Last updated 6/25/2024   0:26:22

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Dual 6502 Processor Project


Keith Sproul
EMail ksproul@skychariot.com

My first computer was the MOS Technologies KIM-1 Single Board Computer. This had a 6502 processor at 1mhz and 1 K or RAM. I did lots of programming on this computer, added Micro Technology Unlimited cards, and used it for years. I also got a Micro Unlimited MTU-130 computer which also used a 6502. I did some programing for MTU.
During the Christmas Break of 1980-1981, I made a dual processor computer with 2 1mhz 6502s running 180 degrees of each other. This made it so they were not accessing memory at the same time. These two processor shared memory and were able to talk to each other at full computer speed.

I now want to recreate this board. But the new one will have lots of memory and lots of I/O. It will be accessible via Ethernet. It will have an expansion bus compatible with the Planck 6502 system, and it will have the ability to use some Arduino Shields and Raspberry Pi Hats. I am going to do it in the following steps.

Table of Contents

Time Line
Project Info Websites
Memory Map
Program Model
I/O Port Mappings
Parts List for Dual Processor Board
Chip Inventory
Parts List for 6502 NOP Test Board
Parts List for UK101 Single Board Computer
Pictures
KIM-1 Computer
Keith's Dual 6502 Processor
6502 NOP Test Board
UK101 Single Board Computer
Planck 6502 Computer
68K-MBC: a 3 ICs 68008 Homebrew Computer
Reference Information
Keith's TCP/IP -- Serial Adapter Research
Raspberry Pi Hat Pinout
Arduino Shield Pinout
Arduino Mega Shield Pinout
Resistor Color Codes

Time Line and Steps to the Future

Description Date Comment
Got KIM-1 Computer 1977 My First Computer
Built original Dual 6502 Processor Board 1980-81 Christmas Break  
Decided to make new version of Dual Processor board 2023-03-01  
UK101 6502 Single Board Computer 2023-03-14 Ordered  
Gtek 7228 EPROM Programmer working 2023-03-17 Working with program on Linux
Software Development Assembler 2023-03-22 ca65 on Linux Working!
Software Development 'C' 2023-03-24 Started cc65 on Linux Partially Working
Software Development Forth    
Learn KiCad Circuit Design and PCB Layout Software 2023-03-20 Started LONG learning curve
First Board in KiCad is a Shield card for Arduino for Mark's Astronomy 2023-03-23 Started Good first step with KiCad
6502 NOP Test Board 2023-03-25 Ordered  
Planck 6502 Computer System 2023-03-27 Ordered  
6502 NOP Test Board 2023-03-30 Received Construction Started
UK101 6502 Single Board Computer 2023-03-30 Received Construction Started
NNZN-TCP232-E-I018 TCP/IP - Serial Convertor 2023-04-01 Received Broadcast Packets partialy working
Don't use this one
Got Clif's AIM-65 up and running 2023-04-01 AIM Forth works too
Got back work bench completely cleaned up and operational 2023-04-02  
Finished Nop6502 Board, tested all of my 6502's 5 out of 40+ failed 2023-04-06  
USR-TCP232-T2 TCP/IP - Serial Convertor 2023-04-06 Received Just Started
68k-MBC: 68008 Homebrew Computer 2023-04-18 Ordered  
USR-TCP232-302 TCP/IP - Serial Convertor 2023-04-21 GOT WORKING  
Planck 6502 Computer System 2023-04-22 Shipped from France  
HLK-RM04 TCP/IP - Serial Converter 2023-04-22 Received  
ECB 68k SBC 68008 CPU 2023-04-24 Ordered  
EPROM Emulator NG v2.2d 06/2022 2023-04-24 Ordered  
American Megatrends Qotom Q310p Mini PC (6 Serial Ports) 2023-04-24 Rcvd,got working Ubuntu Linux
68k-MBC: 68008 Homebrew Computer 2023-04-26 Received  
Got UK101 Running 2023-04-26 1983 65C02's running @ 2mhz!
Build Planck 6502 2023-04-28 Received 3 computer kits
Build Planck 6502 2023-05-01 Got Workign Running Forth Only
Build Planck 6502 2023-05-03 Got 2nd Conputer finished
Build Planck 6502 2023-05-04 Got 3rd Conputer finished
Working with Jonathan Foucher on wrting a Monitor program for Planck 2023-05-04 Lots of email
Planck 6502 Running 2023-05-10  
UK101 Downloading Intel & MOS Tech Paper Tape Formats and XModem 2023-05-10 XModem is NICE and fast
Get Planck Compact Flash Cards working with Forth 2023-05-18 CF Cards work great
Put Eproms with my Monitor code in both UK101s 2023-06-14  
Bought GTEK 7956 Gang Programmer 8 Slot 28 Pin EPROM 2024-06-25  
Get UK101 Running Interupt Driven Serial Port    
Get UK101 Running Forth    
Build 68k-MBC 68008    
Get 68k-MBC 68008 Running    
     
