LT6502: A 6502-based homebrew laptop

Hacker News · Feb 15, 2026 · Collected from RSS

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LT6502 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 Pictures Assembled front view Assembled rear view Assembled LHS view Assembled RHS view Assembled closed front view Assembled closed rear view Lower parts (main board, battery, keyboard) in it's case Screen with BASIC code First bring up Status 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 In Progress 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 Memory Map The memory map is fairly stable at the moment, everything seems to be working fine. High Level 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 ROM breakdown 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 RAM breakdown 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 peripherals 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 EhBASIC Extra commands 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)