Peripherals and models description improved and expanded

01_hardware/ocs_a500/README.md

@@ -25,6 +25,65 @@ The **Original Chip Set** (OCS) ships in the Amiga 1000 (1985), A500 (1987), and
 | [paula_audio.md](paula_audio.md) | Audio DMA: AUDxLCH/LCL/LEN/PER/VOL, interrupt |
 | [paula_serial.md](paula_serial.md) | Serial port: SERPER/SERDATR, baud rate |
 | [sprites.md](sprites.md) | Hardware sprites: SPRxPTH, control words, attach mode |
+| [cdtv_hardware.md](cdtv_hardware.md) | CDTV platform: DMAC, CD-ROM, IR remote, NVRAM |
+
+---
+
+## OCS Machines — Per-Model Details
+
+### A1000 (1985) — Writable Control Store
+
+The A1000 is the original Amiga. Its most distinctive feature is the **Writable Control Store (WCS)** — Kickstart is loaded from floppy into RAM at every cold boot, rather than residing in ROM.
+
+| Feature | Details |
+|---|---|
+| CPU | 68000 @ 7.09 MHz |
+| Chip RAM | 256 KB base (daughterboard adds 256 KB = 512 KB total) |
+| Kickstart | Loaded from floppy into 256 KB WCS RAM at `$F80000` |
+| Bootstrap ROM | 256 bytes at `$FC0000` — just enough to load Kickstart from floppy |
+| Expansion | 86-pin sidecar bus (predecessor to Zorro) |
+
+**WCS boot process:**
+1. Power on → bootstrap ROM displays "Insert Kickstart disk"
+2. User inserts Kickstart 1.x floppy
+3. Bootstrap loads 256 KB Kickstart image into WCS RAM
+4. Hardware write-protect latch activates → WCS becomes read-only
+5. System resets and boots from the now-protected WCS as if it were ROM
+
+> [!NOTE]
+> The WCS is the reason the A1000 can run different Kickstart versions without swapping ROM chips. Third-party "Kickstart Eliminators" add actual ROM chips, bypassing the floppy-loading step entirely.
+
+The A1000 daughterboard (256 KB Chip RAM expansion) sits inside the case on top of the motherboard. The 86-pin sidecar connector on the right side accepts external expansion chassis for memory, hard drives, and other peripherals.
+
+### A2000 (1987) — The Expandable Workhorse
+
+The A2000 is the first "big-box" Amiga, designed for professional expansion. It shipped in two major variants:
+
+| Variant | Board Revisions | Chipset | Chip RAM | Notes |
+|---|---|---|---|---|
+| **A2000-A** (German) | Rev 3.x | OCS (Agnus 8361) | 512 KB | Original design by Commodore Germany |
+| **A2000-B** (US) | Rev 4.x | OCS (Fat Agnus 8370/8372) | 512 KB + 512 KB slow | Redesigned for US market |
+| **A2000-C** | Rev 6.x | ECS (Super Agnus 8372A) | 1 MB Chip | Late production with ECS chips |
+
+#### Expansion Architecture
+
+| Slot Type | Count | Bus Width | Address Space | Description |
+|---|---|---|---|---|
+| **Zorro II** | 5 | 16-bit | `$200000`–`$9FFFFF` (8 MB) | Autoconfig expansion cards |
+| **CPU slot** | 1 | Direct 68000 | — | Directly wired to CPU socket — accepts accelerators (A2630, GVP G-Force) |
+| **Video slot** | 1 | 36-pin | — | Internal video signals for genlocks and framebuffers |
+| **ISA (PC bridgeboard)** | 2 | 8/16-bit | — | For A2088/A2286 PC compatibility cards |
+
+The CPU slot is the A2000's most important expansion feature. Accelerator cards plug directly into the 68000 socket, replacing the CPU with 68020/030/040/060 processors. This makes the A2000 the most upgradeable classic Amiga.
+
+> [!NOTE]
+> Late A2000 boards (rev 6+) shipped with ECS chips and are sometimes listed under ECS. Architecturally they remain A2000 boards with the same Zorro II bus and expansion layout.
+
+### CDTV (1991) — CD-ROM Set-Top Box
+
+The CDTV is an A500-class OCS computer in a consumer set-top box form factor. See the dedicated article: **[CDTV Platform Hardware](cdtv_hardware.md)** — covers the DMAC/WD33C93 SCSI CD-ROM controller, 512 KB Extended ROM, 64 KB NVRAM, infrared remote, and real-time clock.
+
+---
 
 ## OCS Limitations vs ECS/AGA