> > On Wednesday 16 May 2001 14:05, Sellam Ismail hit his keyboard with a hammer
> > and this was the result:
> > > You're assuming he won't do something clever such as add an electronic
> > > counter so he can fast forward to just before the desired block?
> > I was planing on this. I will have a block of sound at the start of the tape,
> > that will indicate what is 1 second for this recorder. This will calibrate it
> > to be able to seek the second of the tape it wants. It will then read in the
> > FAT and seek the file directly.
> Remember that the tape speed is not constant (assuming constant speed
> motors) in fast forward or rewind mode. Because the diameter of the
> spools changes as tape winds on/off them.
> Some people have tried clever tricks where they put some kind of
> tachometer (slotted disk + optoswitch, or tachogenerator) on each spool.
> By measuring the speed of both of them, they can work out roughly where
> they are on the tape, and also, by counting _both_ sets of tacho pulses
> it's possible to do a reasonably accurate seek. It's still generally
> necessary to format the tape (as in writing down block headers and dummy
> data) when you first use a new blank tape, and then seeking by going to
> approximately the right place and then reading a few blocks to get to the
> right one.
Also this would almost need a seperate CPU for tape control.
Otherwise the Computer would be more like a ZX81 - with all
the fine tuning needed for timing your programm code with the
tape hardware.
Although it sounds like a fun project, I would skip this and
go for a simple solution.
Gruss
H.
--
VCF Europa 3.0 am 27./28. April 2002 in Muenchen
http://www.vcfe.org/
Received on Thu May 17 2001 - 04:51:18 BST