SIMPLE-6802

Features

• 68B02 CPU
  • 1.8432 MHz clock
  • MC6802 is fully compatible with MC6800 but without messy two-phase clocking
• 32KB SRAM
• 16KB EPROM/EEPROM
  • 16KB reserved
  • 8KB (28C64 parts can be used)
• 68B50 Serial Port (ACIA)
  • RS-232 port
  • Header for FTDI
  • 115,200 baud
• Reset switch with optional Power Supervisor
• 95x95mm card
• (4) 6-32 mounting holes

Memory Map

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

Chipset

• 68B02P
• MC68B50CP
• HM62256BLP-7 32KB SRAM
• SST27SF256-70-3C-PGE EPROM

Design

• CPU

• EPROM

• SRAM

• ACIA

Headers / Connectors

J1 - RS-232 Serial

• DB-9 Male
• Pinout

1. N/C
2. Receive
3. Transmit
4. Loop to pin 6
5. GND
6. Loop to pin 4
7. RTS
8. N/C
9. N/C

J2 / J5 - EPROM/EEPROM Select Jumpers

• J2 - EPROM Pin 1 jumper
  • 1-2 for 28C64, 28C256 (Pull WE to VCC)
  • 2-3 for 27256, 27SF256, 27512 (Pull A14 to GND)
• J5 - EPROM Pin 27 jumper
  • GND (2-3)

EEPROM Pin Table

27512	27256	27SF256	28C256	27128	2764	28C64	PIN		PIN	2764	28C64	27128	28C256	27SF256	27256	27512
A15	VPP	VPP	A14	VPP	VPP	N/C	1		28	VCC	VCC	VCC	VCC	VCC	VCC	VCC
A12	A12	A12	A12	A12	A12	A12	2		27	PGM	WE*	PGM	WE*	A14	A14	A14
A7	A7	A7	A7	A7	A7	A7	3		26	A13	N/C	A13	A13	A13	A13	A13
A6	A6	A6	A6	A6	A6	A6	4		25	A8	A8	A8	A8	A8	A8	A8
A5	A5	A5	A5	A5	A5	A5	5		24	A9	A9	A9	A9	A9	A9	A9
A4	A4	A4	A4	A4	A4	A4	6		23	A11	A11	A11	A11	A11	A11	A11
A3	A3	A3	A3	A3	A3	A3	7		22	OE*	OE*	OE*	OE*	OE*	OE*	OE*
A2	A2	A2	A2	A2	A2	A2	8		21	A10	A10	A10	A10	A10	A10	A10
A1	A1	A1	A1	A1	A1	A1	9		20	CE*	CE*	CE*	CE*	CE*	CE*	CE*
A0	A0	A0	A0	A0	A0	A0	10		19	D7	D7	D7	D7	D7	D7	D7
D0	D0	D0	D0	D0	D0	D0	11		18	D6	D6	D6	D6	D6	D6	D6
D1	D1	D1	D1	D1	D1	D1	12		17	D5	D5	D5	D5	D5	D5	D5
D2	D2	D2	D2	D2	D2	D2	13		16	D4	D4	D4	D4	D4	D4	D4
GND	GND	GND	GND	GND	GND	GND	14		15	D3	D3	D3	D3	D3	D3	D3

J3 - FTDI / TTL Serial

• Requires a FTDI cross-over cable

1. GND
2. RTS* (out)
3. +5V
4. Receive (in)
5. Transmit (out)
6. N/C

J4 - 5V Power

• 2x4 header

First Unit Checkout

Install Sockets

• Machined pin sockets

Install Passives

Power

• Install 2x4 at J4
• Power card via J4 with 5V
• Check power pins on parts

Reset

• Install U7 Power Monitor
• Install pushbutton switch SW1
• Reset button gets stretched by Power Monitor U9
• Measure reset at 68B02 U5 pin 40

EPROM

• SST27C256 EEPROM
  • 32 KB part
  • Using first 16KB of EEPROM
  • J2 EEPROM pin 1 = VPP = VCC or GND
    • Jumper J2:2-3
  • J5 EEPROM pin 27 = A14 = GND
    • Jumper J5:2-3
• U1 - Do not install MAX232 yet
  • Use FTDI connector with FTDI-49MM card

EEPROM Programming

• Program using TL-866ii plus programmer
• File = SMITHBUG_FORTH_SIMPLE-FC.hex
• Part is 32 KB
• hex files is 16 KB

• Memory Buffer should look like

• Got Device ID error
• Turn off ID check

• Device programmed/verified

Test FTDI Serial

• Wiring is not 1:1 to FTDI-49MM
• Wire FTDI J3 to FTDI-49MM card
  • FTDI-49MM GND pin 1 to J3-1 RX on card
  • FTDI-49MM VCC pin 3 to J3-3 RX on card
  • FTDI-49MM TX pin 4 on to J3-5 RX on card
  • FTDI-49MM RX pin 5 on to J3-4 TX on card
  • FTDI-49MM CTS(in) pin 2 to J3-6 CTS on card

>J TO ADDR D000
Forth-68
1 2 + . 3  OK
  OK

Test RS-232 Serial

• With MAX232
• Install DB-9 Male
• Holes don't line up well, but 4-40 screws can fit
• Connected to FTDI-49MM and DCE cards
  • FTDI-49MM and DCE cards wired together
  • DCE has female DB-9
  • Separate power cable J2 on FTDI-49MM to J3 on card

• Built

• Works

Software

• 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

SmithBUG Builds for SIMPLE-MC6802 CPU Card

• Pre-built software
  • SMITHBUG 4KB build
  • SMITHBUG 8KB build
  • SMITHBUG 16KB 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

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

8KB Build

A68 SMITHBUG_SIMPLE-6802_E000.ASM -l SMITHBUG_SIMPLE-6802_E000.LST -s SMITHBUG_SIMPLE-6802_E000.S
srec_cat SMITHBUG_SIMPLE-6802_E000.s -offset - -minimum-addr SMITHBUG_SIMPLE-6802_E000.s -o smithbug_E000.hex -Intel

16KB Build

• Used with 27SF256 parts
  • 2nd half of EPROM unused

A68 SMITHBUG_SIMPLE-6802_C000.ASM -l SMITHBUG_SIMPLE-6802_C000.LST -s SMITHBUG_SIMPLE-6802_C000.S
srec_cat SMITHBUG_SIMPLE-6802_C000.s -offset - -minimum-addr SMITHBUG_SIMPLE-6802_C000.s -o smithbug_C000.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

• Corsham Tech FIG-Forth 68 page
• FIGFORTH GitHub
  • Enter command to srecord loader

&

• 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

• FIG-Forth-68 Commands
  • Type VLIST to get list og built-ins

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
  • 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

• TinyBASIC GitHub
• TINY BASIC User Manual
  • TINY BASIC User Manual PDF
• Load using &
  • Character/line delays 1 mSec
• Send TB_6800.s file
• Run using J 0100

References

• Deramp's STWPC page

Mechanicals

Assembly Sheet

SIMPLE-6802 Rev 1 Assembly Sheet