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CHIP TROUBLESHOOTING GUIDE FOR THE COMMODORE C64 PROVIDED BY: DIGITAL.DOC WARNINGS! Disassemble, modify, or repair at your own risk! You will void the Warranty by opening the unit's case. Digital Doc accepts no responsibility for damaged components due to the following procedures. Follow all steps exactly as described. Procedures descibed require that power be applied to the unit while troubleshooting. Hazardous voltages may be present inside the unit while power is applied. If you are unsure of any step, or feel uncomfortable performing procedures described, have a qualified technician perform the disassembly and repair of your unit. COPYRIGHT NOTICE Copyright 1989 Robert W. Kucenski. Permission granted for free distribution provided full credit is given to the author. All other rights reserved. TABLE OF CONTENTS ----------------------------------------------------------------- Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 1 Disassembly Instructions . . . . . . . . . . . . . . . . . . . 2 Reassembly Instructions . . . . . . . . . . . . . . . . . . . 3 Using the Chip Troubleshooting Charts . . . . . . . . . . . . 4 Chip Troubleshooting Charts U1 - Complex Interface Adapter 1 . . . . . . . . . . . . 5 U2 - Complex Interface Adapter 2 . . . . . . . . . . . . 6 U3 - Basic Read Only Memory . . . . . . . . . . . . . . . 7 U4 - Kernal Read Only Memory . . . . . . . . . . . . . . 7 U5 - Character Read Only Memory . . . . . . . . . . . . . 8 U6 - Color Random Access Memory . . . . . . . . . . . . . 8 U7 - Microprocessor . . . . . . . . . . . . . . . . . . . 9 U8 - Hex Inverter . . . . . . . . . . . . . . . . . . . . 10 U9-U12 and U21-U24 - Dynamic Random Access Memory . . . . 10 U13 - Quad Dual Input Multiplexor . . . . . . . . . . . . 11 U14 - Quad Dual Input Multiplexor . . . . . . . . . . . . 11 U15 - 2-4 Decoder . . . . . . . . . . . . . . . . . . . . 12 U16 - Quad Bilateral Switch . . . . . . . . . . . . . . . 12 U17 - Programmable Logic Array . . . . . . . . . . . . . 13 U18 - Sound Interface Device . . . . . . . . . . . . . . 14 U19 - Video Interface Chip . . . . . . . . . . . . . . . 15 U20 - Dual Timer . . . . . . . . . . . . . . . . . . . . 16 U25 - Quad Dual Input Multiplexor . . . . . . . . . . . . 16 U26 - Octal D Type Latch . . . . . . . . . . . . . . . . 17 U27 - Quad 2-Input And Gate . . . . . . . . . . . . . . . 17 U28 - Quad Bilateral Switch . . . . . . . . . . . . . . . 18 U29 - Dual D Flip-Flop . . . . . . . . . . . . . . . . . 18 U30 - 2-4 Decoder . . . . . . . . . . . . . . . . . . . . 18 U31 - Dual Voltage Controlled Oscillator . . . . . . . . 19 U32 - Phase Frequency Detector and Charge Pump . . . . . 19 Chip Location Chart . . . . . . . . . . . . . . . . . . . . . 20 INTRODUCTION This guide is not designed to teach you everything there is to know about troubleshooting and repairing the Commodore C64. Instead, it is intended to provide information to assist you in locating problems to a chip level. In addition, using the information presented here will give you a head start in helping me troubleshoot your problem through the GEnie Clinic in the Bulletin Board (See Catagory 11). Every effort has been made to ensure the accuracy of the information presented here. However, errors do have a habit of creeping in. Feel free to send comments, corrections, etc to my E-Mail address: Digital.Doc on GEnie. Happy Computing! <Doc> Page 1 DISASSEMBLY INSTRUCTIONS ******************************************************* * WARNING * * * * Follow all directions and warnings. Failure to