fabio santos <[EMAIL PROTECTED]> writes:
> in 1990,here in BRAZIL,two guys from SAO PAULO,SP made a program called
> FASTCOPY.This program could copy a 360k or 720k floppy disks faster than
> a PC...(In that time the standart was the AT 286)..Believe me,i tested
> this program and it really worked!!!!
It's probably formatting and writing at the same time ?
The fastest time to read or write a 720k floppy disks is:
80 tracks * 2 sides = 160 rotations / 300rpm = 32 seconds if you don't
have
to adjust the head at any time and if you read all 9 sectors in 1 rotation.
Most MSX floppies use '1-6-2-7-3-8-4-9-5' interleaving. This means that if
you ask the DISKBIOS for sector 0-8 then it will need at least 2 rotations
to read them. Then it takes at least 64 seconds to read a disk on MSX.
If you *KNOW* the interleaving then most newer MSX disk-bioses can actually
read the disk in 32 seconds if your program doesn't have to move each
sector.
This depends greatly on the size of the gap between each sector and on how
well the diskbios was written.
In that case you should read 1 sector at a time and in the order of the
interleaving.
I rewrote/optimized the SVI-738 diskbios. After that it was faster to use
PC
formatted disks than MSX disks. Turbo R formatted disks are very slow
though because the gap between the sectors are 'too' short. (The TBR use
interleaving '1-2-3-4-5-6-7-8-9')
The MSX can read 720k disks just as fast as any PC. It *HAS* to! or it
would
loose the data. The problem on the MSX is that you also need CPU power
enough to move/use the data and to go through the DOS/BIOS code.
Newer PC's use faster drives which moves the head faster than the MSX. If
you use a PC diskdrive on a MSX and use a slow stepspeed then the drive
will
make much more noise when stepping while if the FDC step faster then there
will much less noise.
The 3.5MHz MSX is too slow to read 1.44MB disks when using FDC's like the
1793/2793 and the PC compatible FDCs which require the CPU to 'poll' for
each databyte. A 720K disk returns 31250 bytes/sec to the head (only 23040
bytes are real sector data). A 1.44MB disk returns 62500 B/s.
A good IDE or SCSI interface can return 120.000 B/s on a 3.5MHz MSX so it's
really a matter of how intelligent the Drive/interface are.
Bye,
Henrik Gilvad <[EMAIL PROTECTED]>