     
     
Modify Planck Serial Board to use Ethernet instead of USB    
Design Dual Processor Card using KiCad    

GOAL


Have Dual Processor Card Fully working in less than 2 years
This includes completely learning KiCad
Goal Date 2025-03-01
Back to Table of Contents

Project Info Sites

Decription Web Link
Lots of good information
www.6502.org LOTS AND LOTS OF GOOD STUFF
www.wilsonminesco.com wilsonminesco.com
Software
cc65 6502 C Compiler cc65.github.io
ca65 6502 Macro Assembler cc65.github.io/doc/ca65.html
cl65 6502 Linker cc65.github.io/doc/cl65.html
ld65 6502 Loader cc65.github.io/doc/ld65.html
Other 6602 C Compilers github.com/cc65/wiki/wiki/other-6502-C-compilers
Acme Cross Assembler for 6502 sourceforge.net/projects/acme-crossass/
DASM 6502 Assembler DASM 6502 Assembler
xa 6202 Assembler www.floodgap.com/retrotech/xa/
Compukit UK101 Simulator uk101.sourceforge.net
6502 Emulator written in ANSI 'C' github.com/redcode/6502
6502 Emulator written in C++ github.com/gianlucag/mos6502
6520 Emulator written in ARM Assembler Language github.com/BigEd/a6502
Forth on Planck 6502 (Tali Forth) www.hackster.io/....
Tali Forth 2 https://github.com/scotws/TaliForth2
6502 Secnd Forth github.com/dourish/secnd/
6502 Microsoft Basic Source Microsoft Basic for 6502
Enhanced 6502 Basic Source Enhanced 6502 Basic Source Code
Enhanced 68000 Basic Source Enhanced 68000 Basic Source Code
Making your own version of MS Basic www.pagetable.com/?p=46
KiCad, Free circuit and PCB Desogm CAD program www.kicad.org
KiCad 6502 Library github.com/Alarm-Siren/6502-Kicad-library
Hardware
Current 65C02 Documentation WDC 6502 Specs
65C02 Referece Manual www.zophar.net/fileuploads/2/10533qqcap/6502ref.html
UK101 6502 Board with Basic searle.x10host.com/uk101/uk101.html
Planck 6502 System planck6502.com
Jonathan Foucher's Planck 6502 site
(Cards for sale, but out of stock)
More Planck Info
68k-MBC: 68008 Homebrew Computer 68K-MBC Home Brew Computer
6502 NOP Test Board www.bygonebytes.co.uk/Acorn_revival.html#6502
Serial to Ethernet Adapter Ethernet to RS-232 Documentation
Serial to USB-C Adapter Serial to USB-C (ftdi)
XModem 6502 Source Code 6502.org/source/io/xmodem/xmodem.htm
SRecord, EPROM File Manipulation Program srecord.sourceforge.net
DB-25 Parallel Port Info Parallel Port Info
DE-9 Serial Port Info Serial Port Info
D-Subminature Standard D Connector Standard (Why DB-9 is WRONG, it is DE-9)
6502 Ethernet Solutions www.6502.org/users/andre/hwinfo/ethernet/
Grant Searle (designer of UK101) Gary Searle's Website
Flash Memory instead of EPROM DigiKey SST39SF020A-70-4C-PHE Flash Memory
Astron Power Supplies www.astroncorp.com
Astron Power Supply Repair Info www.repeater-builder.com
Other Sites of interest
Differences between 6502 and 65C02 wilsonminesco.com/NMOS-CMOSdif/
Arm Instruction Set ARM Instruction Set (PDF)
Linux Serial Port Programs Linux Serial Comm Methods
Linux Screen Quick Reference Guide aperiodic.net/screen/quick_reference
Linux Minicom program for serial communications Linux Minicom Program
How to Read/Write to a serial port in 'C' on Linux How to Program Serial I/O in 'C'
Serial Programming Guide for POSIX Operating Systems www.ing.iac.es//~docs/external/serial/serial.pdf
SRecord Linux program for manipulating EPROM files srecord.sourceforge.net/download.html
easyEda Online PCB Design easyeda.com
Bittle Turn-Key PCB Assembly Bittle Turn-Key PXV Assembly
Micro Technology Unlimited MTU-130 www.trailingedge.com/mtu130/
AIM-65 Users Guide AIM-65 Users Manual
AiM-65 RS-232 Interface cini.classiccmp.org/aim65/AIM-65%20RS232.pdf
I am using the items in Yellow
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MEMORY MAP

