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LT6502: A 6502-based homebrew laptop

A 6502 based laptop design

Yes, I know I'm crazy, but I figured why not. I'm enjoying working the PC6502 project but having a little tower of PCBs on the sofa isn't the best. It's very simple, these are the specs

  • 65C02 running at 8MHz
  • 46K RAM
  • BASIC in ROM
  • 65C22 VIA (for timers and some IO)
  • 9" DIsplay (with built in font/simple graphics)
  • Built in keyboard
  • Compact Flash for storage
  • 10000mAh battery built in
  • USBC powered/charged
  • Serial Console
  • 1 internal expansion slot

Assembled front view Picture of the assembled 6502 laptop in it's 3D printed case from the front Assembled rear view Picture of the assembled 6502 laptop in it's 3D printed case from the rear Assembled LHS view Picture of the assembled 6502 laptop in it's 3D printed case from the left hand side Assembled RHS view Picture of the assembled 6502 laptop in it's 3D printed case from the right hand side

Assembled closed front view Picture of the assembled 6502 laptop in it's 3D printed case from the front when closed Assembled closed rear view Picture of the assembled 6502 laptop in it's 3D printed case from the rear when closed

Lower parts (main board, battery, keyboard) in it's case Picture of the 6502 laptop base in it's 3D printed case Screen with BASIC code Picture of the 6502 laptop with screen and basic Jan 2026 First bring up Picture of the 6502 laptop as of 5th Jan 2026

  • 2025-11-12 - Initial commit with work in progress PCB, Schematics complete.
  • 2025-12-30 - PCBs arrived!
  • 2026-01-01 - Initial power up of PCBs gives all the correct voltages
  • 2026-01-03 - Bring up of board with simple ROM/RAM/Console working.
  • 2026-01-04 - VIA working, ACIA working, comms to/from the keyboard in basic working. Begun integrating keyboard into firmware
  • 2026-01-05 - Keyboard now integrated into firmware, so you can type on the keyboard and don't need the console for input
  • 2026-01-09 - Compact flash working, Beeper also now working. Also runs from battery just fine.
  • 2026-01-16 - Connected a 4.3" 800x480 RA8875 based display and got that working. I failed to get the LT7683 based display working.
  • 2026-01-17 - work on a number of case related things that did not quite work in actual life.
  • 2026-01-18 - Tweaked CPLD to slow down FTDI read/writes. Also begun work on bios, added start beep and begun work on load/save functions
  • 2026-02-08 - Added more commands, notably SAVE,LOAD and DIR for compact flash
  • 2026-02-13 - Added more graphics commands :)
  • 2026-02-14 - Assembled the case
  • Expansion board

To do (probably in order)

  • add in larger display (going to try a 10.1" RA8889 based 1024x600, fall back is a 9" RA8875 based 800x480)
  • Fix buggy keyscan code on MEGA644P

The memory map is fairly stable at the moment, everything seems to be working fine.

Start End Size (Dec) Size (Hex) What is it Notes
0x0000 0xBEAF 48816 0xBEB0 RAM This includes Zeropage and other bits BASIC may need (more below)
0xBE00 0xBFFF 512 0x200 peripherals This is where the peripherals are mapped (see below)
0xC000 0xFFFF 12288 0x3000 ROM holding EhBASIC, eWoz monitor, bootstrap and vectors
Start End Size (Dec) Size (Hex) What is it Notes
0xC000 0xFAFF 15104 0x3B0 EhBASIC EhBASIC 2.22p5
0xF000 0xF2FF 768 0x300 eWozMon Enhanced Wozmon
0xF300 0xFFF9 3322 0xCFA Bootstrap startup messages and also input/output/load/save functions
0xFFFA 0xFFFF 6 0x0A 6502 Vectors
Start End Size (Dec) Size (Hex) What is it Notes
0x0000 0x02FF 768 0x300 RAM This includes Zeropage and other bits BASIC may need
0x0300 0x07FF 1280 0x500 RAM This is going to be for the compact flash reading/writing
0x0800 0xBDFF 46592 0xB6B0 ROM BASIC RAM available
Address subAddr range RW What is it Notes
0xBE0O 00-FF RW Expansion slot
0xBF00 00-9F Unused Currently
0xBFAO 0-0 W Beeper just write 0xFF and 0x00 to turn on/off the speaker
0xBFBO 0-7 RW Compact Flash
0xBFCO 0-F RW 65C22 on board VIA
0xBFDO 0-F 0-1 Display
0xBFEO 0-F RW 65C21 internal keyboard
0xBFF0 0-1 RW Console FTDI USB console port

I've Added a some extra commands to EhBASIC and they are as follows;

  • BEEP P,L - Pitch (P) is 0-255, length (L) = 0 to 255
  • CIRCLE X,Y,R,C,F - Draws a Circle, X is 0-799, Y is 0-479, R(radius) is 1 - 65535, C is 8bit RGB Value (RRRGGGBB), F is fill (0 = no fill, 1 = fill)
  • CLS - Clear screen (both graphic and text mode)
  • COLOUR <0-255> - Sets the colour (text) to 8bit RGB value, in the form RRRGGGBB
  • DIR - Scans the Compact Flash card and shows slot number and name for any files present
  • ELIPSE - X,Y,RX,RY,C,F - Draws an elipse, X is 0-799, Y is 0-479, RX is X radius, RY is Y radius, C is colour and F is fill
  • LINE X,Y,EX,EY,C - Draws a line, X is 0-799, Y is 0-479, EX is X end point (0-799), EY is Y end point (0-479), C is colour
  • LOAD <0-2047> - LOAD a file from CF
  • MODE <0,1> - Sets the display mode, MODE 0 is text, MODE 1 is graphics
  • OUTK - Outputs Text to the 8 character display on the keybed, can be a string or value, anything more than 8 characters will result in text shifting. a String will clear the display and then output the characters
  • PLOT X,Y,C - Plots a dot, X is 0-799, Y is 0-479 and C is 8bit RGB Value (RRRGGGBB)
  • SAVE <0-2047>,"" - SAVE current BASIC program into a SLOT and give it a name, upto 16 characters
  • SQUARE - X,Y,EX,EY,C,F - Draws a square, X is 0-799, Y is 0-479, EX is X end point (0-799), EY is Y end point (0-479), C is colour and F is fill
  • WOZMON - Jumps to wozmon, Q will exit WOZMON and return to basic (Handy for check chunks of memory)