once.
Smaller/older sdcard are probably better with small writes. The 16GB Class 10 Sandisk Extreme series are quite good for example.

sijnstra
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Re: CPU280 3.5" 1760K format support

Post by sijnstra »

Interesting! So the SD Card may be too fast? I'll shop around and see what I can find. Thank you!

Jeff
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Re: CPU280 3.5" 1760K format support

Post by Jeff »

sijnstra wrote:
Wed Oct 14, 2020 10:44 am
Interesting! So the SD Card may be too fast? I'll shop around and see what I can find. Thank you!
This more complex than this : Technically the sdcard should have a good cache algorithm :)
The issue is the small write latency. The floppy doesn't have write latency, a flash memory have a latency. The SDCard generally have the necessary cache algorithm to reduce it. But this is now done for big files (pictures/movies), not for just some sectors.

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Re: CPU280 3.5" 1760K format support

Post by Jeff »

To illustrate this :
W7Rzk.jpg
W7Rzk.jpg (95.3 KiB) Viewed 213 times

sijnstra
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Re: CPU280 3.5" 1760K format support

Post by sijnstra »

Perfect! Thank you. Interesting to know how much variance there is between cards. I bought a Class 4 (much slower) SanDisk (changed brands as well), and now I can perfectly format as well. I will experiment with other SD cards to see what works best.

I very much appreciate your time and patience.

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