Same for both Processors

Start End Description Chip Comment
0000 0FFF 32K RAM 62256 32K Main System RAM
1000 1FFF
2000 2FFF
3000 3FFF
4000 4FFF
5000 5FFF
6000 6FFF
7000 7FFF
8000 BFFF 16K RAM 62256 32K Main System RAM Bank Switchable
Only half used: I/O pin is used to select which half
9000 9FFF
A000 AFFF
B000 BFFF
C000 CFFF 4K Shared RAM 6264 8K Both Processors see the same block or RAM
D000 D00F 6522 VIA Parallel Port #1 6522 2 Parallel Ports, Interval Interrupt Timmer
D010 D01F 6522 VUA Parallel Port #2 6522 2 Parallel Ports, Interval Interrupt Timmer
D020 D023 6551 ACIA Serial Port 6551  
D800 D8FF Planck I/O Card 0 n/a  
D900 D9FF Planck I/O Card 1 n/a  
DA00 DAFF Planck I/O Card 2 n/a  
DB00 DBFF Planck I/O Card 3 n/a  
DC00 DCFF Planck I/O Card 4 n/a  
DD00 DDFF Planck I/O Card 5 n/a  
DE00 DEFF Planck I/O Card 6 n/a  
DF00 DFFF Planck I/O Card 7 n/a  
E000 EFFF 8K EPROM 27512 (64K) Jumpers to Select 1 of 8 Banks
F000 FFFF
Larger than needed memory chips are used to keep parts inventory minimum
Back to Table of Contents

Program Model

Address SpaceDescription
0000 - 00FF 6502 Zero Page
0100 - 01FF 6502 Stack Space
0200 - 02FF Serial Port Input Buffer
0300 - 03FF Serial Port Output Buffer
0400 - 0FFF Variable Space
1000 - 7FFF 28K Main Memory: Program Space
8000 - BFFF 16K Main Memory: Bank Switchable
C000 - CFFF  4K Shared Memory
D000 - DFFF  4K I/O Space
E000 - FFFF  8K ROM
FFFA - FFFB NMI Vector
FFFC - FFFD Reset Vector
FFFE - FFFF IRQ/BRK Vector
Back to Table of Contents

I/O Ports

Chip Port Address Comment
6522 VIA #1 $D000 Port A Internal Control
Port B Available
6522 VIA #2 $D010
Pick one:  Arduino Shield
Raspberry Pi Hat
DB-25 connector for Centronics Printer Standard
6551 ACIA Serial Port $D020
Pick one:  Serial to Ethernet Adatper
Serial to USB Adapter
DE-9 Serial Connector, RS-232
Back to Table of Contents


VIA 6522 Registers
Address Name Description
$xx00 prb Port register B
$xx01 pra Port register A
$xx02 ddrb Data direction register B
$xx03 ddra Data direction register A
$xx04 t1_lo Timer 1, low byte
$xx05 t1_hi Timer 1, high byte
$xx06 t1l_lo Timer 1 latch, low byte
$xx07 t1l_hi Timer 1 latch, high byte
$xx08 t2_lo Timer 2, low byte
$xx09 t2_hi Timer 2, high byte
$xx0A sr Shift register
$xx0B acr Auxiliary control register
$xx0C pcr Peripheral control register
$xx0D ifr Interrupt flag register
$xx0E ier Interrupt enable register
$xx0F pra2 Port register A w/o handshake
ACIA 6551 Registers
$xx00 data Data register
$xx01 status Status register
$xx02 cmd Command register
$xx03 ctrl Control register
Back to Table of Contents