do * * so could cause equipment damage or personel injury! * ******************************************************* Step 1: Turn off the electrical power to the unit and any peripheral equipments that are attached. Unplug the C64 power supply from the electrical outlet. Step 2: Disconnect all cartridges, modems, interfaces, and all cables from the C64. Step 3: Turn the C64 upside down so the front of the keyboard faces you. Step 4: Locate and remove the three screws at the front of the case. Step 5: Holding the case halves together, turn the unit rightside up with the front of the keyboard facing you. Step 6: Gently lift the top half of the case up and away from you. Step 7: Disconnect the small connector on the front right side of the circuit board. Step 8: Disconnect the large connector on the back left side of the circuit board. Step 9: Remove the top half of the case containing the keyboard. Step 10: Turn the bottom half of the case containing the circuit board so that the back side faces you. Step 11: On the left side, locate the thin piece of metal tape which connects the aluminized cardboard shield to the RF modulator shield. Step 12: Using extreme caution, unsolder this piece of tape from the RF modulator shield. Step 13: Turn the unit around so the front faces you and lift the aluminized cardboard shield toward you. You should now have free access to the circuit board and all the components. Page 2 ASSEMBLY INSTRUCTIONS ******************************************************* * WARNING * * * * Follow all directions and warnings. Failure to do * * so could cause equipment damage or personel injury! * ******************************************************* Step 1: Place the unit so the front faces you and fold the aluminized cardboard shield away and down until it covers the circuit board. Step 2: Turn the bottom half of the case containing the circuit board so that the back side faces you. Step 3: On the left side, locate the thin piece of metal tape was unsoldered during disassembly Step 4: Using extreme caution, solder this piece of tape to the RF modulator shield. Step 5: Turn the unit so the front faces you. Step 6: Align the top half of the case containing the keyboard with the back of the bottom half of the case ensuring the tabs on the top line up with the slots on the bottom. Step 7: Reconnect the large connector on the back left side of the circuit board. NOTE: The white wire running to the connector should be toward the front of the unit. Step 8: Reconnect the small connector on the front right side of the circuit board. NOTE: The red wire running to the connector should be forward. Step 9: Gently close the case halves together ensuring that the tab from the top half are properly seated in the slots in the bottom half. Step 10: Holding the case halves together, turn the unit upside down with the front of the keyboard facing you. Step 11: Locate and replace the three screws at the front of the case. Step 12: Turn the C64 right side up. Step 13: Reconnect all cartridges, modems, interfaces, and all cables to the C64. Page 3 USE OF THE CHIP TROUBLESHOOTING CHART ******************************************************* * WARNING * * * * Be EXTREMELY careful when making measurements that * * you do not short two pins together! At the least, * * this will require that the unit be powered down and * * then back up to continue testing. It is also * * possible to damage the chips under test! * ******************************************************* 1. All of the signals listed in the charts that follow were obtained using an inexpensive Micronta Digital Logic Probe available from Radio Shack as their catalog number 22-303. The signals should appear the same with any other logic probe you might have available. 