mirror of
https://github.com/alfishe/amiga-bootcamp.git
synced 2026-06-13 00:26:28 +00:00
b915524667
- Add comprehensive cdfs.md covering ISO 9660, UDF, handlers, and hardware. - Update relevant section indexes (07_dos, 10_devices, 02_boot_sequence) and root README. - Expand scsi.md to link to the new CDFS coverage.
292 lines
11 KiB
Markdown
292 lines
11 KiB
Markdown
[← Home](../README.md) · [Devices](README.md)
|
||
|
||
# scsi.device — Hard Disk, CD-ROM, and Mass Storage I/O
|
||
|
||
## Overview
|
||
|
||
SCSI and IDE hard disks on the Amiga are accessed through `scsi.device` or compatible device drivers. The API is consistent across implementations — the same IORequest structure and commands work regardless of whether the underlying hardware is Commodore's native Gayle IDE, a Zorro SCSI card, or an accelerator-integrated controller.
|
||
|
||
---
|
||
|
||
## Disk Interfaces by Amiga Model
|
||
|
||
| Model | Interface | Controller | Device Name | Bandwidth Limit |
|
||
|---|---|---|---|---|
|
||
| A500 | None (stock) | — | — | Requires external SCSI card |
|
||
| A500+ | None (stock) | — | — | Requires external SCSI card |
|
||
| A600 | IDE (44-pin) | **Gayle** | `scsi.device` | ~1.5 MB/s (PIO, 16-bit CIA) |
|
||
| A1000 | None (stock) | — | — | Requires SCSI sidecar |
|
||
| A1200 | IDE (44-pin) | **Gayle** | `scsi.device` | ~1.5 MB/s (PIO) |
|
||
| A2000 | None (stock) | — | — | Zorro II SCSI cards |
|
||
| A3000 | SCSI (50-pin) | **WD33C93** | `scsi.device` | ~3 MB/s (DMA) |
|
||
| A4000 | IDE (40-pin) | **A4000 IDE** | `scsi.device` | ~2 MB/s (PIO) |
|
||
| A4000T | SCSI (50-pin) + IDE | **NCR 53C710** + IDE | `2nd.scsi.device` / `scsi.device` | ~10 MB/s (SCSI DMA) |
|
||
| CD32 | IDE (internal CD) | **Akiko** | `scsi.device` | ~1.5 MB/s |
|
||
| CDTV | SCSI (internal CD) | **DMAC + WD33C93** | `scsi.device` | ~150 KB/s (1× CD) |
|
||
|
||
### Why Native Bandwidth Is Limited
|
||
|
||
The A600/A1200 **Gayle** IDE interface is the most common and the most constrained:
|
||
|
||
```mermaid
|
||
flowchart LR
|
||
CPU["68020/68030<br/>(fast bus)"] -->|"PIO transfer<br/>WORD at a time"| GAYLE["Gayle IDE<br/>(no DMA!)"]
|
||
GAYLE -->|"16-bit ATA"| DRIVE["IDE Drive"]
|
||
|
||
style GAYLE fill:#ffcdd2,stroke:#c62828,color:#333
|
||
```
|
||
|
||
| Bottleneck | Explanation |
|
||
|---|---|
|
||
| **No DMA** | Gayle has no DMA engine — every word must be moved by the CPU (`MOVE.W` loop) |
|
||
| **16-bit bus** | Gayle connects via 16-bit data path even on 32-bit CPUs |
|
||
| **PIO mode 0** | Stock Gayle supports only PIO mode 0 (~3.3 MB/s theoretical, ~1.5 MB/s actual) |
|
||
| **CIA timing** | CIA chip access introduces wait states |
|
||
| **CPU overhead** | 100% CPU utilization during transfers — no multitasking during disk I/O |
|
||
|
||
### Community Solutions — Fast IDE
|
||
|
||
| Solution | Method | Improvement |
|
||
|---|---|---|
|
||
| **FastATA** (E-Matrix/Elbox) | Zorro SCSI/IDE card with DMA | Up to ~10 MB/s, frees CPU |
|
||
| **Buddha/Catweasel** | Clock port / Zorro IDE with optimized driver | ~2–3 MB/s, multiple IDE channels |
