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--- sd:sd-8516_programmer_s_reference_guide [2026/02/25 02:35] – appledog
+++ sd:sd-8516_programmer_s_reference_guide [2026/02/25 02:44] (current) – appledog
@@ Line 339: / Line 339: @@
 == Appendix 3. Memory Map
-=== Bank Addressing
+Placed in it's own section for easy reference:
-The SD-8516 supports 4 banks of 64KB each (256KB total) through special addressing modes:
+* [[Appendix 3 Memory Map]]
-<codify armasm>
-        ; ld/st example
-        LDA [I:J]        ; Load from bank I, offset J
-        STA [2:$1000]    ; Store to bank 2, offset $1000
-</codify>
-**Bank allocation:**
-* Bank 0: User Programming Space
-* Bank 1: KERNAL and Operating System
-* Bank 2: Primary video framebuffer + palette
-* Bank 3: Secondary video buffer (high-resolution modes)
-Banks 2 and 3 are free for use in text mode and bank 3 is usually free in the lower-resolution video modes.
-=== System Variables
-|= Address |= Description |
-| $EF00 | Video mode register |
-| $EF01 | Column count (40 or 80) |
-| $EF02 | Row count (25) |
-| $EF03 | Character width (8) |
-| $EF04 | Character height (8) |
-| $EF05-$EF08 | Hardware clock (32-bit milliseconds) |
-| $EF09 | Default character color |
-| $EF0A | Cursor color |
-| $EF0B | Color palette mode (0=COLORDORE, 1=CGA 5153) |
-| $EF10 | Cursor X position |
-| $EF11 | Cursor Y position |
-| $EF12 | Cursor blink state |
-| $EF20 | Keyboard status flags |
-| $EF21 | Keyboard buffer count |
-| $EF22-$EF31 | Keyboard buffer (16 bytes) |
-=== Memory Map
-^ **BANK 0 - User RAM & System Variables** ||||
-^ Address ^ Size (Bytes) ^ Name ^ Description |
-| $000000-$00FFFF | 65,536 | USER_RAM | Free user RAM |
-^ **BASIC Program Storage** ||||
-| $000100-$00FF00 | 65,024 | BASIC_START | BASIC program area |
-^ **BANK 1 - KERNAL ROM & Hardware** ||||
-^ Address ^ Size ^ Name ^ Description |
-| $010000-$0100FF | 256 | BOOTSTRAP | Kernal zero page (reserved) |
-| $010100-$013FFF | ~16KB | KERNAL_CODE | Soft Reset entry point |
-| $014000-$01DBFF | 40,960 | RESERVED | Future kernal expansion |
-| $01DB00-$01DBFF | 256 | PATB_TBUF | ROM BASIC tokenizer scratch |
-| $01DC00-$01DFFF | 1,024 | STACK | Stack space (grows down from $01DFFF) |
-| $01E000-$01E7FF | 2,048 | VM1_CHAR_ROM | PETSCII font data |
-| $01E800-$01E8FF | 256 | KERNAL_WORK | Kernal workspace |
-| $01E900-$01EBFF | 768 | INT_VECTOR_TABLE | Interrupt vectors (256 × 3 bytes) |
-| $01EC00-$01ECFF | 256 | SCRATCH_BUFFER | General-purpose scratch space |
-| $01ED00-$01EDFF | 256 | INPUT_BUFFER | Input line buffer / Kernal variables |
-^ **Video System** ||||
-| $01EF00 | 1 | VIDEO_MODE | Current video mode |
-| $01EF01 | 1 | VIDEO_COLUMNS | Number of columns (40) |
-| $01EF02 | 1 | VIDEO_ROWS | Number of rows (25) |
-| $01EF03 | 1 | VIDEO_CHAR_WIDTH | Character width in pixels (8) |
-| $01EF04 | 1 | VIDEO_CHAR_HEIGHT | Character height in pixels (8) |
-| $01EF05-$01,EF08 | 4 | VIDEO_HW_CLOCK | Hardware clock (32-bit milliseconds) |
-| $01EF09 | 1 | VIDEO_CHAR_COLOR | Default character color |
-| $01EF0A | 1 | VIDEO_CURSOR_COLOR | Cursor color |