2. Measurements were all taken with all cartridges, interfaces, etc disconnected. You may leave the monitor/TV connected. 3. All measurements are taken after power up with the screen showing the normal power up display and a blinking cursor. If you do not get the normal power up screen, then continue anyway. Your measurement may lead you to the problem. 4. Power leads for the logic probe should be connected as follows: Connect the black (negative) lead to the screw above and to the right of C92. Connect the red (positive) lead to the left lead from C92. Warning: Make all connections with the power off and the power cord to the C64 disconnected. Screw (+) : R : I ( ) : G : H C92 ===== : T : - : : : : CN : : : 10 : : : - : : Screw (+) : : -------------- FRONT 5. Set the normal/pulse switch to the pulse position. This is the position the switch will remain in throughout measurements. Unless otherwise noted on the diagram all chips are the TTL variety. Unless the chart specifically notes the chip as a CMOS chip, the CMOS/TTL switch should be in the TTL position. Set this switch to the CMOS position when making measurements on a chip designated as a CMOS. Page 4 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Low (Ground) ---1: - :40-- High : : Pulse (H) ---2: :39-- High : : Pulse (H) ---3: U1 :38-- Pulse : : Pulse (H) ---4: :37-- Pulse : : Pulse (H) ---5:Complex :36-- Pulse : : Pulse (H) ---6:Interface:35-- Pulse : : Pulse (H) ---7:Adapter 1:34-- High : : Pulse (H) ---8: :33-- Pulse : : Low ---9: 6526 :32-- Pulse : : High --10: :31-- Pulse : : High --11: :30-- Pulse : : High --12: :29-- Pulse : : High --13: :28-- Pulse : : High --14: :27-- Pulse : : High --15: :26-- Pulse : : High --16: :25-- Pulse : : High --17: :24-- High : : Pulse (H) --18: :23-- Pulse (H) : : Pulse --19: :22-- Pulse : : High (+5 VDC) --20: :21-- Pulse (H) :---------: NOTES: 1. This is a CMOS chip. Page 5 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Low (Ground) ---1: - :40-- High : : High ---2: :39-- High : : High ---3: U2 :38-- Pulse : : High ---4: :37-- Pulse : : Low ---5:Complex :36-- Pulse : : High ---6:Interface:35-- Pulse : : Low ---7:Adapter 2:34-- High : : Low ---8: :33-- Pulse : : High ---9: 6526 :32-- Pulse : : High --10: :31-- Pulse : : High --11: :30-- Pulse : : High --12: :29-- Pulse : : High --13: :28-- Pulse : : High --14: :27-- Pulse : : High --15: :26-- Pulse : : High --16: :25-- Pulse : : High --17: :24-- High : : Pulse (H) --18: :23-- High : : Pulse --19: :22-- Pulse : : High (+5 VDC) --20: :21-- High :---------: NOTES: 1. This is a CMOS chip. Page 6 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :24-- High (+5 VDC) : : Pulse ---2: :23-- Pulse : : Pulse ---3: U3 :22-- Pulse (L) : : Pulse ---4: :21-- Pulse : : Pulse ---5: Basic :20-- High : : Pulse ---6: Read :19-- Pulse : : Pulse ---7: Only :18-- Pulse (L) : : Pulse ---8: Memory :17-- Pulse : : Pulse ---9: 2364 :16-- Pulse : : Pulse --10: :15-- Pulse : : Pulse --11: :14-- Pulse (L) : : Low (Ground) --12: :13-- Pulse (L) :---------: :--- ---: Pulse ---1: - :24-- High (+5 VDC) : : Pulse ---2: :23-- Pulse : : Pulse (L) ---3: U4 :22-- Pulse (L) : : Pulse ---4: :21-- Pulse : : Pulse (L) ---5: Kernal :20-- PUlse : : Pulse ---6: Read :19-- Pulse : : Pulse ---7: Only :18-- Pulse (L) : : Pulse (L) ---8: Memory :17-- Pulse : : Pulse (L) ---9: 2364 :16-- Pulse : : Pulse (L) --10: :15-- Pulse : : Pulse --11: :14-- Pulse (L) : : Low (Ground) --12: :13-- Pulse (L) :---------: Page 7 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :24-- High (+5 VDC) : : Pulse ---2: :23-- Pulse : : Pulse (L) ---3: U5 :22-- Pulse (L) : : Pulse ---4: :21-- High : : Pulse (L) ---5:Character:20-- Pulse : : Pulse ---6: Read :19-- Pulse : : Pulse ---7: Only :18-- Pulse (L) : : Pulse ---8: Memory :17-- Pulse : : Pulse (L) ---9: 2332 :16-- Pulse : : Pulse (L) --10: :15-- Pulse : : Pulse --11: :14-- Pulse (L) : : Low (Ground) --12: :13-- Pulse (L) :---------: :--- ---: Pulse ---1: - :18-- High (+5 VDC) : : Pulse ---2: :17-- Pulse : : Pulse ---3: U6 :16-- Pulse : : Pulse ---4: :15-- Pulse : : Pulse ---5: Color :14-- Pulse : : Pulse ---6: Random :13-- Pulse : : Pulse ---7: Access :12-- Pulse : : Pulse ---8: Memory :11-- Pulse : : Low (Ground) ---9: 2114 :10-- Pulse (H) :---------: Page 8 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :40-- High : : Pulse (H) ---2: :39-- Pulse : : Pulse (H) ---3: U7 :38-- Pulse (H) : : High ---4: :37-- Pulse : : Pulse ---5: Micro- :36-- Pulse : : High (+5 VDC) ---6:Processor:35-- Pulse : : Pulse ---7: :34-- Pulse : : Pulse ---8: :33-- Pulse : : Pulse ---9: 6510 :32-- Pulse : : Pulse --10: :31-- Pulse : : Pulse --11: :30-- Pulse : : Pulse --12: :29-- High : : Pulse --13: :28-- High : : Pulse --14: :27-- High : : Pulse --15: :26-- Low : : Pulse --16: :25-- High : : Pulse --17: :24-- No Light : : Pulse --18: :23-- Pulse (H) : : Pulse --19: :22-- Pulse (H) : : Pulse --20: :21-- Low (Ground) :---------: NOTES: 1. This is a CMOS chip. Page 9 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Low ---1: - :14-- High (+5 VDC) : : High ---2: :13-- Low : : Pulse ---3: U8 :12-- High : : Pulse ---4: Hex :11-- High : : Low ---5:Inverter :10-- Low : : High ---6: 7406 :9--- Low : : Low (Ground) ---7: :8--- High :---------: :--- ---: No Light ---1: - :16-- Low (Ground) : : Pulse ---2: U9-12 :15-- Pulse : : Pulse ---3: U21-24 :14-- Pulse : : Pulse ---4: Dynamic :13-- Pulse : : Pulse ---5: Random :12-- Pulse : Access : Pulse ---6: Memory :11-- Pulse : : Pulse ---7: 4164-2 :10-- Pulse : : +5 VDC ---8: :9--- Pulse :---------: Page 10 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :16-- High (+5 VDC) : : Pulse ---2: :15-- Pulse : : Pulse ---3: U13 :14-- Pulse : : Pulse ---4: Quad :13-- Pulse : : Pulse ---5: Dual :12-- Pulse : Input : Pulse ---6: Multi- :11-- Pulse : plexor : Pulse ---7: :10-- Pulse : 74LS257 : Low (Ground) ---8: :9--- Pulse :---------: :--- ---: Pulse ---1: - :16-- High (+5 VDC) : : High ---2: :15-- Pulse : : Pulse ---3: U14 :14-- Pulse (H) : : Pulse ---4: Quad :13-- Pulse (H) : : High ---5: Dual :12-- Pulse : Input : Pulse ---6: Multi- :11-- Pulse : plexor : Pulse ---7: :10-- Pulse : 74LS258 : Low (Ground) ---8: :9--- Pulse :---------: Page 11 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse(H) ---1: - :16-- High (+5 VDC) : : Pulse ---2: :15-- Pulse (H) : : Pulse ---3: U15 :14-- Pulse : : High ---4: 2-4 :13-- Pulse : : High ---5: Decoder :12-- Pulse (H) : : Slow Pulse (H) ---6: :11-- High : : Pulse (H) ---7: :10-- High : 74LS139 : Low (Ground) ---8: :9--- High :---------: :--- ---: Pulse ---1: - :14-- High (+5 VDC) : : Pulse ---2: :13-- Pulse : : Pulse ---3: U16 :12-- Pulse : : Pulse ---4: Quad :11-- Pulse : : Pulse ---5: Bi- :10-- Pulse : Lateral : Pulse ---6: Switch :9--- Pulse : : Low (Ground) ---7: 4066 :8--- Pulse :---------: Page 12 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Low ---1: - :28-- High (+ 5 VDC) : : Pulse (H) ---2: :27-- Pulse : : Pulse (H) ---3: U17 :26-- Pulse (H) : : Pulse (H) ---4:Program- :25-- Pulse : able : High ---5: Logic :24-- Pulse (H) : Array : High ---6: :23-- High : : High ---7: :22-- High : 82S100 : High ---8: :21-- Pulse : : Pulse ---9: :20-- Pulse : : High --10: :19-- Ground : : High --11: :18-- Pulse : : Pulse (H) --12: :17-- High : : Pulse (H) --13: :16-- Pulse : : Low (Ground) --14: :15-- Pulse :---------: NOTES: 1. This is a CMOS chip. Page 13 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: High ---1: - :28-- (+ 12 VDC) : : High ---2: :27-- High : : High ---3: U18 :26-- High : : High ---4: Sound :25-- High (+ 5 VDC) :Interface: High ---5: Device :24-- Pulse (L) : : Pulse ---6: :23-- Pulse (L) : : Pulse ---7: :22-- Pulse : 6581 : High ---8: :21-- Pulse : : Pulse ---9: :20-- Pulse : : Pulse --10: :19-- Pulse : : Pulse --11: :18-- Pulse : : Pulse --12: :17-- Pulse : : Pulse --13: :16-- Pulse : : Low (Ground) --14: :15-- Pulse :---------: NOTES: 1. This is a CMOS chip. 2. WARNING: Don't probe pin 28 with a logic probe! Page 14 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :40-- High (+ 5 VDC) : : Pulse ---2: :39-- Pulse : : Pulse ---3: U19 :38-- Pulse : : Pulse ---4: :37-- Pulse : : Pulse ---5: Video :36-- Pulse : : Pulse ---6:Interface:35-- Pulse : : Pulse ---7: Chip :34-- Pulse : : Pulse (H) ---8: :33-- Pulse : : High ---9: 6567 :32-- Pulse : : High --10: :31-- Pulse : : Pulse (H) --11: :30-- Pulse (H) : : Pulse (H) --12: :29-- Pulse : : (+ 12 VDC) --13: :28-- Pulse : : -[--14: :27-- Pulse Video Output -: : : -[--15: :26-- Pulse : : Pulse --16: :25-- Pulse : : Pulse --17: :24-- Pulse : : Pulse --18: :23-- Pulse : : Pulse --19: :22-- Pulse : : Low (Ground) --20: :21-- Pulse :---------: NOTES: 1. This is a CMOS chip. 2. WARNING: Don't probe pins 13, 14, or 15 with a logic probe. Page 15 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Low ---1: - :14-- High (+ 5 VDC) : : Low ---2: :13-- Low : : High ---3: U20 :12-- Low : : High (+ 5 VDC) ---4: Dual :11-- High : Timer : Low ---5: :10-- High (+ 5 VDC) : : High ---6: 556 :9--- Low : : Low (Ground) ---7: :8--- High :---------: :--- ---: Pulse ---1: - :16-- High (+5 VDC) : : Pulse ---2: :15-- Pulse : : Pulse ---3: U25 :14-- Pulse : : Pulse ---4: Quad :13-- Pulse : : Pulse ---5: Dual :12-- Pulse : Input : Pulse ---6: Multi- :11-- Pulse : plexor : Pulse ---7: :10-- Pulse : 74LS257 : Low (Ground) ---8: :9--- Pulse :---------: Page 16 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: Pulse ---1: - :20-- +5 VDC : : Pulse ---2: :19-- Pulse Low : : Pulse ---3: U26 :18-- Pulse Low : : Pulse ---4: Octal :17-- Pulse : : Pulse ---5: D Type :16-- Pulse : Latch : Pulse ---6: :15-- Pulse Low : : Pulse ---7: :14-- Pulse Low : 74LS373 : Pulse ---8: :13-- Pulse Low : : Pulse ---9: :12-- Pulse : : Ground --10: :11-- Pulse Low :---------: :--- ---: High ---1: - :14-- +5 VDC : : Pulse ---2: :13-- High : : Pulse ---3: U27 :12-- Pulse : : Pulse ---4: Quad :11-- Pulse : 2-Input : High ---5: And :10-- High : Gate : Pulse ---6: :9--- Pulse : : Ground ---7: 74LS08 :14-- Pulse :---------: Page 17 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: No Light ---1: - :14-- High (+5 VDC) : : Pulse (L) ---2: :13-- Low : : Pulse (L) ---3: U28 :12-- Pulse (H) : : (See Note 1) ---4: Quad :11-- Pulse (L) : : Low ---5: Bi- :10-- Pulse (L) : Lateral : Pulse (H) ---6: Switch :9--- Pulse (L) : : Low (Ground) ---7: 4066 :8--- Pulse (L) :---------: :--- ---: Low ---1: - :14-- High (+5 VDC) : : Low ---2: :13-- High : : Low ---3: U29 :12-- Pulse : : Low ---4: Dual :11-- Pulse : D : High ---5:Flip-Flop:10-- High : : High ---6: :9--- Pulse : : Low (Ground) ---7: 74LS74 :8--- Pulse :---------: :--- ---: Low ---1: - :16-- High (+5 VDC) : : Pulse ---2: :15-- High : : Pulse ---3: U30 :14-- Low : : High ---4: 2-4 :13-- High : Decoder : Pulse ---5: :12-- Pulse : : Pulse ---6: :11-- Pulse : : High ---7: 74LS193 :10-- Low : : Low (Ground) ---8: :9--- High :---------: NOTES: 1. Pin 4 of U28 lights the Pulse light, but neither the High or Low lights. Page 18 COMMODORE C64 CHIP TROUBLESHOOTING CHART ----------------------------------------------------------------- :--- ---: No Light ---1: - :16-- High (+5 VDC) : : No Light ---2: :15-- High (+5 VDC) : : Low ---3: U31 :14-- Low (Ground) : : No Light ---4: Dual :13-- No Light : Voltage : No Light ---5:Control'd:12-- No Light : OSC : Low (Ground) ---6: :11-- Low (Ground) : : Pulse ---7: 74LS629 :10-- Pulse : : Low (Ground) ---8: :9--- Low (Ground) :---------: :--- ---: Pulse ---1: - :14-- High (+5 VDC) : U32 : Pulse (H) ---2: Phase :13-- High :Frequency: Pulse ---3:Detector :12-- High : And : High ---4: Charge :11-- Pulse (H) : Pump : Pulse ---5: :10-- Pulse (L) : : Pulse ---6: :9--- No Light : : Low (Ground) ---7: MC4044 :8--- No Light :---------: NOTES: 1. These two chips are not really digital devices; however, a logic probe can be used to make a quick check of their operation. Page 19 Ç COMMODORE 64 CHIP LOCATION CHART Presented by: Digital Doc 7 1 7 1 20 1 ------- ------- -------------------- : U20 : : U8 : : U1 : : ( : ( : : : 556 : : 7406: : 6526 ( ------- ------- : : 8 14 8 14 : CIA1 : -------------------- 21 40 8 1 8 1 -------- -------- 20 1 : U21 : : U9 : -------------------- : RAM ( : RAM ( : U2 : :4164-2: :4164-2: : : -------- -------- : 6526 ( 9 16 9 16 : : : CIA2 : 8 1 8 1 -------------------- -------- -------- 21 40 : U22 : : U10 : : RAM ( : RAM ( :4164-2: :4164-2: -------- -------- 9 16 9 16 8 1 8 1 12 1 -------- -------- ------------ : U23 : : U11 : : U3 : : RAM ( : RAM ( : : :4164-2: :4164-2: : 2364 ( -------- -------- : : 9 16 9 16 :BASIC ROM : ------------ 8 1 8 1 13 24 -------- -------- : U24 : : U12 : : RAM ( : RAM ( :4164-2: :4164-2: 12 1 -------- -------- ------------ 9 16 9 16 : U4 : : : 8 1 8 1 : 2364 ( -------- -------- : : : U25 : : U13 : :KERNAL ROM: : ( : ( ------------ :LS257 : :LS257 : 13 24 -------- -------- 9 16 9 16 10 1 8 1 12 1 ---------- -------- ------------ : U26 : : U15 : : U5 : : ( : ( : : :LS373 : : LS139: : 2332 ( ---------- -------- : : 11 20 9 16 :CHAR ROM : ------------ 13 24 8 1 7 1 -------- ------- : U14 : : U27 : : ( : ( 20 1 :LS258 : :LS08 : -------------------- -------- ------- : U7 : 9 16 8 14 : : : 6510 ( : : 7 1 9 1 : MICROPROCESSOR : ------- --------- -------------------- : U16 : : U6 : 21 40 : ( :COLOR ( :4066 : : 2114 : ------- --------- 8 14 10 18 7 1 14 1 14 1 ------- -------------- -------------- : U28 : : U18 : : U17 : : ( : : : : :4066 : : 6581 ( : 825100 ( ------- : : :PROGRAMMABLE: 8 14 : SID : :LOGIC ARRAY: -------------- -------------- 15 28 15 28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1 . . . . -------------------- . . . . : U19 : . . . . : : . . . . : 6567 ( . . . . :VIDEO INTERFACE : . . . . : CHIP : . . RF . . -------------------- . . Modulator . . 21 40 . . . . . . . . 8 1 7 1 . . . . -------- ------- . . . . : U31 : : U29 : . . . . : ( : ( . . . . :LS629 : : LS74: . . . . . . . . . . . . -------- ------- . . 9 16 8 14 . . . . 8 1 . . -------- . . : U30 : . . : ( . . : LS193: . . -------- . . 9 16 . . . . 7 1 . . ------- . . : U32 : . . : ( . . :4044 : . . ------- . . 8 14 . . . . . . . . . . . . . . . IN +21------ 1---: : 3---:7812: 2---: : +12------ OUT ------- : : :7805 : : : ------- : : : : : : : : : 1 3 2 +12 +5 IN OUT Ç