The Amiga has a device called a 'trackdisk.device'.
And yet is does not exist anywhere on the Workbench.
And the reason.? I presume is cus it is in ROM.
The 'trackdisk.device' drives the floppy drives. Simple
The hand of the Amiga is your 'trackdisk.device' asking
OK so how does the Amiga MOUNT a device. Let me use
First up , for a disk to be bootable it really needs
The 'startup-sequence' executes s:StartupII.
And 'StartupII' can be loaded with all kinds
My understanding is that the 'Mountlist' items
And so if referred to as being mounted the Amiga
This is where the originating 5.25" drive entry
Jay Miner was very keen that the Amiga be used
Enter the Amiga 1020 5.25" 40 track external drive.
Expanding on those mount options you needed
Also with two drives existent on the A2000
With the later versions of Workbench the concept
With specific PC drives for running CrosssDOS
Unlike trackdisk the PC file uses an mfm.device.
Note the HighCyl=79 reference.
And the mfm.device actually exists on the WB.
The 'DEVS:DOSDrivers' content is mounted as
The A1020 external 5.25" disk drive does not have
That is why a special entry is required for a
Think of HighCyl=39 as a 40 track device.
The A1020 is a 40 track only device.
When Transformer was released it was targeted
Part of the configuration involves setting up
This is Transformer being launched.
It was common to see 5.25" drives and 3.5"
Thing is that most other 5.25" drives came
This is the drive on the Checkmate.
The magic of the 80 track drive is that the Amiga
The drive has the Highest Cylinder as 79.
The PC format option assumes 720K the higher value.
What is amazing is the Amiga does this automatically
The CrossDOS entry for the mfm device uses
That HighCyl of 79 is the 80 track reference.
And yet... AND YET.. my entry doesn't use 79 for
My entry uses 39 or 40 track. WHY OH WHY ??
The drive is set to the 80 track on the switch.
Maybe cus it recognises the lower capacity
I am back to my Unit 1 and Unit 2 conundrum and
I'm going to have my tea.
ScuzzBlog: Diaries February 2025
Entry 6th February 2025: Post 1: Trackdisk - Mounting problems.
Trackdisk - Mounting problems.
I want to discuss a minor issue with mounting drives on the Amiga.
I talk from my own interpretation of matters and come to this blog
page with only my own limited understanding of the Amiga workings.
First up can I say it is quite interesting that although there is
a very detailed Amiga Wiki entry for 'trackdisk.device' at no point
in the endless descriptive text of the entry does it say that the
'trackdisk.device' is actually held in ROM and not mounted from the
Workbench. An obvious point I know, but there are any number of
users struggling with the location of say trackdisk and scsi that
look for a device in the Workbench that they can interrogate.
So what is today's blog about? Basically trying to understand just
how the Amiga distinguishes between a 39 and 79 highest cylinder.
A conundrum that has driven me bonkers this last few days. The
drives I am interested in are the 5.25" drives.
Anyhoo, I thought I would go back to first basics and explain how
I see things. Probably totally wrong , but hey, I'm trying.
Trackdisk - Mounting problems.
If you don't believe me go Google 'trackdisk.device'
and prepare to be astounded and amazed at just what
you can do using AmigaDOS commands to the trackdisk.
as that. And the reason it is in ROM is cus the system
needs a mounted floppy drive to boot the Workbench.
for a disk to be inserted. The clicking you hear is
beating heart of your trackdisk.
Workbench 1.3 as basically the earliest that I kinda
have a basic understanding of.
a 'Startup-Sequence'. This can be found in the 's'
drawer along with 'Startup-Sequence.HD' and
'StartupII'. You may also have 'user-startup'.
of mount files, the content of which is held
in a 'mountlist' in your 'devs' drawer.
only become active when they are mounted from
a statement in the 'startup'.
uses the descriptive in the 'mountlist'.
shows its face as a 'HighCyl=39' device. The
40 track device in question being the Amiga 1020
which was used with the Transformer software.
as an IBM clone and Transformer with the A1020
was first intended to do that. The A1060 was
then released as a more powerful option.
a mount file for a hard drive.
a third drive externally also needed to be
mounted. Note again the ref to A and B which
are MSDOS references.
of the DOSDriver was introduced.
to read MSDOS based disks.
part of the 'startup-sequence'. So if you
have an entry in the drawer for the PC1 etc
you will automatically scan a disk for MSDOS
type status. ie . PC1 notifications on WB screen.
an option to mount 80 track drives.
'trackdisk.device' with a HighCyl=39 status.
for use with the A1020 and was even shipped
with the drive.
the external drives to imitate the A,B,C etc
format of MSDOS based machines.
drives connected for this purpose.
with an 80 track option.
just treats the 5.25" drive as a conventional
3.5" Amiga drive.
The drives do not issue a Unit number that the
Amiga takes any notice of.
the same settings as the 3.5" normal drive
with a HighCyl of 79.
the external 5.25" drive 80 track drive.
MSDOS disks 360K in size. I don't know.
whether I should change it to 79. In this instance
I choose not. The system is working. The drives
are recognising the standard Amiga disks sizes
and reading MSDOS disks. Stuff it. Who cares...
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Last updated 6th February 2025
Chandraise Kingdom
Keep the Faith
scuzzscink 2025