|
||
| **Blizzard SCSI** | Accelerator-integrated SCSI | Up to ~5 MB/s with DMA |
|
||
| **GVP Series II** | Zorro II SCSI with custom DMA ASIC | ~3 MB/s, DMA frees CPU |
|
||
| **A4091** | Zorro III SCSI (NCR 53C710) | **~10 MB/s** — fastest stock Amiga SCSI |
|
||
| **CF adapters** | CompactFlash in IDE socket | Same speed, but no mechanical seek latency |
|
||
| **SD/microSD** | Adapter on clock port | Varies, typically slow but no noise |
|
||
|
||
---
|
||
|
||
## Native vs. Vendor Drivers — Software Differences
|
||
|
||
All drivers expose the same `CMD_READ`/`CMD_WRITE`/`HD_SCSICMD` API, but internal differences matter:
|
||
|
||
| Aspect | Commodore `scsi.device` | Vendor Drivers (GVP, A4091, etc.) |
|
||
|---|---|---|
|
||
| **Source** | Commodore ROM or Devs: | Third-party (ships with hardware) |
|
||
| **DMA support** | None (Gayle PIO) | Often DMA-capable |
|
||
| **Interrupt handling** | Level 2 interrupt (CIA) | Card-specific interrupt level |
|
||
| **TD64 / NSD** | Added via patches | Often built-in from factory |
|
||
| **Multi-LUN** | Usually ignored | Proper LUN scanning on SCSI |
|
||
| **Disconnect/reselect** | Not supported (Gayle) | SCSI disconnect on good controllers |
|
||
| **Tagged queuing** | No | Some advanced SCSI controllers |
|
||
| **CD-ROM support** | Basic (atapi.device) | Full ATAPI/SCSI CD support |
|
||
| **Removable media** | Basic change detection | Proper unit attention handling |
|
||
|
||
> [!IMPORTANT]
|
||
> When writing software that accesses disks, **always use the device name from the mountlist** — don't hardcode `scsi.device`. Different systems use different device names for the same physical drive.
|
||
|
||
---
|
||
|
||
## Opening
|
||
|
||
```c
|
||
struct MsgPort *diskPort = CreateMsgPort();
|
||
struct IOStdReq *diskReq = (struct IOStdReq *)
|
||
CreateIORequest(diskPort, sizeof(struct IOStdReq));
|
||
|
||
/* Unit 0 = first device on the bus (master/ID 0): */
|
||
if (OpenDevice("scsi.device", 0, (struct IORequest *)diskReq, 0))
|
||
{
|
||
Printf("Cannot open scsi.device unit 0\n");
|
||
}
|
||
```
|
||
|
||
### Units
|
||
|
||
| Unit | SCSI Meaning | IDE Meaning |
|
||
|---|---|---|
|
||
| 0 | SCSI ID 0 | Master |
|
||
| 1 | SCSI ID 1 | Slave |
|
||
| 2–6 | SCSI ID 2–6 | N/A |
|
||
| 7 | Host adapter (reserved) | N/A |
|
||
|
||
---
|
||
|
||
## Standard Commands
|
||
|
||
```c
|
||
/* Read 512 bytes from byte offset on disk: */
|
||
diskReq->io_Command = CMD_READ;
|
||
diskReq->io_Data = buffer;
|
||
diskReq->io_Length = 512;
|
||
diskReq->io_Offset = 0; /* byte offset */
|
||
DoIO((struct IORequest *)diskReq);
|
||
|
||
/* Write: */
|
||
diskReq->io_Command = CMD_WRITE;
|
||
diskReq->io_Data = buffer;
|
||
diskReq->io_Length = 512;
|
||
diskReq->io_Offset = 512;
|
||
DoIO((struct IORequest *)diskReq);
|
||
|
||
/* Flush write cache: */
|
||
diskReq->io_Command = CMD_UPDATE;
|
||
DoIO((struct IORequest *)diskReq);
|
||
```
|
||
|
||
> [!IMPORTANT]
|
||
> The `io_Offset` field is a `ULONG` (32-bit), limiting addressable space to **4 GB**. For larger drives, use TD64/NSD 64-bit commands.
