[N8VEM: 17047] Different sizes of C: & D: drives

[p***@public.gmane.org]

Gents,

I just completed my mini PPIDE, made in "flying-wires" style, and it even
works :). One thing which bugs me out is why my C: and D: drives on the IDE
disk are not of the same size:

B0>stat
A: R/W, Space: 408k
B: R/W, Space: 72k
C: R/W, Space: 8160k
D: R/W, Space: 7600k

I'm using N8VEM SBC V2, RomWBW v2.5.1 (N8VEM_ppide.rom).
Any ideas about this will be appreciated.

Regards,
picmaster

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[p***@public.gmane.org]

An interesting observation - "erasing" the drive with PPIDETST.COM fixed
the issue. Now both logical drives are 8176K big.

Regards,
picmaster

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[Wayne Warthen]

Yes, it is necessary to format the drives before using them. You can use
CLRDIR on individual drive letters or use MULTIFMT to format a bunch of
"slices" at once.

--Wayne

Post by p***@public.gmane.org
An interesting observation - "erasing" the drive with PPIDETST.COM fixed
the issue. Now both logical drives are 8176K big.
Regards,
picmaster
-------------------------------------
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[p***@public.gmane.org]

Actually I did "ERA <DRIVE>:*.*" on both drives before observing this, but
looks like the drives want to be even "cleaner" :D. I'll know for the next
time.

-------------------------------------

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[Wayne Warthen]

That is correct. The ERA command is only appropriate for deleting files
from a drive. Prior to using a drive in the first place, it must be
formatted. Floppy disks can be formatted using FDTST. Hard disks
(including IDE, CF, and SD Cards) can be formatted with CLRDIR or MULTIFMT.

--Wayne

Post by p***@public.gmane.org
Actually I did "ERA <DRIVE>:*.*" on both drives before observing this, but
looks like the drives want to be even "cleaner" :D. I'll know for the next
time.
-------------------------------------
Ðàçáðà ëè çà çèìíèòå èçêóøåíèÿ íà ÑóïåðÕîñòèíã.ÁÃ?
Âçåìè õîñòèíã ïëàí ñúñ 75% îòñòúïêà.
http://superhosting.bg/8years/?utm_source=Mail.BG&utm_medium=FooterLink&utm_content=FooterLink102&utm_campaign=Winter-2013

[Max Scane]

Also, the ERA command deletes directory entries for the current user area
only.

For a new disk the directory area needs to be filled with sectors
containing 0xE5.

This was the standard for blank IBM floppy disks.

Simply doing an ERA *.* doesn't clear out invalid directory data and
entries in other user areas. You need to "format" the directory area before
using the disk.

I also read somewhere that the time it takes to login a disk can be
impacted if the directory is not correctly initialized as CP/M looks for a
blank sector in the directory to indicate the high water mark for directory
space.

CLRDIR utilises the BIOS disk definition of the drive to work out the
location and size of the directory area so it should work with any size
CP/M disk.

Regards,

Max

Post by Wayne Warthen
That is correct. The ERA command is only appropriate for deleting files
from a drive. Prior to using a drive in the first place, it must be
formatted. Floppy disks can be formatted using FDTST. Hard disks
(including IDE, CF, and SD Cards) can be formatted with CLRDIR or MULTIFMT.
--Wayne

Post by p***@public.gmane.org
Actually I did "ERA <DRIVE>:*.*" on both drives before observing this, but
looks like the drives want to be even "cleaner" :D. I'll know for the next
time.
-------------------------------------
Ðàçáðà ëè çà çèìíèòå èçêóøåíèÿ íà ÑóïåðÕîñòèíã.ÁÃ?
Âçåìè õîñòèíã ïëàí ñúñ 75% îòñòúïêà.
http://superhosting.bg/8years/?utm_source=Mail.BG&
utm_medium=FooterLink&utm_content=FooterLink102&utm_campaign=Winter-2013
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[p***@public.gmane.org]

Thanks for the explanations. On the bright side, it still amazes me that the
CP/M filesystem design and implementation is obviously robust enough to handle
even such boundary cases.

On the performance side, I was able to "measure" data transfer speed of about
57 KB/s on the PPIDE with my 320GB test disk (Seagate ST3320620A from an old
file server). I know that this speed is not a surprise as we use PIO transfers,
but can anyone of you share what's his transfer speed with the SD-card? My
personal expectation is that the SD interface is bit-banged, and it should be
slower in order of magnitude compared to the PPIDE.

One last thing - it looks to me that it's safe to turn-off the SBC at anytime
as long as there are no PPIDE disk writes. Is it correct?

Regards,
picmaster

-------------------------------------
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[Max Scane]

Yes, the SD interface is slower as it has to be "bit banged" (data and
signalling) whereas the IDE bus is parallel and only the signalling is bit
banged.

I look at the SD card as a "floppy replacement".. and the IDE as a disk
replacement.

You are safe to switch off the power as long as there no writes taking
place.

Max

Post by p***@public.gmane.org
Thanks for the explanations. On the bright side, it still amazes me that the
CP/M filesystem design and implementation is obviously robust enough to handle
even such boundary cases.
On the performance side, I was able to "measure" data transfer speed of about
57 KB/s on the PPIDE with my 320GB test disk (Seagate ST3320620A from an old
file server). I know that this speed is not a surprise as we use PIO transfers,
but can anyone of you share what's his transfer speed with the SD-card? My
personal expectation is that the SD interface is bit-banged, and it should be
slower in order of magnitude compared to the PPIDE.
One last thing - it looks to me that it's safe to turn-off the SBC at anytime
as long as there are no PPIDE disk writes. Is it correct?
Regards,
picmaster
-------------------------------------
Mail.BG: Áåçïëàòåí e-mail àäðåñ. Íàé-äîáðèòå õàðàêòåðèñòèêè íà áúëãàðñêèÿ
ïàçàð - 20 GB ïîùåíñêà êóòèÿ, 1 GB ïðèêðåïåí ôàéë, áåçïëàòåí POP3, ìîáèëíà
âåðñèÿ, SMS èçâåñòÿâàíå è äðóãè. http://mail.bg
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