Parts List for Dual Processor Board

Yellow Background means optional
Blue Background means Possible Alternative
Qty Chip Description Comment In Stock
2 65C02 CPU / ProcessorLots
4 62256 32K RAM chip, 0000 - 7FFF, 8000 - BFFF 62256 Data Sheet 11
1 6264 8K Ram Chip, Shared C000 - CFFF 6264 Data Sheet 16
2 27512 64K EPROM With jumpers to select which 8K bank is being used (1 of 8)
For example, Basic in one ROM segment, and Forth in another segment
  Lots
  SST39F040 Flash Memory Chip, Possible replacement for EPROM    
4 6522 VIA (2) 8 bit bidirectional Parallel ports, Interval Timer 6522 Data Sheet 10
2 6551 ACIA Asynchronous Serial Interface Adapter 6551 Data Sheet
Experimenting With The 6551 ACIA
6
2 74LS138 3-Line to 8-Line Decoder/Demultiplexer 74LS138 Data Sheet  
2 74LS154 4-Line to 16-Line Decoder/Demultiplexer 74LS154 Data Sheet  
2 ATF22V10 Programmable Logic Device Programmable Logic Device Wiki
ATF22V10C Programming Algorithm
Programming PLDŐs with open source software
 
  ICE 40 FPGA, possible replacment for ATF22V10 www.latticesemi.com/iCE40  
2 NNZN-TCP232-E-I018 Ethernet to Serial Adapter Module TCP/IP to Serial Docs 5
2 USR-TCP232-T2 Ethernet to Serial Adapter Module TCP/IP to Serial Docs 3
2 MAX232 or DS1228 RS-232 Signal Level Convertor DS1228 Data Sheet 2 DS1228
2 DE-9 Connector Female, Right Angle PCB Mount Connector for Serial Interface Digi-Key Data Sheet 10
4 DB-25 Connector Male, Right Angle PCB Mount Connector for Paralell Interface
Centronics Standard Pinout
Digi-Key Data Sheet  
12 2x25 50 Pin Female Sockets Planck 6502 Expansion Bus    
Back to Table of Contents

Chip Inventory

Qty Chip Number Description Data Sheet
CPUs
30+ 6502 NMOS 1 Mhz CPU Date Code 1983 and others 6502 Wiki
4 6502 NMOS 1 Mhz CPU Date Code 1980? MOS Technologies 6502 Wiki
10 65C02 CMOS 1 Mhz CPU Date Code 1983/84 65C02 Wiki
14 6507 NMOS 1 Mhz CPU Date Code 1980 (8K Addressable 28 pin DIP) 6507 Wiki
2 6512 NMOS 1 mhz CPU (64K addressable 40 pin DIP) 6502 Wiki Variations and derivatives
I/O Chips
10 6522 VIA Paralell I/O Date Code 1980 6522 Wiki
9 6820 PIA Paralell I/O 6820 Wiki
4 6520 PIA Paralell I/O MOS Technologies 6820 Wiki
4 6532 RIOT RAM, I/O, Timer: 128 bytes RAM, Paralelle I/O, Timer PIA Wiki
1 6840 PTM Programable Timer 6840 Data Sheet
22 6264 Static Ram 8K  
13 2332 Static Ram 4K  
EPROMs
39 27512 EPROM 64K  
18 27256 EPROM 32K Used in UK101
? 27C256 EPROM 32K Used in UK101
7 27128 EPROM 16K  
9 2764 EPROM 8K  
30 2732 EPROM 4K  
15 2716 EPROM 2K  
6 Tubes 2708 EPROM 1K  
Misc Chips
Lots MC14506UBC Dual 2-Wide, 2-Input Expandable AND-OR-INVERT Gate MC14506UBC Data Shet
14 LM380N Low Power Audio Amplifier LM380N Data Sheet
5 MM74C906N Buffer, Non-Inverting 6 Element 1 Bit per Element Open Drain Output MM74C906N Data Sheet
3 S26LS31PC Quadruple Differential Line Driver S26LS31PC Data Sheet
25 CTS7309 Solid-State Driver Chip  
74C283 4-Bit Binary Full Adders With Fast Carry 74C283 Data Sheet
74367 Hex Bus Driver 3-State Outputs 74367 Data Sheet
74393 Dual 4-Bit Decade And Binary Counters 74393 Data Sheet
5 ICL7109CPI 12-Bit A/D Converter with 3-State Binary Outputs (40 pin DIP) ICL7109CPI Data Sheet
From Ebay
5 W65C02S8P-10 10 mhz  
2 65C02P2-12 12 mhz  
2 62256 32K RAM Used in UK101
2 28c256 32K EPPROM  
2 6850 ACIA Serial  
2 65C02P2-12 12 mhz  
2 74LS74    
1 74LS00    
2 74LS04    
 
