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Introduction to Commodore

8-Bit Maintenance

Rob Clarke

Bil Herd

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Goals

Determine the desired level of test and repair

Assess the target system

Quick appearance vs. Fully operational

Troubleshoot

Parts Swap vs. Full in depth

RepairParts availability, swap, hack

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Inspection

Look, look, look, look some more, seriously.

Initial Turn On

Watch, listen, smell, heat

The rap

Moving parts, oxidation, discoloration

Blown Fuse

About Fuses

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Anything Look Unusual

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Troubleshooting

Localization

Simple Example What it takes to light the indicator

AC

Cord Switch Fuse-

+

Power

Supply

Light

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Step One

Establish the Power Supplies are good

Logic Supply +5V

Analog Supply +12V, -12V

Adjunctive Supply 9VAC

Hi-Voltage CRT 18+ kV

Safety

Listen

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What Next

Supplies are good, now

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Diagnostic Hardware

PET Built in diagnostics on 2001

The PETvet

VIC-20

Commodore Diagnostic

C64 / C128

Dead Test Cartridge (Really Useful)

Other Diagnostic Cartridge Plus/4, C16, C232

Diag264

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PETvet

Developed By Mike Hill

Programmable ROM/RAM

replacement

Customisable Memory Maps

Reprogrammable by Serial port

Tools to halt CPU and view

memory

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Other PET Tools

Built in diagnostics on Rev-1 ROMs LED on board 2001 series

Build a NOP generator

The 2001 Service Kit!

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VIC-20 Diagnostic

RAM / ROM Checksums

Primarily for I/O

Loop Backs most ports

Picture Courtesy Ray Carlsen

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C64 / C128 Dead Test Cart

Ultimax mode to bypass Kernal

Works with no RAM/ROM/SID or CIAs

Uses border to indicate bad RAM

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C64 / C128 Diagnostic Cartridge Needs a bootable machine

Like VIC cart, loops back I/O ports

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C64 / C128 Diagnostic Cartridge Easy to build your own

Schematics freely available, but over complicated!

C128 Version similar but untested by me.

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Plus/4, C16, C232 Diag264

Built to fix a Commodore 232 Kernal or Cartridge based

Comprehensive testing of RAM/ROM & Ports

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Common Culprits VIC 20

Reliable, mine all work today with no fixes!

ROMs easily replaceable

RAMs easily sourceable (2114s, TMM2016)

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Common Culprits C64

64s are cheap, so by implication

Most commonly PLA (black screen)

& SID (works but defective sound) CIAs are fragile but replaceable

For everything else, Ray Carlsen

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SuperPLA Multi

Created by Jens Schoenfeld

Extracted C64 PLA eprom image in 1994

Equations derived as part of C-One project

Implemented on a MACH210 modern PLA Includes PLAs from CBM-IIs, Plus/4, and 1551

Also includes modes not implemented on C128

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Resources

PEThttp://www.bitfixer.com/bf/petvet

http://www.6502.org/users/andre/petindex/index.html

http://www.zimmers.net/anonftp/pub/cbm/pet/index.htmlhttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodore

VIC-20

http://sleepingelephant.com/ipw-web/bulletin/bb/index.php

C64, C128

http://www.retro-donald.de/pages/superpla-multi.php

http://www.swinkels.tvtom.pl/swinsid/http://www.lemon64.com/

http://personalpages.tds.net/~rcarlsen/

Plus/4, C16, C232

http://inchocks.co.uk/commodore/Diag264/HTMLManual/Diag264.htm

http://plus4world.powweb.com/homehttp://www.commodore16.com/index.php/forum.html

Spares

http://www.arcadecomponents.com/index.htmlhttp://store.go4retro.com/http://retro-donald.de/sinchai-shop/

