28 Apr
2013
28 Apr
'13
11:55 a.m.
On 04/28/2013 05:51 AM, shadoooo wrote:
Hello.
I have an old VAX 730 that needs to be restored, and temporaneously is
stored,
because of lack of space to disassemble and repair the machine.
With the machine it came a box of old cassettes, that I would try to read.
Furthermore, I'm working on disassembling the code of a TU58 rom,
because I would try to hack the firmware to provide the ability to format
an empty DC100 cassette.
Important 730 note is that those are the microcode boot tapes. BEFORE you
put on in the drive on that machine inspect the drive roller as it is
more than
likely failed and turned to a goo. Without the boot tapes that machine
is not very useful. However the drive can be replace with an emulator
as the interface is serial RS423.
Good luck on a formatter. The drive has no physical EOT/BOT sense that
alone
makes formatting near impossible. The system senses EOT/BOT by reading
the tape, if those marks are missing or the head is dirty, the usual
result is
you run off then end of the tape and have to open it up and thread
it. If
the format is missing it will without fail run off the end.
So to format media you will have to modify the physical drive to ad
EOT/BOT sense
and the controller to likely add IO, EPROM and possibly more ram to do
that. You
will also need to bit by bit read the tape for the actual base format.
It is far easier to duplicate the communication protocol and create a
controller
that uses Flash, Ram with battery backup, SD, or CF as the storage media
that acts like a TU58. Also the result would not have the physical
rewind delay
and would be effectively faster. The other pain you will avoid is that
tape availability
is going away and the problem of media failure over time.
Allison