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Fix hd512 Layout

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- Slice protection changes broke hd512 layout.  Fixed.
- Updated documentation for slice protection changes.
This commit is contained in:
Wayne Warthen
2023-10-07 19:01:36 -07:00
parent 0598d921bc
commit 14cc41c3c4
14 changed files with 73 additions and 48 deletions
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70
Source/Doc/UserGuide.md
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@@ -966,16 +966,24 @@ Drives E: thru L: have been assigned to the IDE0 hard disk device. The
4 entries for IDE0 are referring to 4 slices on that disk. Slices are
discussed later.
The drive letter assignments **do not** change during an OS session
unless you use the `ASSIGN` command yourself to do it. Additionally,
the assignments at boot will stay the same on each boot as long as you
do not make changes to your hardware configuration. Note that the
assignments **are** dependent on the media currently inserted in hard
disk drives. So, notice that if you insert or remove an SD Card or CF
Card, the drive assignments will change. Since drive letter
assignments can change, you must be careful when doing destructive
things like using `CLRDIR` to make sure the drive letter you use is
referring to the desired media.
**WARNING**: Drive letter assignments do **not** ensure that the slice
referenced by the drive letter actually fits on the media you are using.
For example, a typical 64MB CF Card (which is typically a bit smaller
than 64MB) will only fit 7 slices. At startup, you will typically see
8 drive letters assigned to the CF Card. Attempting to access the
last drive letter will result in a "no disk" error from the operating
system.
The drive letter assignments **do not** change during an OS session
unless you use the `ASSIGN` command yourself to do it. Additionally, the
assignments at boot will stay the same on each boot as long as you do
not make changes to your hardware configuration. Note that the
assignments **are** dependent on the media currently inserted in hard
disk drives when the operating system is started. So, notice that if you
insert or remove an SD Card or CF Card, the drive assignments will
change. Since drive letter assignments can change, you must be careful
when doing destructive things like using `CLRDIR` to make sure the drive
letter you use is referring to the desired media.
When performing a ROM boot of an operating system, note that A: will
be your RAM disk and B: will be your ROM disk. When performing a disk
@@ -989,7 +997,8 @@ boot drive.
A typical RomWBW system has 512KB of ROM and 512KB of RAM. Some
portions of each are dedicated to loading and running applications
and operating system. The space left over is available for an
operating system to use as a pseudo-disk device.
operating system to use as a pseudo-disk device (ROM Disk and RAM
Disk).
The RAM disk provides a small CP/M filesystem that you can use for the
temporary storage of files. Unless your system has a battery backed
@@ -1018,13 +1027,13 @@ actual operating system and are not "bootable". However, they are
accessible to any operating system (whether the operating system is
loaded from ROM or a different disk device).
Neither RAM not ROM disks require explicit formatting or initialization.
Neither RAM nor ROM disks require explicit formatting or initialization.
ROM disks are pre-formatted and RAM disks are formatted automatically
with an empty directory when first used.
#### Flash ROM Disks
The limitation of ROM disks being read only can be overcome on some
The limitation of ROM disks being read-only can be overcome on some
platforms with the appropriate selection of Flash ROM chip and
system configuration. In this case the flash-file system can be
enabled which will allow the ROM disk to be read and written to.
@@ -1208,7 +1217,7 @@ available storage devices. The allocation will depend on the number of
mass storage devices available at boot. For example, if you have
only one hard disk type media, you will see that 8 drive letters are
assigned to the first 8 slices of that media. If you have two large
storage devices, you will see that each device is allocated four drive
storage devices, you will see that each device is allocated 4 drive
letters.
Referring to slices within a storage device is done by appending a :
@@ -1223,14 +1232,14 @@ slice of IDE0, you would type "IDE0:3". Here are some examples:
| `IDE0:` | First slice of disk in IDE0 |
| `IDE0:3` | Fourth slice of disk in IDE0 |
So, if you wanted to use drive letter L: to refer to the fourth slice
of IDE0, you could use the command `ASSIGN L:=IDE0:3`. There are a
couple of rules to be aware of when assigning drive letters. First,
you may only refer to a specific device/slice with one drive letter at a time.
Said another way, you cannot have multiple drive letters referring
to a the same device/slice at the same time. Second, there must always
be a drive assigned to A:. Any attempt to violate these rules will
be blocked by the `ASSIGN` command.
So, if you wanted to use drive letter L: to refer to the fourth slice of
IDE0, you could use the command `ASSIGN L:=IDE0:3`. There are a couple
of rules to be aware of when assigning drive letters. First, you may
only refer to a specific device/slice with one drive letter at a time.
Said another way, you cannot have multiple drive letters referring to a
the same device/slice at the same time. Second, there must always be a
drive assigned to A:. Any attempt to violate these rules will be blocked
by the `ASSIGN` command.
In case this wasn't already clear, you **cannot** refer directly
to slices using CP/M. CP/M only understands drive letters, so
@@ -1259,6 +1268,11 @@ absolutely sure you know what media and slice are assigned to that
drive letter before using `CLRDIR` because CLRDIR will wipe out any
pre-existing contents of the slice.
**WARNING**: The `CLRDIR` application does not appear to check for
disk errors when it runs. If you attempt to run `CLRDIR` on a drive
that is mapped to a slice that does not actually fit on the physical
disk, it may behave erratically.
Here is an example of using `CLRDIR`. In this example, the `ASSIGN`
command is used to show the current drive letter assignments. Then
the `CLRDIR` command is used to initialize the directory of drive 'G'
@@ -1408,9 +1422,11 @@ was 512, it would indicate a legacy (hd512) disk layout.
Although RomWBW can support many CP/M filesystem slices on a single
hard disk, you are still constrained by the physical capacity of the
actual hard disk. In most scenarios, RomWBW does not prevent you
from attempting to use more slices than will fit on your hard disk
device. If you attempt to do so, disk I/O errors will be reported.
actual hard disk. RomWBW does not prevent you from assigning slices
to drive letters even if the location of the slice does not fit on the
physical disk. Any attempt to access a drive letter mapped to a slice
that does not fit will result in an error such as "no disk" from the
operating system.
The exact number of CP/M filesystem slices that will fit on your
specific physical hard disk can be determined as follows:
@@ -1590,8 +1606,8 @@ but based on the idea that a 1GB CF or SD Card is easy and cheap to
acquire. It is fine if your hard disk is smaller than 1GB. It just
means that it will not be possible to use the pre-allocated FAT
filesystem partition and any CP/M filesystem slices that don't fit. You
will get I/O errors if you attempt to access an area beyond the end of
the physical hard disk.
will get "no disk" errors if you attempt to access a slice past the
end of the physical hard disk.
**WARNING**:Your hard disk may be too small to contain the full 64
CP/M filesystem slices. The true number of CP/M filesystem slices that