LB-6809-01

Features

• 68B09 CPU
• 8 MHZ crystal on card
  • CPU runs at 2 MHz
• Reset switch/power monitor
• Address decoder PLD drives RAM/ROM/IO chip selects
• 100x50mm card

Memory Map

• 0x0000-0x7FFF 32KB SRAM
• 0x8000-0x9FFF Free Space (8KB)
  • Could be mapped in the PLD to EPROM or SRAM (with LB-MEM-04 card)
• 0xA000-0xBFFF Serial (ACIA)
• 0xC000-0xFFFF 16KB EPROM

Design

68B09 CPU

• 8 MHz clock using crystal and built-in oscillator
  • Runs effectively at 2 MHz

CPU

CPU Timing

Crystal

• Uses CPU internal oscillator

PLD

• ATF16V8B part
• TL866ii Plus Programmer

PLD Listing

• Latest PLD source code here
• Added code to blink LED

Name       LB-6809-01_PLD;
Partno     ATF16V8B;
Date       09/07/24;
Revision   01;
Designer   DOUG G;
Company    LAND BOARDS LLC;
Assembly   LB680901_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;
PIN    11  = D0;

/* Address Decode and Chip Select outputs */
PIN    12  = !ROMCS;
PIN    13  = !IOCS;
PIN    14  = !MEMRD;
PIN	15  = LED;
PIN    16  = !RAMCS;
PIN    17  = LEDSTR;
PIN    18  = RDY;

ROMCS = CPUA15 & CPUA14 & CPUREAD;	/* 0xC000-0xFFFF	*/

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

IOCS = CPUA15 & !CPUA14 & CPUA13 &  CPUREAD		/* 0xA000-0xBFFF Serial (ACIA) */
#      CPUA15 & !CPUA14 & CPUA13 & !CPUREAD & VPB;	

RDY = VPB;

MEMRD = CPUREAD;

LEDSTR = CPUA15 & CPUA14 & !CPUREAD & VPB;	/* write to LED */

LED =  LEDSTR & D0
#      LED & !LEDSTR;

Backplane connector

Software

• LB-6809 code examples
• asm6809 - portable cross assembler targeting the Motorola 6809
  • Features arbitrarily complex expressions (with most C-style operators available), forward references, macro expansion and conditional assembly
  • Output formats are: Motorola SREC, Intel HEX (and others)
  • asm6809 Manual
  • Using asm6809 version 2.13
  • asm6809-2.13-w64 Local copy
• MC6809-MC6809E 8-Bit Microprocessor Programming Manual (M6809PM/AD) © Motorola Inc., 1981
• MC6809 Rference Card

Build 6809 Assembly Code (Windows 64-bit)

• Run asm6809 in Windows CMD prompt window

[path_to_asm6809.exe_program\]asm6809 loop.asm -H -l -o loop.hex

• -H option creates hex record file to download to programmer
• -l fileName option creates listing file
• -o filename option followed by output file name

Programming using TL866

• Set From File Start(Hex) to 0x0C000 when loading hex record file into TL866i Plus programmer

ROM access test code (loop.asm)

• Assemble loop.asm
  • my path below, YMMV

..\..\M6809_Assembler\asm6809-2.13-w64\asm6809 loop.asm -H -l loop.lst -o loop.hex

• Source code (loop.asm)

		ORG $C000
RESVEC	BRA	RESVEC
		ORG	$FFFE
LBFFE	FDB	RESVEC	         ; RESET 

• .hex file

:02C0000020FE20
:02FFFE00C00041
:00000001FF

LED Blink code (blink.asm)

• Added PLD code to make a trigger on pin 17 when EPROM address 0xC000-0xF000 is written
• Code doesn't use any RAM (CPU and EPROM only)
• LED is on U2-15 to GNS w/ 1.8K resistor
• Assemble blink.asm code
• See Rev 2 checkout notes for LED
  • my path below, YMMV

..\..\M6809_Assembler\asm6809-2.13-w64\asm6809 blink.asm -H -l blink.lst -o blink.hex

• Works, blinks LED at about 2 Hz
• Can use this as a SRAM test outout
  • Fast blink = Fail
  • Slow blink = Pass