|
||
|
||
---
|
||
|
||
## Direct SCSI Commands (HD_SCSICMD)
|
||
|
||
For operations beyond read/write — device identification, mode pages, CD-ROM commands:
|
||
|
||
```c
|
||
#include <devices/scsidisk.h>
|
||
|
||
struct SCSICmd scsicmd;
|
||
UBYTE cdb[10], sense[20], data[512];
|
||
|
||
/* READ(10) — read 1 sector at LBA 0: */
|
||
memset(cdb, 0, sizeof(cdb));
|
||
cdb[0] = 0x28; /* READ(10) opcode */
|
||
cdb[7] = 0; cdb[8] = 1; /* transfer length = 1 sector */
|
||
|
||
scsicmd.scsi_Data = (UWORD *)data;
|
||
scsicmd.scsi_Length = 512;
|
||
scsicmd.scsi_Command = cdb;
|
||
scsicmd.scsi_CmdLength = 10;
|
||
scsicmd.scsi_Flags = SCSIF_READ | SCSIF_AUTOSENSE;
|
||
scsicmd.scsi_SenseData = sense;
|
||
scsicmd.scsi_SenseLength = sizeof(sense);
|
||
|
||
diskReq->io_Command = HD_SCSICMD;
|
||
diskReq->io_Data = &scsicmd;
|
||
diskReq->io_Length = sizeof(scsicmd);
|
||
DoIO((struct IORequest *)diskReq);
|
||
|
||
if (scsicmd.scsi_Status != 0)
|
||
Printf("SCSI error: status=%ld, sense key=%ld\n",
|
||
scsicmd.scsi_Status, sense[2] & 0x0F);
|
||
```
|
||
|
||
### Common SCSI Commands
|
||
|
||
| Opcode | Name | CDB | Description |
|
||
|---|---|---|---|
|
||
| `0x00` | TEST UNIT READY | 6 | Check device readiness |
|
||
| `0x03` | REQUEST SENSE | 6 | Get error details |
|
||
| `0x12` | INQUIRY | 6 | Device identification |
|
||
| `0x1A` | MODE SENSE(6) | 6 | Read device parameters |
|
||
| `0x25` | READ CAPACITY | 10 | Get total sectors and sector size |
|
||
| `0x28` | READ(10) | 10 | Read sectors (32-bit LBA) |
|
||
| `0x2A` | WRITE(10) | 10 | Write sectors |
|
||
| `0x35` | SYNCHRONIZE CACHE | 10 | Flush write cache |
|
||
| `0x43` | READ TOC | 10 | Read CD table of contents |
|
||
| `0xBE` | READ CD | 12 | Read CD sector (any format) |
|
||
|
||
---
|
||
|
||
## CD-ROM Specifics
|
||
|
||
CD-ROM drives require special handling — they use ATAPI (IDE) or SCSI commands but with CD-specific extensions:
|
||
|
||
### Opening a CD-ROM
|
||
|
||
```c
|
||
/* CD-ROM is typically on a different device or unit: */
|
||
/* A1200 + ATAPI CD: */
|
||
OpenDevice("scsi.device", 2, req, 0); /* unit 2 = slave on second channel */
|
||
|
||
/* External SCSI CD: */
|
||
OpenDevice("2nd.scsi.device", 3, req, 0); /* SCSI ID 3 */
|
||
|
||
/* AmiCDFS or CacheCDFS handles mounting automatically via:
|
||
DEVS:DOSDrivers/CD0 mountlist entry */
|
||
```
|
||
|
||
### Reading the Table of Contents
|
||
|
||
```c
|
||
UBYTE tocData[804]; /* max TOC size */
|
||
memset(cdb, 0, 10);
|
||
cdb[0] = 0x43; /* READ TOC */
|
||
cdb[6] = 1; /* starting track */
|
||
cdb[7] = (sizeof(tocData) >> 8) & 0xFF;
|
||
cdb[8] = sizeof(tocData) & 0xFF;
|
||
|
||
scsicmd.scsi_Data = (UWORD *)tocData;
|
||
scsicmd.scsi_Length = sizeof(tocData);
|
||
scsicmd.scsi_Command = cdb;
|
||
scsicmd.scsi_CmdLength = 10;
|
||
scsicmd.scsi_Flags = SCSIF_READ | SCSIF_AUTOSENSE;
|
||
DoIO((struct IORequest *)diskReq);
|
||
```
|
||
|
||
### Audio CD Playback
|
||
|
||
```c
|
||
/* PLAY AUDIO MSF — play from start to end: */
|
||
memset(cdb, 0, 10);
|
||
cdb[0] = 0x47; /* PLAY AUDIO MSF */
