| name | ody-io |
| description | Wire Wrap Odyssey memory map, peripherals, I/O, and storage reference. Use when working with memory addresses, peripheral registers, interrupts, video/color output, extended memory paging, FAT16 disk access, ODY executable format, printf format specifiers, color codes, or keyboard flags. |
| version | 1.0.0 |
Odyssey Memory Map, I/O, and Storage Reference
Memory Map
0x0000-0x3EFF Program ROM (16 KiB)
0x4000-0x4EFF Framebuffer characters (64x60 grid)
0x4F00-0x4FFF Hidden framebuffer (global variables)
0x5000-0x5EFF Framebuffer color (1 byte/char)
0x5F00-0x5F0F Interrupt vector table (8 x 16-bit)
0x5F10-0x5FFF Hidden framebuffer (global variables)
0x6000-0xBEFF ~24 KiB dynamic RAM (malloc region)
0xBF00-0xBFFF 256 bytes CPU hardware stack
0xC000-0xC7FF Peripheral registers (memory-mapped I/O)
0xC800-0xCAFF 768 bytes expanded RAM global assembly arrays
0xCB00-0xCBFF 256 bytes expanded RAM UART circular buffer
0xCC00-0xCCFF 256 bytes expanded RAM keyboard circular buffer
0xCD00-0xCFFF 768 bytes expanded RAM (free/future use)
0xD000-0xDFFF Extended RAM D-page window (4 KiB)
0xE000-0xEFFF Extended RAM E-page window (4 KiB)
0xF000-0xFFEF ~4 KiB expanded RAM heap/software stack
0xFFF0-0xFFFE Unallocated
0xFFFF Reserved (idle bus)
Peripherals
| Address | Peripheral |
|---|
| 0xC000-0xC001 | PS/2 Keyboard (0xC000=key, 0xC001=flags) |
| 0xC080-0xC0FF | RTC/Timer DS1511Y (BCD-encoded values) |
| 0xC100-0xC1FF | UART 82C52 (data, ctrl/status, modem ctrl, baud/modem status) |
| 0xC200-0xC2FF | Extended RAM page registers (even=D-page, odd=E-page) |
| 0xC300-0xC30F | ATA CS0/CS1 registers |
| 0xC310-0xC31F | ATA high byte latch (write hi first, lo write triggers 16-bit ATA write) |
Interrupts
8-line priority encoder. IRQ saves PC and D register to stack. RETI restores status flag backup.
| IRQ | Vector | Source |
|---|
| 1 | 0x5F02 | Keyboard |
| 3 | 0x5F06 | Timer |
| 4 | 0x5F08 | UART modem status |
| 5 | 0x5F0A | UART data ready |
IRQ 0/2/6/7 reserved.
Video
640x480 VGA, 64x60 character grid (8x8 chars, CP437 font). Dual-port SRAM: chars at 0x4000-0x4EFF, color at 0x5000-0x5EFF. Color byte: [BLINK][CURSOR][Rfg][Gfg][Bfg][Rbg][Gbg][Bbg] (64 colors + blink + cursor).
Extended Memory
1 MiB (two 512 KiB AS6C4008), accessed via two 4 KiB windows. D-window: 0xD000, page register at 0xC200 (even). E-window: 0xE000, page register at 0xC201 (odd). Physical = (page << 12) | (addr & 0x0FFF). Pages 0x000-0x7FF reserved for malloc ledger.
FAT16
Read-only FAT16 over ATA (PIO mode). Drives 0: and 1: (master/slave). 512-byte sectors, 28-bit LBA. 8.3 filenames (max 8-char command names).
ODY Executable Format
| Offset | Content |
|---|
| 0-2 | Magic: ODY |
| 3 | Flags (2 bits: memory target) |
| 4-5 | Count of relocation entries (16-bit) |
| 6+ | N x 16-bit relocation offsets, then raw machine code |
Loader adds base address to each relocation offset. CALL targets to ROM functions are absolute (not relocated).
printf Format Specifiers
%% literal, %c char, %2 binary, %b/%B BCD (1/2 digits), %x/%X hex (byte/word), %u/%U unsigned decimal (byte/word), %d/%D signed decimal (byte/word), %s string pointer.
Color Codes (:print strings)
@[shade:0-3][color:0-7] (0=blk 1=blu 2=grn 3=cyn 4=red 5=mag 6=yel 7=wht), @x[hex] raw, @b/@B blink off/on, @c/@C cursor off/on, @r reset.
Keyboard Flags (0xC001)
0x01 BREAK, 0x02 CTRL, 0x04 ALT, 0x08 FUNCTION, 0x10 SHIFT, 0x20 NUMLOCK, 0x40 CAPSLOCK, 0x80 SCROLLLOCK.