-| $01EF0B | 1 | VIDEO_COLOR_MODE | Color palette mode |
-|= **Cursor System** ||||
-| $01EF0C | 1 | CURSOR_BLINK | Cursor blink state |
-| $01EF0D | 1 | CURSOR_STATE | Cursor on/off |
-| $01EF0E | 1 | CURSOR_X | Cursor column |
-| $01EF0F | 1 | CURSOR_Y | Cursor row |
-|= **Keyboard System** ||||
-| $01EF10 | 1 | KBD_BUFFER_COUNT | Number of keys in buffer |
-| $01EF11-$01,EF30 | 32 | KBD_BUFFER | Key buffer (16 pairs) |
-|= **Input Mode System** ||||
-| $01EF31 | 1 | INPUT_MODE | Input mode flag (0=normal, 1=input) |
-| $01EF32 | 1 | INPUT_LENGTH | Current input length |
-| $01EF33 | 1 | SYSCALL_STATUS | Execute SYS on next opportunity |
-| $01EF34-$01,EF36 | 3 | SYSCALL_ADDR | SYS call address |
-| $01EF37-$01,EF39 | 3 | KBPC | BASIC code pointer |
-|= **Random Number Generator** ||||
-| $01EF40-$01,EF41 | 2 | RND_SEED | PRNG seed |
-|= **Sound System - Voice 0** ||||
-| $01EF80-$01,EF81 | 2 | SOUND0_FREQUENCY | Voice 0 frequency |
-| $01EF82 | 1 | SOUND0_GATE | Voice 0 gate/waveform |
-| $01EF83 | 1 | SOUND0_VOLUME | Voice 0 volume |
-| $01EF84 | 1 | SOUND0_ATTACK | Voice 0 attack |
-| $01EF85 | 1 | SOUND0_DECAY | Voice 0 decay |
-| $01EF86 | 1 | SOUND0_SUSTAIN | Voice 0 sustain |
-| $01EF87 | 1 | SOUND0_RELEASE | Voice 0 release |
-| $01EF88-$01,EF89 | 2 | SOUND0_DATA | Voice 0 data |
-|= **Sound System - Voice 1** ||||
-| $01EF90-$01,EF91 | 2 | SOUND1_FREQUENCY | Voice 1 frequency |
-| $01EF92 | 1 | SOUND1_GATE | Voice 1 gate/waveform |
-| $01EF93 | 1 | SOUND1_VOLUME | Voice 1 volume |
-| $01EF94 | 1 | SOUND1_ATTACK | Voice 1 attack |
-| $01EF95 | 1 | SOUND1_DECAY | Voice 1 decay |
-| $01EF96 | 1 | SOUND1_SUSTAIN | Voice 1 sustain |
-| $01EF97 | 1 | SOUND1_RELEASE | Voice 1 release |
-| $01EF98-$01,EF99 | 2 | SOUND1_DATA | Voice 1 data |
-|= **Sound System - Voice 2** ||||
-| $01EFA0-$01,EFA1 | 2 | SOUND2_FREQUENCY | Voice 2 frequency |
-| $01EFA2 | 1 | SOUND2_GATE | Voice 2 gate/waveform |
-| $01EFA3 | 1 | SOUND2_VOLUME | Voice 2 volume |
-| $01EFA4 | 1 | SOUND2_ATTACK | Voice 2 attack |
-| $01EFA5 | 1 | SOUND2_DECAY | Voice 2 decay |
-| $01EFA6 | 1 | SOUND2_SUSTAIN | Voice 2 sustain |
-| $01EFA7 | 1 | SOUND2_RELEASE | Voice 2 release |
-| $01EFA8-$01EFA9 | 2 | SOUND2_DATA | Voice 2 data |
-|= **Sound System - Voice 3** ||||
-| $01EFB0-$01EFB1 | 2 | SOUND3_FREQUENCY | Voice 3 frequency |
-| $01EFB2 | 1 | SOUND3_GATE | Voice 3 gate/waveform |
-| $01EFB3 | 1 | SOUND3_VOLUME | Voice 3 volume |
-| $01EFB4 | 1 | SOUND3_ATTACK | Voice 3 attack |
-| $01EFB5 | 1 | SOUND3_DECAY | Voice 3 decay |
-| $01EFB6 | 1 | SOUND3_SUSTAIN | Voice 3 sustain |
-| $01EFB7 | 1 | SOUND3_RELEASE | Voice 3 release |
-| $01EFB8-$01EFB9 | 2 | SOUND3_DATA | Voice 3 data |
-|= **Video Memory** ||||
-| $01F000-$01F3E7 | 1,000 | VM1_TEXT_BASE | Text mode character map |
-| $01F800-$01FBE7 | 1,000 | VM1_COLOR_BASE | Text mode color map |
-|= **BANK 2 & 3 - User RAM** ||||
-| $020000-$02FFFF | 65,536 | USER_RAM | Free user RAM (Bank 2) |
-| $030000-$03FFFF | 65,536 | USER_RAM | Free user RAM (Bank 3) |
 == Appendix 4. Instruction Set Architecture