|
||
cdb[3] = 0; /* start minute */
|
||
cdb[4] = 2; /* start second */
|
||
cdb[5] = 0; /* start frame */
|
||
cdb[6] = 60; /* end minute */
|
||
cdb[7] = 0; /* end second */
|
||
cdb[8] = 0; /* end frame */
|
||
|
||
scsicmd.scsi_Flags = SCSIF_READ;
|
||
DoIO((struct IORequest *)diskReq);
|
||
```
|
||
|
||
### CD Filesystem Drivers
|
||
|
||
| Driver | Type | Features |
|
||
|---|---|---|
|
||
| **AmiCDFS** | Free (Aminet) | ISO 9660, Rock Ridge, HFS, circular cache |
|
||
| **CacheCDFS** | OS 3.5+ / IDE-fix | ISO 9660, Rock Ridge, Joliet, HFS, LRU cache — de facto standard |
|
||
| **AsimCDFS** | Commercial | ISO 9660, High Sierra, Rock Ridge, HFS, CD-DA ripping, CDTV/CD32 emulation |
|
||
| **AllegroCDFS** | Elbox-bundled | ISO 9660 L1–3, Rock Ridge, Joliet, UDF, fastest benchmarks |
|
||
| **ODFileSystem** | Open source | ISO 9660, Rock Ridge, Joliet, UDF, HFS, HFS+ — modern replacement |
|
||
|
||
See [CD-ROM Filesystems](../07_dos/cdfs.md) for the full deep-dive: format coverage matrix, handler architecture, mount configuration, and decision guide.
|
||
|
||
---
|
||
|
||
## 64-Bit Addressing (TD64 / NSD)
|
||
|
||
For drives larger than 4 GB:
|
||
|
||
```c
|
||
/* TD64 — uses io_Actual for high 32 bits: */
|
||
diskReq->io_Command = NSCMD_TD_READ64;
|
||
diskReq->io_Data = buffer;
|
||
diskReq->io_Length = 512;
|
||
diskReq->io_Offset = lowOffset; /* low 32 bits */
|
||
diskReq->io_Actual = highOffset; /* high 32 bits */
|
||
DoIO((struct IORequest *)diskReq);
|
||
```
|
||
|
||
> [!TIP]
|
||
> **New Style Device (NSD)** provides a standard way to query 64-bit support: send `NSCMD_DEVICEQUERY` and check the returned command list.
|
||
|
||
---
|
||
|
||
## MiSTer / FPGA Notes
|
||
|
||
| Aspect | Implementation |
|
||
|---|---|
|
||
| IDE emulation | MiSTer emulates Gayle IDE — presents virtual ATA backed by SD card `.hdf` |
|
||
| SCSI emulation | A2091/A3000 SCSI cores map targets to `.hdf` files |
|
||
| Sector size | Must be 512 bytes — all Amiga drivers assume this |
|
||
| RDB | Rigid Disk Block at sectors 0–15 — must be present for HDToolBox |
|
||
| Performance | Virtual IDE is faster than real Gayle (no PIO bottleneck) |
|
||
|
||
---
|
||
|
||
## References
|
||
|
||
- NDK39: `devices/scsidisk.h`, `devices/trackdisk.h`
|
||
- ADCD 2.1: scsi.device autodocs
|
||
- SCSI-2 standard: ANSI X3.131-1994
|
||
- See also: [trackdisk.md](trackdisk.md) — floppy I/O (shares the same API model)
|
||
- See also: [CDTV Hardware](../01_hardware/ocs_a500/cdtv_hardware.md) — DMAC/WD33C93 SCSI CD-ROM controller
|
||
- See also: [Akiko — CD32](../01_hardware/aga_a1200_a4000/akiko_cd32.md) — CD32 CD-ROM controller (Akiko PIO, not SCSI)
|
||
- See also: [Gayle IDE & PCMCIA](../01_hardware/common/gayle_ide_pcmcia.md) — A600/A1200 IDE controller
|
||
- See also: [Gary — A3000](../01_hardware/ecs_a600_a3000/gary_system_controller.md) — A3000 SDMAC/WD33C93 SCSI integration
|
||
- See also: [CD-ROM Filesystems](../07_dos/cdfs.md) — CDFS handler deep-dive: ISO 9660, Rock Ridge, Joliet, UDF, handler comparison
|