SRAM Test (ramLoop.asm)

• ramLoop.asm - GitHub
• Loops on SRAM write/read on LB-6809-01 card
• Turn on LED if the test passes
• Turn off LED if the test fails
• Passes

SRAM Test (ramTest1.asm)

• ramTest1.asm - GitHub
• Write/read SRAM write/read single location on LB-MEM-02 card
• Blink LED slowly if the test passes
• Blink LED quickly if the test fails
• Passes

SRAM Test (ramTest.asm)

• ramTest.asm - GitHub
• Write/read SRAM write/read on all SRAM on LB-MEM-02 card
  • Test single location with 0x55/0xaa
  • Test all RAM with ramp
    • Tests all locations but repeats ever 256 bytes so addresses are not completely tested
  • Ramp upper 7 address lines with a ramp
• Blink LED slowly if the test passes
• Blink LED quickly if the test fails
• Test takes 0.6 secs
• Passes

ACIATest.asm

• AciaTest.asm
• Wrote code with Microsoft Pilot with minor modifications
• Required etch cut and added wire on LB-68B50-02 card
• Test with FTDI-49MM card
• 115,200 baud, No parity ,8 data bits, 1 stop bit
• Loops back data typed in
• Works

Microsoft Extended BASIC

• Based on Grant Searle's 6-chip 6809 computer which ports CoCo Extended BASIC
  • Microsoft Extended BASIC, as used in the Tandy Coco 2 (modified for the SBC with all I/O via serial
• MBasROM.hex
  • Hex file for 27C512
    • First three 16KB sections are filled with 0xFF
• 115,200 BAUD
• Same build as SIMPLE-6809 from Grant Searle
  • Grant wrote a serial handler to control the text I/O, along with suitable Control-C break handling
  • Includes commands from the "Extended" BASIC ROM (from the "Extended BASIC Unraveled II" book)
  • The ROM in the SBC is fully working with all the commands in the Standard and Extended ROMS that are applicable to the SBC
• BASIC from DB00 TO FFFF, so a large amount of free space suitable for a monitor etc (6912 bytes free)

• Works

6809 EXTENDED BASIC
(C) 1982 BY MICROSOFT

OK

• PuTTY settings

• Test software

10 FOR I =1 TO 10000
20 PRINT I
30 NEXT I

• Time ~49 secs

Reference Designs

• MP-09 MONITOR - SWTBUG SBUG monitor for the 6809
• SIMPLE-6809 Software - reference software that runs on SIMPLE-6809

Mechanicals

Rev 2

Checkout

Rev 3 PCB Changes

• Added LED to Y2-15
  • Silkscreen = STATUS
• Changed reset switch to right angle pushbutton switch
  • Can be pressed easier in the backplane
• Added bulk electrolytic capacitor

Rev 2 Checkout

• Built
• Worked with NOP Tester
• Got 8 MHz crystal
• E signal is 2 MHz- good
• Add LED that can be written under program control
  • Add wire U1-31 to U2-11 (D0)
  • Add LEDSTR when strobe write to 0xC000-0xFFFF (U2-17)
  • Add LED to U2-15 with 1.8K resistor
  • Write to 0xF000 to toggle the line
    • Bit D0
  • Running blink.asm code

Rev 2 PCB Changes from Rev 1

• Add U1-34 to U2-7 (VPB/E)
• Eliminate oscillator
  • Add 8 MHz crystal/caps
  • Cheaper and easier to find
• Add 4.7K pullup to U1-40 (ABORT*/HALT) line
• Change resistor values to lighten up Iol
• Beef up power plane connections to J1 and CPU/cap
• Move reset switch to the top of the board (where the oscillator used to be)

Rev 1 Checkout Notes

• Did not build
• Add wire U1-34 to U2-7 (VPB/E)
• Ground XTAL pin on CPU U1-39 (to U1-1 = GND)
• Use BOM for resistor values, not silkscreen
• Add 4.7K pullup to ABORT* line

Assembly Sheet

Rev 2

• Interactive BOM

Rev 1

• Use BOM for resistor values, not silkscreen
• Interactive BOM