General Info

http://www.softwolves.pp.se/misc/arkiv/http://personalpages.tds.net/~rcarlsen/http://www.zimmers.net/anonftp/pub/cbm/

http://www.bitfixer.com/bf/petvethttp://www.bitfixer.com/bf/petvethttp://www.6502.org/users/andre/petindex/index.htmlhttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.bitfixer.com/bf/petvethttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://www.bitfixer.com/bf/petvethttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.swinkels.tvtom.pl/swinsid/http://www.lemon64.com/http://personalpages.tds.net/~rcarlsen/http://www.bitfixer.com/bf/petvethttp://inchocks.co.uk/commodore/Diag264/HTMLManual/Diag264.htmhttp://www.commodore16.com/index.php/forum.htmlhttp://www.commodore16.com/index.php/forum.htmlhttp://www.commodore16.com/index.php/forum.htmlhttp://store.go4retro.com/http://www.arcadecomponents.com/index.htmlhttp://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://personalpages.tds.net/~rcarlsen/http://www.softwolves.pp.se/misc/arkiv/http://www.zimmers.net/anonftp/pub/cbm/http://www.zimmers.net/anonftp/pub/cbm/http://www.zimmers.net/anonftp/pub/cbm/http://www.zimmers.net/anonftp/pub/cbm/http://www.zimmers.net/anonftp/pub/cbm/http://personalpages.tds.net/~rcarlsen/http://personalpages.tds.net/~rcarlsen/http://www.softwolves.pp.se/misc/arkiv/http://www.softwolves.pp.se/misc/arkiv/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://retro-donald.de/sinchai-shop/http://store.go4retro.com/http://store.go4retro.com/http://store.go4retro.com/http://www.arcadecomponents.com/index.htmlhttp://www.commodore16.com/index.php/forum.htmlhttp://www.commodore16.com/index.php/forum.htmlhttp://www.commodore16.com/index.php/forum.htmlhttp://plus4world.powweb.com/homehttp://inchocks.co.uk/commodore/Diag264/HTMLManual/Diag264.htmhttp://inchocks.co.uk/commodore/Diag264/HTMLManual/Diag264.htmhttp://inchocks.co.uk/commodore/Diag264/HTMLManual/Diag264.htmhttp://www.bitfixer.com/bf/petvethttp://personalpages.tds.net/~rcarlsen/http://personalpages.tds.net/~rcarlsen/http://www.lemon64.com/http://www.lemon64.com/http://www.swinkels.tvtom.pl/swinsid/http://www.swinkels.tvtom.pl/swinsid/http://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.retro-donald.de/pages/superpla-multi.phphttp://www.bitfixer.com/bf/petvethttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://sleepingelephant.com/ipw-web/bulletin/bb/index.phphttp://www.bitfixer.com/bf/petvethttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.vintage-computer.com/vcforum/forumdisplay.php?21-Commodorehttp://www.zimmers.net/anonftp/pub/cbm/pet/index.htmlhttp://www.zimmers.net/anonftp/pub/cbm/pet/index.htmlhttp://www.6502.org/users/andre/petindex/index.htmlhttp://www.6502.org/users/andre/petindex/index.htmlhttp://www.bitfixer.com/bf/petvethttp://www.bitfixer.com/bf/petvethttp://www.bitfixer.com/bf/petvethttp://www.bitfixer.com/bf/petvet

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After Swapping the Chips

Check the environment carefully

Requires an Oscilloscope (or itd already be fixed)

Power Supply - most Common Denominator

Ripple and noise

Non-monotonic

Absolute values

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Power Supply

Non-monotonic power up

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Power Supply

Excessive ripple or other noise

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Care and Feeding of Proc

Proc

Clean +5v

Stable Clock

Clean /RST

A0-15

D0-7

/ROMsel

/CS Logic

R/W

$FFFC

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The Order of Things

/RESET

/ROM CS

/IO CS

/RAM CS

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Get to know the Neighbors

Proc

+5

Clock

/RESET

A0-15

D0-7

R/W/IRQ, /NMI

2 (Phi2)

Trigger

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RAM/ ROM

ROM

Trigger

ADDR DATA

/CE

RAM

Trigger

/CE

/WE

ADDR DATA

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Making Sense of Chaos

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When Logic is Invalid

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Zero or One

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Good Diagnostics

Problem with most microprocessor systems is

its an all or nothing affair.

A good diagnostic runs with minimal

requirements. First establishes RAM works

before using it for more advanced diagnostics.