LB-6802-01

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LB-6802-01 P1670-720PX.jpg

Features

  • 68B02 CPU
    • 2 MHz clock
    • MC6802 is fully compatible with MC6800 but without messy two-phase clocking

Memory Map

  • 0x0000-0x7FFF 32KB SRAM
  • 0x8000-0xBFFF Serial (68B50 ACIA)
  • 0xC000-0xFFFF 16KB EPROM

Design

CPU

LB-6802-01 CPU.PNG

MC6800 Block Diagram

Mc6800 processor diagram.png

Bus Timing

Timing 68B02.PNG

Power Supervisor/Reset

LB-6802-01 RESET PWR SUPER.PNG

PLD

LB-6802-01 PLD.PNG

PLD Listing

Name       LB-6802-01_PLD;
Partno     ATF16V8B;
Date       09/02/24;
Revision   01;
Designer   DOUG G;
Company    LAND BOARDS LLC;
Assembly   LB680201_U2;
Location   Rustbelt, US;
Device     G16V8;

/*
*/


/* Control inputs */
PIN    1   = CLK;
PIN    2   = CPUA12;
PIN    3   = CPUA13;
PIN    4   = CPUA14;
PIN    5   = CPUA15;
PIN    6   = CPUREAD;
PIN    7   = VPB;		/* Added as wire on Rev 1 PCB	*/
PIN    8   = VPA;
PIN    9   = VDA;

/* Address Decode and Chip Select outputs */
PIN    12  = !ROMCS;
PIN    13  = !IOCS;
PIN    14  = !MEMRD;
PIN    16  = !RAMCS;
PIN    18  = RDY;

ROMCS = CPUA15 & CPUA14 & CPUREAD;

RAMCS = !CPUA15 & CPUREAD		/* 0x0000-0x7FFF 32KB SRAM	*/
#       !CPUA15 & !CPUREAD & VPB;	/* 0x0000-0x7FFF Free (8KB	*/

IOCS = CPUA15 & !CPUA14 & !CPUA13 &  CPUREAD		 /* 0x8000-0x9FFF Serial (ACIA)	*/
#      CPUA15 & !CPUA14 & !CPUA13 & !CPUREAD & VPB;

RDY = VPB;

MEMRD = CPUREAD;

Backplane Connector

LB-6802-01 BKPL.PNG

Software

Builds

  • SMITHBUG is a debugger similar to MIKBUG
    • Examine/Edit memory
    • Disassembly code
    • Download S record (V2)
    • Run code
  • FIG-Forth - Forth language
  • Combined SMITHBUG and FIG-Forth build

Building Code

  • Uses a68 assembler
    • Command line makes S-Record output
  • Use srec_cat to shift from EPROM absolute addresses to 0x0000 as HEX file
  • Or shift in the EPROM programmer


SmithBUG Builds for LB-6802-01 CPU Card

4KB Build

A68 SMITHBUG_SIMPLE-6802_F000.ASM -l SMITHBUG_SIMPLE-6802_F000.LST -s SMITHBUG_SIMPLE-6802_F000.S
srec_cat SMITHBUG_SIMPLE-6802_F000.s -offset - -minimum-addr SMITHBUG_SIMPLE-6802_F000.s -o smithbug_F000.hex -Intel

SmithBUG Commands

;	V	VIEW MEMORY
;	E	CHANGE MEMORY
;	I	FILL MEMORY
;	M	MOVE MEMORY
;	D	DISASSEMBLE CODE
;	G	GO TO PROGRAM
;	R	PRINT
;	@	ASCII CONVERSION
;	H	PRINTER ON
;	J	JUMP TO TARGET PROGRAM
;	F	FIND 
;	Q	HARDWARE LOCATION
;	T	TRACE PROGRAM
;	1	BREAKPOINT ONE
;	2	BREAKPOINT TWO
;	K	CONTINUE AFTER BREAK
;	&	S1 LOAD PROGRAM
;	*	HARDWARE LOCATION (TBA)
;	O	ECHO ON
;	N	ECHO OFF

FIGFORTH in RAM

&
  • Using TermTerm, File, Send File
  • Send fig-FORTH_6800.s19
  • Type S9 to exit srecord loader
  • Type J 1000 to jump to address 0x1000
  • Responds with
Forth-68
1 1 + . 2  OK