11 62256 32K RAM Used in UK101
2 65C02P-10 10 mhz  
 
2 R6551AP ACIA Serial Chip For RS-232
Connectors
10 DE-9 F 9 Pin PCB mount Right Angle Female Used in UK101
10 DE-9 M 9 Pin PCB mount Right Angle Male  
Back to Table of Contents

Parts List for NOP 6502 Tester
Part # Description Qty In Stock
1 16 Pin Dip Switch 1 10+
2 2.1mm DC_POWER 2 20
3 Test Point Ring 28 100
4 HDR-M-2.54_2x4 1
5 Resistor SIL x8 4.7k ohms 3
6 HDR-M-2.54_1x1 1
7 Key 1 K4-6 6_TH 1
8 LED-TH-3mm_R 16
9 Zero Inserton Force Socket 40 pin 1 2
10 Crystal MCO-1510A 16 mhz 1 1
11 Resistor 4K7 4.7 k ohm 4
12 100n 1
13 10u Capacitor 1
14 74LS393 1
Back to Table of Contents

Parts List for UK101
Part # Description Qty In Stock
IC1 65C02-10 1 2
IC2 62256 1 2
IC3 27256 1 Lots
IC4 MAX232 1 1
IC5 6850 1 2
IC6 74LS04 1 2
IC7 74LS163 1
IC8 74LS74 1 2
IC9 74LS138 1
IC10 74LS00 1 1
IC11 74LS02 1
X1 4MHz crystal 1
C1-C5 1uF to 22uF 16V* 5
C6 470pF 1
R1 4k7 1
R2,R3 680R 2
Back to Table of Contents


Pictures


MOS Technologies KIM-1 Single Board Computer
My First Computer
1977



Keyboard / Display
Serial Port
Casset Interface for Program Storage


Keith Sproul's Original Dual Processor Board,
1980



Wire Wrap Side



6502 NOP Tester



www.bygonebytes.co.uk
NOP Card Frequency Chart


6502 NOP Tester, Bare Board



Keith's 6502 NOP Tester, Finished

2023-04-06

Works Great


UK-101 Finished



searle.x10host.com/uk101/uk101.html


UK-101 Bare Board



searle.x10host.com/uk101/uk101.html


Keith's 2 UK101 Computers



Planck 6502 Computer



planck6502.com


Planck 6502 Motherboard (1 of 2)



planck6502.com/Hardware/


Planck 6502 Motherboard (2 of 2)



planck6502.com/Hardware/


Keith's Planck Board



Planck 6502 Proto Board



planck6502.com/Hardware/proto/


Planck 6502 Serial Board



planck6502.com/Hardware/serial/


Planck 6502 Compact Flash Board



https://planck6502.com/Hardware/cf/


Planck 6502 Memory Bank Board



planck6502.com/Hardware/ram/


68K-MBC: a 3 ICs 68008 homebrew computer



https://hackaday.io/project/177988-68k-mbc-a-3-ics-68008-homebrew-computer


GTEK 7228 EPROM Programmer



GTEK 7956 Gang EPROM Programmer



Reference Informattion


Raspbery Pi Pinout



Arduino Shield Pinout



Arduina Mega Shield Pinout



Resistor Color Codes


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Created 3/19/2023
Modified 6/25/2024
© Copyright Keith Sproul
EMail ksproul@skychariot.com