Imported from GitHub: tkhshmsy/sbc6502a1 · commit dd4db09 · license MIT
Description
Single Board Computer using W65C02
README
sbc6502a1
Single Board Computer with 65C02, clone of Apple I
Features
- Clone of Apple I.
- similar but much ** greater ** projects are there.
- Communicate with Host-PC via Serial.
- using Arduino Nano as PIA Communicator
- 32KB user RAM is available.
- ROM has 2 bank of each 8KB + 8KB.
- it is enough for wozmon, Apple1-BASIC, OSI-BASIC and so on.
- Power supply +5VDC from Type-C or via Arduino Nano.
PCB
Schematics and Layout
BOM
| Ref | Name | Qty | Description | Package | Link |
|---|---|---|---|---|---|
| U1 | W65C02S | 1 | MPU 6502 | DIP40 | akizuki, mouser |
| U2 | W65C21S | 1 | PIA 6521 | DIP40 | mouser |
| U3 | 74HC04 | 1 | DIP14 | akizuki | |
| U4 | 74HC00 | 1 | DIP14 | akizuki | |
| U5 | 74HC138 | 1 | DIP16 | akizuki | |
| U6 | 62256 | 1 | SRAM 32Kx8 | DIP28 | mouser AS6C62256-55PCN, uPD43256AC-12L-13P |
| U7 | 27C512 | 1 | ROM 64Kx8 | DIP28 | W27C512-45(EEPROM), mouser AT27C512R-45PU(OTP-EPROM) |
| U8 | MCP23S17 | 1 | SPI/GPIO | DIP28/300mil | akizuki |
| A1 | Arduino Nano | 1 | PIA Communicator | akizuki, other clones | |
| X1 | 1.0 MHz | 1 | Crystal OSC | DIP8 | akizuki 1MHz |
| C1 | 0.01uF-0.1uF | 1 | |||
| C2, C4, C5, C6, C7, C8, C9, C10, C11 | 0.1uF | 9 | |||
| C3 | 470uF | 1 | |||
| D1 | 1N4148 | 1 | DO35 | ||
| J1 | 2x20 Pin Header | 1 | Bus export | ||
| J2 | USB Type-C Power | 1 | Power Supply | akizuki | |
| J3 | 1x6 Pin Header | 1 | for Serial comm | ||
| JP1, JP2 | 1x2 Pin Header | 1 | jumper select | ||
| R1, R2, R3, R4 | 10K-100K | 4 | for pullup | ||
| RN1 | 10Kx8 | 1 | for pullup | ||
| SW1 | Push Button | 1 | Reset SW | ||
| SW2 | Slide Switch | 1 | Power SW | akizuki | |
| TP1,TP2 | Test Pin | 2 |
Note: Clock Frequency
- Original Apple1 works at 1.0 MHz
- This PCB works fine at 1.0 - 10.0 MHz
- These clocks have been TESTED with a1basic, OSI-BASIC etc.
- Using faster RAM and ROM, It may work even at 14 MHz, which is the limit of MPU and PIA.
Memory Map
System
| Address | Size | Name | Note |
|---|---|---|---|
| 0x0000 - 0x7FFF | 32KB | RAM | |
| 0x8000 - 0x87FF | 2KB | (N.C.) | /CS80 |
| 0x8800 - 0x8FFF | 2KB | (N.C.) | /CS88 |
| 0x9000 - 0x97FF | 2KB | (N.C.) | /CS90 |
| 0x9800 - 0x9FFF | 2KB | (N.C.) | /CS98 |
| 0xA000 - 0xBFFF | 8KB | ROM | mapped from 0x2000 or 0xA000 |
| 0xC000 - 0xC7FF | 2KB | (N.C.) | /CSc0 |
| 0xC800 - 0xCFFF | 2KB | (N.C.) | /CSc8 |
| 0xD000 - 0xD7FF | 2KB | PIA | assigned to 0xD010 |
| 0xD800 - 0xDFFF | 2KB | (N.C.) | /CSd8 |
| 0xE000 - 0xFFFF | 8KB | ROM | mapped from 0x6000 or 0xE000 |
ROM (27C512 64KB)
| Address | Bank | Note |
|---|---|---|
| 0x0000 - 0x1FFF | Bank0 (JP1 open) | no use |
| 0x2000 - 0x3FFF | 8KB, mapped to 0xA000 | |
| 0x4000 - 0x5FFF | no use | |
| 0x6000 - 0x7FFF | 8KB, mapped to 0xE000 | |
| 0x8000 - 0x9FFF | Bank1 (JP1 close) | no use |
| 0xA000 - 0xBFFF | 8KB, mapped to 0xA000 | |
| 0xC000 - 0xDFFF | no use | |
| 0xE000 - 0xFFFF | 8KB, mapped to 0xE000 |
License
- MIT
- only for PCB
- firmwares are NOT included.
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