Fixing 8050 Disk Drive

[Blacklord]

Original post by Panther

I think my 8050 drive may be fecked

When I boot up my 8096-sk and it's connected to the drive, the drive lights flash as they should, center light goes green, when I use the command 'Print DS$' and I get the message 73,cbm dos v2.5 8050,00,00

If I then use the command 'Header"Game",d1' with a disk in drive 1 the drive spins for a while then makes a strange noise, the drive head appears to move back towards the motor and then reaches it's limit (if that makes sense) causing the noise as the motor tries to move it back further. I then get the message '? bad disk' If I then retype 'Print DS$' I get the following message '21,read error,39,00' (this happens on both drive 0 & 1)

I know that error 21 can be due to misalignment of the read/write heads, which I think is causing the problem, as the head seems to start in the middle of the disk and then move out until it reaches it outer limit. Is there an easy way to realign the heads, or could this be due to some other problem ?

I'd love to get the drive working properly, it was working OK when I first got it, but not used it for a while.

Any help appreciated as always.

[Blacklord]

Original post by Panther

I found this on Wikipedia from the 1541 drive, which sounds just like what my 8050 is doing !!

"The main cause of the problem was that the disk drive itself did not feature any means of detecting when the read/write head had reached track zero. Accordingly, when a disk was formatted or a disk error occurred, the unit would physically drive the head 40 tracks to track zero (although the 1541 DOS only used 35 tracks, the drive itself was a 40 track unit). Once track zero was reached, the head would be physically rammed against a solid stop. This ramming gave the characteristic 'machine gun' noise and would, sooner or later, throw the head out of alignment."

[Blacklord]

Original post by pet1978

The command 'Header"Game",d1'  will do a quick reformat of an already formatted disk. You must specify a new disk ID to have the drive do a complete low level format.

Try 'Header"Game",d1,iG1'

Dave

[Blacklord]

Original post by Panther

I can use the 'Header"diskname",dx' command OK, it doesn't work, get the machine gun sound as above, but when I try 'Header"diskname",dx,ixx' I get Syntax Error ?

Well confused

Certainly sounds like alignment problem, but can't find any info on how to fix this !

[Blacklord]

Original post by pet1978

OK, let me try again.

All the sounds you describe are normal for trying to read an unformatted disk. The disk drive itself sounds like it is working properly.

When you give the command 'header"diskname",d0' the drive will first try and read the BAM (Block Availability Map) on track 39, sector 0. On an unformatted disk it will search around a bit to try and figure out what track the head is over. Not finding any track to read it will give up and go to track one by moving the head the maximum number of tracks (77). There is no switch at track zero so you get the machine gun sound of the head bumping on the stop. Normally around 38 "bangs". The it will try again on track 39. Not finding any sector to read it will give up with a read error on track 39 sector 00.

So we need to use the form of the header command that specifies an ID. If you get a syntax error that just means you have typed something wrong. All versions of Basic 4 have this form of the command. I may have confused things with poor capitalization. A capital in the ID won't work. An f also doesn't work.

With a blank disk in drive 0, type:

header "game",d0,i22

Basic will respond with "are you sure?"

Dave

[Blacklord]

Original post by Panther

Dave,

MANY, MANY, MANY thanks, you are an absolute star !!!!!!

It's works a treat, managed to format (or is it initialise) a disk in both drives, typed in the command diRd0 and got the response

0 "game          " 22 2c
2052 blocks free

Which I'm presuming it should.

So happy to be able to use the drive, just got to try and get some software onto the PET/drive !

Stu.