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Tweaks to System Guide

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Wayne Warthen
2025-04-04 09:28:46 -07:00
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@@ -168,14 +168,14 @@ For example, let's say we have a typical system with 512KB of ROM and
512KB of RAM. The following table demonstrates how Bank Ids represent
areas of physical memory.
| Physical Memory | Type | Physical Bank | Bank Id |
|-------------------|------|---------------|-----------|
| 0x000000-0x007FFF | ROM | 0 | 0x00 |
| 0x008000-0x00FFFF | ROM | 1 | 0x01 |
| 0x010000-0x07FFFF | ROM | 2-15 | 0x02-0x0F |
| 0x080000-0x087FFF | RAM | 16 | 0x80 |
| 0x088000-0x08FFFF | RAM | 17 | 0x81 |
| 0x090000-0x0FFFFF | RAM | 18-31 | 0x82-0x8F |
| **Physical Memory** | **Type** | **Physical Bank** | **Bank Id** |
|-----------------------|----------|-------------------|---------------|
| 0x000000-0x007FFF | ROM | 0 | 0x00 |
| 0x008000-0x00FFFF | ROM | 1 | 0x01 |
| 0x010000-0x07FFFF | ROM | 2-15 | 0x02-0x0F |
| 0x080000-0x087FFF | RAM | 16 | 0x80 |
| 0x088000-0x08FFFF | RAM | 17 | 0x81 |
| 0x090000-0x0FFFFF | RAM | 18-31 | 0x82-0x8F |
Note that Bank Id 0x00 is **always** the first bank of ROM and 0x80 is
**always** the first bank of RAM. If there were more banks of physical ROM,
@@ -197,23 +197,23 @@ table describes the way the banks are assigned. The Typical column
shows the specific values that would be assigned for a common system
with 512KB of ROM and 512KB of RAM (nROM=16, nRAM=16).
| Bank Id | Identity | Typical | Purpose |
|-------------------|-----------|---------|------------------------------------------|
| 0x00 |BID_BOOT | 0x00 | Boot Bank (HBIOS image) |
| 0x01 |BID_IMG0 | 0x01 | Boot Loader, Monitor, ROM OSes, ROM Apps |
| 0x02 |BID_IMG1 | 0x02 | ROM Apps |
| 0x03 |BID_IMG2 | 0x03 | \<Reserved\> |
| 0x04 |BID_ROMD0 | 0x04 | First ROM Disk Bank |
| nROM - 1 | | 0x0F | Last ROM Disk Bank |
| 0x80 |BID_BIOS | 0x80 | HBIOS (working copy) |
| 0x81 |BID_RAMD0 | 0x81 | First RAM Disk Bank |
| 0x80 + nRAM - 8 | | 0x88 | Last RAM Disk Bank |
| 0x80 + nRAM - 7 |BID_APP0 | 0x89 | First Application Bank |
| 0x80 + nRAM - 5 | | 0x8B | Last Application Bank |
| 0x80 + nRAM - 4 |BID_BUF | 0x8C | OS Disk Buffers |
| 0x80 + nRAM - 3 |BID_AUX | 0x8D | OS Code Bank |
| 0x80 + nRAM - 2 |BID_USR | 0x8E | User Bank (CP/M TPA) |
| 0x80 + nRAM - 1 |BID_COM | 0x8F | Common Bank |
| **Bank Id** | **Identity** | **Typical** | **Purpose** |
|---------------------|--------------|-------------|--------------------------------------------|
| 0x00 | BID_BOOT | 0x00 | Boot Bank (HBIOS image) |
| 0x01 | BID_IMG0 | 0x01 | Boot Loader, Monitor, ROM OSes, ROM Apps |
| 0x02 | BID_IMG1 | 0x02 | ROM Apps |
| 0x03 | BID_IMG2 | 0x03 | \<Reserved\> |
| 0x04 | BID_ROMD0 | 0x04 | First ROM Disk Bank |
| nROM - 1 | | 0x0F | Last ROM Disk Bank |
| 0x80 | BID_BIOS | 0x80 | HBIOS (working copy) |
| 0x81 | BID_RAMD0 | 0x81 | First RAM Disk Bank |
| 0x80 + nRAM - 8 | | 0x88 | Last RAM Disk Bank |
| 0x80 + nRAM - 7 | BID_APP0 | 0x89 | First Application Bank |
| 0x80 + nRAM - 5 | | 0x8B | Last Application Bank |
| 0x80 + nRAM - 4 | BID_BUF | 0x8C | OS Disk Buffers |
| 0x80 + nRAM - 3 | BID_AUX | 0x8D | OS Code Bank |
| 0x80 + nRAM - 2 | BID_USR | 0x8E | User Bank (CP/M TPA) |
| 0x80 + nRAM - 1 | BID_COM | 0x8F | Common Bank |
In this table, nROM and nRAM refer to the number of corresponding
ROM and RAM banks in the the system.