TASK   FORTH   NOOP   VLIST   TRIAD   INDEX   LIST   ?   .   D.   D.R   .R   #S   #   SIGN   #>   <#
SPACES   WHILE   ELSE   IF   REPEAT   AGAIN   END   UNTIL   +LOOP   LOOP   DO   THEN   ENDIF   BEGIN
BACK   FORGET   '   R/W   HI   LO   BLOCK_READ   BLOCK_WRITE   ?DISC   -->   LOAD   MESSAGE   .LINE
(LINE)   BLOCK   BUFFER   DR1   DR0   EMPTY-BUFFERS   UPDATE   +BUF   PREV   USE   DABS   ABS   M/MOD
*/   */MOD   MOD   /   /MOD   *   S->D   COLD   ABORT   QUIT   (   DEFINITIONS   VOCABULARY   IMMEDIATE
INTERPRET   DLITERAL   LITERAL   [COMPILE]   CREATE   ID.   ERROR   (ABORT)   -FIND   NUMBER   (NUMBER)
WORD   PAD   HOLD   BLANKS   ERASE   FILL      QUERY   EXPECT   ?STACK   ."   (.")   -TRAILING   TYPE
COUNT   DOES>   <BUILDS   ;CODE   (:CODE)   DECIMAL   HEX   SMUDGE   ]   [   COMPILE   ?LOADING   ?CSP
?PAIRS   ?EXEC   ?COMP   ?ERROR   !CSP   PFA   NFA   CFA   LFA   LATEST   TRAVERSE   -DUP   MAX   MIN
SPACE   ROT   >   <   =   -   C,   ,   ALLOT   HERE   2+   1+   COLUMNS   HLD   R#   CSP   FLD   DPL
BASE   STATE   CURRENT   CONTEXT   OFFSET   SCR   OUT   IN   BLK   VOC-LINK   DP   FENCE   WARNING
WIDTH   TIB   R0   S0   +ORIGIN   B/SCR   B/BUF   LIMIT   FIRST   BL   3   2   1   0   USER   VARIABLE
CONSTANT   ;   :   C!   !   C@   @   TOGGLE   +!   DUP   SWAP   DROP   OVER   DMINUS   MINUS   D+   +
0<   0=   R   R>   >R   LEAVE   ;S   RP!   SP!   SP@   XOR   OR   AND   U/   U*   CMOVE   CR   ?TERMINAL
KEY   EMIT   ENCLOSE   (FIND)   DIGIT   I   (DO)   (+LOOP)   (LOOP)   0BRANCH   BRANCH   EXECUTE   LIT    OK

SMITHBUG and FIGFORTH in ROM

  • Combines SMITHBUG and FIGFORTH in ROM
  • Combined Source code
    • SMITHBUG in ROM from 0xC000-0xCFFF
    • FIGFORTH in ROM from 0xD000-0xEFFF
    • Vectors are at top of ROM from 0xFFF8-0xFFFF
  • Fixes in FIG-Forth to get it to run from ROM
    • The comments in the file indicated it could be run from ROM but the stack pointed to ORIG which is in ROM
    • Fixed addresses of stack and I/O pointer to get it to work from ROM
  • SMITHBUG and FIGFORTH in ROM GitHub
  • Assemble
A68 SMITHBUG_FORTH_SIMPLE-6802_C000.ASM -l SMITHBUG_FORTH_SIMPLE-6802_C000.LST -s SMITHBUG_FORTH_SIMPLE-6802_C000.S
6800/6801 Cross-Assembler (Portable) Ver 3.5!
Copyright (c) 1985 William C. Colley, III
fixes for LCC/Windows and improvement by HRJ Aug 26 2019
A68 source_file | -l list_file | | -o/-s object_file |

No Errors
  • Edit out RAM at top
  • Make hex file
srec_cat SMITHBUG_FORTH_SIMPLE-6802_C000.s -offset - -minimum-addr SMITHBUG_FORTH_SIMPLE-6802_C000.s -o SMITHBUG_FORTH_SIMPLE-FC.hex -Intel
srec_cat: SMITHBUG_FORTH_SIMPLE-6802_C000.s: 1: warning: no header record
srec_cat: SMITHBUG_FORTH_SIMPLE-6802_C000.s: 1: warning: no header record
  • Boots to SMITHBUG
  • Type J D000 to run Fig-Forth or
  • Type 4 to run Forth

TinyBASIC

Mechanicals

LB-6802-01 CAD Rev1.PNG

Checkout

Rev 1

  • Power supply noise trips voltage monitor
    • Change C2 capacitor to 100 uF
  • [LB-BKOUT-01#NOP_Tester|NOP Tester] worked

Assembly Sheet

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