[Coco] Strange.... two 40 track disks on one 80 track disk?

[Tim Fadden]

Fedor,

I do have a 80trk 5-1/2 inch drive in one coco3 system if you would like 
me to give it a shot.

Tim Fadden

Fedor Steeman wrote:

> Hi all,

>

> Thanks for all the responses.

>

> I am quite sure these disks are single-sided and that they came from a setup

> that could use and access 80 track disks. The collection of stuff (including

> the diskettes) I inherited is quite extensive and were used by a highly

> skilled CoCo user. There are drives that are cleared marked as switchable to

> 80 tracks, there are diskettes clearly marked as being 80 tracks. Heck,

> there are even disk controllers with a 40/80 tracks switch (?). I tried

> those but that did not work either.

>

> I am quite sure there was some trick applied when he backed up the diskettes

> two at a time, but I would not know what. As suggested, I will try looking

> through the stuff to see if there was any hardware or software involved. I

> will also think about all the interesting suggestions you guys made so far.

>

> Most of the diskettes are RSDOS BTW.

>

> /Fedor

>

> 2009/11/1 Arthur Flexser <flexser at fiu.edu>

>

>   

>> Of course, if his drives are single-sided, no amount of poking will let him

>> access the back!

>>

>> Art

>> On Sat, Oct 31, 2009 at 8:25 PM, Christopher Hawks <chawks at dls.net> wrote:

>>

>>     

>>> Fedor Steeman said the following on 10/31/2009 03:50 PM:

>>>

>>> Hi,

>>>       

>>>> Some time ago I acquired this huge collection of diskettes that were

>>>>         

>> part

>>     

>>>> of

>>>> a user group's CoCo software library. A lot of these are backups of

>>>> backups

>>>> so there is bound to be a lot of stuff I will be able to recover.

>>>>

>>>> There are a large number of diskettes that seem to contain a backup of

>>>>         

>> two

>>     

>>>> 40 tracks diskettes on one side of an assumed 80 track diskette.

>>>>

>>>> However, I can only access the first diskette of each of these backup

>>>> floppies. I know because some of them have their contents listed on the

>>>> envelope (or whatever you called the paper bag the diskette is in).

>>>>

>>>> I have a drive that can be switched from 80 to 40 tracks but that made

>>>>         

>> no

>>     

>>>> difference.

>>>>

>>>> Is there some way in HDB DOS that I am using (or RSDOS for that matter)

>>>> that

>>>> would enable access to the other 40 tracks and thus the other diskette

>>>> backup?

>>>>

>>>>         

>>> Fedor:

>>>

>>>        It may be that the other tracks are on the other side of the disk

>>> (not as in a flippy).

>>>

>>>        On a Coco 3 (or a 1 or 2 in ram) with DECB 2.1 (1.1), POKE &HD89F,

>>> &H40 will make drive 2 the backside of drive 0. Likewise POKE &HD8A0,&H41

>>> will make drive 3 the back of drive 1. There a 4 memory locations that

>>>       

>> are

>>     

>>> the drive mask (&HD89D - &HD8A0) the relevant bits are:

>>> bit 0 - drive select 0 (&H01)

>>> bit 1 - drive select 1 (&H02)

>>> bit 2 - drive select 2 (&H04)

>>> bit 7 - side select    (&H40)

>>>

>>>        These can be manipulated to access any side of any (physical)

>>>       

>> drive

>>     

>>> as any drive number.

>>>

>>> --

>>> Christopher R. Hawks

>>> HAWKSoft

>>> ---------------------------------------------------------

>>> Never meddle in the affairs of NT. It is slow to boot and quick to crash.

>>>        -- Stephen Harris

>>>

>>>

>>> --

>>> Coco mailing list

>>> Coco at maltedmedia.com

>>> http://five.pairlist.net/mailman/listinfo/coco

>>>

>>>       

>> --

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>>

>>     

>

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