@@ -292,6 +292,23 @@ hence the name "Common".
# Disk Layout
## Floppy Disk Layout
RomWBVW generally handles floppy disks in the same physical formats
as MS-DOS. However, the filesystem will normally be CP/M. The following
table lists the floppy disk formats used by RomWBW. In all cases,
the sector size is 512 bytes.
| **HBIOS Media ID** | **Capacity** | **Tracks** | **Heads** | **Sectors** |
|--------------------|-------------:|-----------:|----------:|------------:|
| MID_FD720 | 720KB | 80 | 2 | 9 |
| MID_FD144 | 1440KB | 80 | 2 | 18 |
| MID_FD360 | 360KB | 40 | 2 | 9 |
| MID_FD120 | 1200KB | 80 | 2 | 15 |
| MID_FD111 | 1155KB | 77 | 2 | 15 |
## Hard Disk Layout
RomWBW supports the use of PC MBR hard disk partitioning (see
<https://en.wikipedia.org/wiki/Disk_partitioning>). When accessing
a hard disk device, HBIOS will look for a partition with type id 0x2E
@@ -378,7 +395,7 @@ The FAT partition can be initialized using the FAT application from CP/M
using the command `FAT FORMAT n:` where n is the RomWBW disk unit
number containing the FAT partition to be formatted.
## Modern Disk Layout (hd1k)
### Modern Hard Disk Layout (hd1k)
![Modern Disk Layout](Graphics/hd1k)
@@ -389,7 +406,7 @@ The CP/M slices reside entirely within a hard disk partition of type
0x2E. The number of slices is determined by the number of slices that
fit within the partition spaces allocated up to the maximum of 256.
## Classic Disk Layout (hd512)
### Classic Hard Disk Layout (hd512)
![Classic Disk Layout](Graphics/hd512)
@@ -416,20 +433,18 @@ application. The user is responsible for ensuring that the start of the
FAT partition does not overlap with the area they intend to use for
CP/M slices. FDISK80 has a Reserve option to assist with this.
## Mapping to Media ID
### Mapping to Media ID
HBIOS has a definition of "Media ID", which defines the type and physical
properties of disk media provided by an underlying storage device. For a
complete list of Media ID's please see the following section
[Disk Input/Output (DIO)]
complete list of Media ID's please see [Disk Input/Output (DIO)].
There are two important Media ID's relating to Hard Disk Layouts:
| **Media** | **ID** | **Format / Meaning** |
|------------|-------:|-------------------------------------------------------------|
| MID_HD | 4 | Classic Disk Layout (hd512) *--and--* HBIOS Hard Disk Drive |
| MID_HDNEW | 10 | Modern Disk Layout (hd1k) |
| **Media** | **ID** | **Format / Meaning** |
|----------------|-------:|-------------------------------------------------------------|
| MID_HD | 4 | Classic Disk Layout (hd512) *--and--* HBIOS Hard Disk Drive |
| MID_HDNEW | 10 | Modern Disk Layout (hd1k) |
HBIOS typically does not understand the format of data on a device,
instead just treating all hard disks as raw sectors. `MID_HD` is the typical