notes

notes/color-video.md

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+# Color Video
+- 307_200/0x4_B000 Bytes needed (!)
+- fits into 9\*32K RAM chips
+- alternative 5\*64K RAM chips, 32K additional usable memory
+- alternative 2\*128K RAM + 1\*32K RAM
+- consider: memory needs to be duplicate
+
+# TR9C1710

notes/input-output.md

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+# I/O
+- Intel-P8254 (Programmable Interval Timer)
+- NEC-uPB8214C (Priority Interrupt Controller)
+- 6522 (VIA)
+- 6551 (ACIA)

notes/memory-layout.md

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+# Memory Layout
+- bank switching using 8-Bit register
+- top 32K remain untouched
+
+| start  | end    | use |
+| :----- | :----- | :-- |
+| 0x8000 | 0xDFFF | RAM |
+| 0xE000 | 0xFFFF | ROM |
+
+# Default (0X00)
+| start  | end    | use |
+| :----- | :----- | :-- |
+| 0x0000 | 0x7FFF | I/O |
+
+# Persistent Memory (0x01)
+| start  | end    | use     |
+| :----- | :----- | :------ |
+| 0x0000 | 0x7FFF | storage |
+
+# Monochrome Video (0x0E, 0x0F)
+| start  | end    | use              |
+| :----- | :----- | :--------------- |
+| 0x0000 | 0x4AFF | VRAM             |
+| 0x6000 | 0x7FFF | character memory |
+
+# Color Video
+| start  | end    | use              |
+| :----- | :----- | :--------------- |
+| 0x0000 | 0x4AFF | VRAM             |
+| 0x6000 | 0x7FFF | character memory |

notes/monochrome-video.md

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+# Monochrome Video
+- need 307_200 bits => 38_400/0x9600 Bytes 
+- 8K character memory
+
+- 1x 64K RAM
+- split in half
+- each half into page (0x0000 - 0x4AFF)
+- map character memory into top (0x6000 - 0x7FFF)
+
+## Design
+- derive CS from bank register, leave LSB free -> wire to MSB of VRAM address

notes/persistent-memory.md

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+# Memory
+- maybe implement filesystem

notes/vga.md

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+# VGA
+## Timings
+### General Timings
+| Attribute           | Value       |
+| :------------------ | :---------- |
+| Screan refresh rate | 60Hz        |
+| Vertical refresh    | 31.46875kHz |
+| Pixel frequency     | 25.175 MHz  |
+
+### Horizontal Timings (line)
+| Scanline part | Pixels | Time [us]        |
+| :------------ | :----- | :--------------- |
+| Visible area  | 640    | 25.422045680238  |
+| Front porch   | 16     | 0.63555114200596 |
+| Sync Pulse    | 96     | 3.8133068520357  |
+| Back Porch    | 48     | 1.9066534260179  |
+| Whole line    | 800    | 31.777557100298  |
+
+### Vertical timing (frame)
+| Frame part   | Lines | Time [ms]         |
+| :----------- | :---- | :---------------- |
+| Visible Area | 480   | 15.253227408143   |
+| Front porch  | 10    | 0.31777557100298  |
+| Sync pulse   | 2     | 0.063555114200596 |
+| Back porch   | 33    | 1.0486593843098   |
+| Whole frame  | 525   | 16.683217477656   |
+
+## Additional Data
+- 640*480 = 307_200