Commodore 64 Tester using MCL64

I developed a tester for the Commodore 64 using the MCL64 which allows the user to replace the computer’s MOS6510 with the MCL64 board and run an extensive set of tests on the motherboard. The system generates the 6510 bus cycles to allow it to access all of the C64’s components the same way the original CPU does while communicating with the user via the Serial Console built into the Teensy 4.1!

Some more information on the MCL64 hardware is here: https://microcorelabs.wordpress.com/2021/04/16/mcl64-mos-6510-emulator-works-in-commodore-64/

The idea was to leverage the ability to write tests in simple C code to quickly debug and isolate motherboard faults on the Commodore 64. Other test programs for the C64 like Dead Test are usually written in 6502 assembly so difficult to maintain and extend, are not very large or extensive, and rely on the CPU to be functional to run them. This MCL64-based tester requires only power and clocks to be working for it to be able to generate bus cycles and begin testing components.

There are around fifty tests which include an isolated test for the PLA, extensive checks of individual address and data signals, DRAM and Color RAM storage ability, ROM contents, and VIC-II and SID register accesses. It should at least allow the user to diagnose and fix a non-booting Commodore 64.

The hope is that these tests can be used to quickly and easily identify faulty components on the vintage Commodore 64 machines.

The source code on GitHub: https://github.com/MicroCoreLabs/Projects/tree/master/MCL64_Tester

Here is a Serial Terminal capture of the tests:

MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF



Probe the Cartridge Port Edge Connector, pin 2 and 3 to verify 5 volts DC
Probe the User Port Edge Connector, pin 10 and 11 to verify 9 volts **AC**
Probe the VIC-II, pin 13 to verify 12 volts DC
Probe the CPU, pin 1 to verify the 1Mhz clock input from the VIC-II. -- If using volt-meter you should measure around 1.6V-DC
Probe the CPU, pin 39 to verify the 1Mhz clock output. -- If using volt-meter you should measure around 1.6V-DC


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF





Running some initial tests of the motherboard IC's:


64KB DRAM..........PASSED
KERNAL ROM.........PASSED
BASIC ROM..........PASSED
CHARACTER ROM......PASSED
Color RAM..........PASSED
VIC-II Registers...PASSED
VIC-II - Setting screen background to BLUE 
SID - Playing a note for one second 


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF




PLA Output Toggling Test Menu
Will toggle just the selected outputs
-------------------------------------
0) PLA Pin-18                             CASRAM due to VIC-II activity only
1) PLA Pin-18                             CASRAM due to VIC-II and CPU activity
2) PLA Pin-17                             BASIC  ROM with PLA inputs [CHARGEN=1, HIRAM=1, LORAM=1]
3) PLA Pin-17                             BASIC  ROM with PLA inputs [CHARGEN=0, HIRAM=1, LORAM=1]
4) PLA Pin-16                             KERNAL ROM with PLA inputs [CHARGEN=1, HIRAM=1, LORAM=1]
5) PLA Pin-16                             KERNAL ROM with PLA inputs [CHARGEN=1, HIRAM=1, LORAM=0]
6) PLA Pin-16                             KERNAL ROM with PLA inputs [CHARGEN=0, HIRAM=1, LORAM=1]
7) PLA Pin-16                             KERNAL ROM with PLA inputs [CHARGEN=0, HIRAM=1, LORAM=0]
8) PLA Pin-15                             CHARACTER ROM
9) PLA Pin-12 & U15 Pin-4                 VIC-II 
a) PLA Pin-12 & U15 Pin-5                 SID 
b) PLA Pin-12 & U15 Pin-7 & U15 Pin-12    CIA U1 
c) PLA Pin-12 & U15 Pin-7 & U15 Pin-11    CIA U2 

d) PLA Pin-13 & U15 Pin-6                !!! Color RAM Write Enable and Chip Select !!! Infinite loop, so will need to reset the board to exit !!!  
x) Exit to Main Menu 



MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF

KERNAL ROM Tests
----------------
Dumping KERNAL ROM:
85 56 20 F BC A5 61 C9 88 90 3 20 D4 BA 20 CC BC A5 7 18 69 81 F0 F3 38 E9 1 48 A2 5 B5 69 B4 61 95 61 94 69 CA 10 F5 A5 56 85 70 20 53 B8 20 B4 BF A9 C4 A0 BF 20 59 E0 A9 0 85 6F 68 20 B9 BA 60 85 71 84 72 20 CA BB A9 57 20 28 BA 20 5D E0 A9 57 A0 0 4C 28 BA 85 71 84 72 20 C7 BB B1 71 85 67 A4 71 C8 98 D0 2 E6 72 85 71 A4 72 20 28 BA A5 71 A4 72 18 69 5 90 1 C8 85 71 84 72 20 67 B8 A9 5C A0 0 C6 67 D0 E4 60 98 35 44 7A 0 68 28 B1 46 0 20 2B BC 30 37 D0 20 20 F3 FF 86 22 84 23 A0 4 B1 22 85 62 C8 B1 22 85 64 A0 8 B1 22 85 63 C8 B1 22 85 65 4C E3 E0 A9 8B A0 0 20 A2 BB A9 8D A0 E0 20 28 BA A9 92 A0 E0 20 67 B8 A6 65 A5 62 85 65 86 62 A6 63 A5 64 85 63 86 64 A9 0 85 66 A5 61 85 70 A9 80 85 61 20 D7 B8 A2 8B A0 0 4C D4 BB C9 F0 D0 7 84 38 86 37 4C 63 A6 AA D0 2 A2 1E 4C 37 A4 20 D2 FF B0 E8 60 20 CF FF B0 E2 60 20 AD E4 B0 DC 60 20 C6 FF B0 D6 60 20 E4 FF B0 D0 60 20 8A AD 20 F7 B7 A9 E1 48 A9 46 48 AD F 3 48 AD C 3 AE D 3 AC E 3 28 6C 14 0 8 8D C 3 8E D 3 8C E 3 68 8D F 3 60 20 D4 E1 A6 2D A4 2E A9 2B 20 D8 FF B0 95 60 A9 1 2C A9 0 85 A 20 D4 E1 A5 A A6 2B A4 2C 20 D5 FF B0 57 A5 A F0 17 A2 1C 20 B7 FF 29 10 D0 17 A5 7A C9 2 F0 7 A9 64 A0 A3 4C 1E AB 60 20 B7 FF 29 BF F0 5 A2 1D 4C 37 A4 A5 7B C9 2 D0 E 86 2D 84 2E A9 76 A0 A3 20 1E AB 4C 2A A5 20 8E A6 20 33 A5 4C 77 A6 20 19 E2 20 C0 FF B0 B 60 20 19 E2 A5 49 20 C3 FF 90 C3 4C F9 E0 A9 0 20 BD FF A2 1 A0 0 20 BA FF 20 6 E2 20 57 E2 2 E4 F6 4C DD F6 6C 28 3 6C 2A 3 6C 2C 3 4C 9B F6 4C 5 E5 4C A E5 4C 0 E5 52 52 42 59 43 FE E2 FC 48 FF ...

Searching for stuck data bits.................................................. PASSED
Reading entire ROM contents five times to see if data is consistent/stable...... PASSED


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF

BASIC ROM Tests
---------------
Dumping BASIC ROM:
94 E3 7B E3 43 42 4D 42 41 53 49 43 30 A8 41 A7 1D AD F7 A8 A4 AB BE AB 80 B0 5 AC A4 A9 9F A8 70 A8 27 A9 1C A8 82 A8 D1 A8 3A A9 2E A8 4A A9 2C B8 67 E1 55 E1 64 E1 B2 B3 23 B8 7F AA 9F AA 56 A8 9B A6 5D A6 85 AA 29 E1 BD E1 C6 E1 7A AB 41 A6 39 BC CC BC 58 BC 10 3 7D B3 9E B3 71 BF 97 E0 EA B9 ED BF 64 E2 6B E2 B4 E2 E E3 D B8 7C B7 65 B4 AD B7 8B B7 EC B6 0 B7 2C B7 37 B7 79 69 B8 79 52 B8 7B 2A BA 7B 11 BB 7F 7A BF 50 E8 AF 46 E5 AF 7D B3 BF 5A D3 AE 64 15 B0 45 4E C4 46 4F D2 4E 45 58 D4 44 41 54 C1 49 4E 50 55 54 A3 49 4E 50 55 D4 44 49 CD 52 45 41 C4 4C 45 D4 47 4F 54 CF 52 55 CE 49 C6 52 45 53 54 4F 52 C5 47 4F 53 55 C2 52 45 54 55 52 CE 52 45 CD 53 54 4F D0 4F CE 57 41 49 D4 4C 4F 41 C4 53 41 56 C5 56 45 52 49 46 D9 44 45 C6 50 4F 4B C5 50 52 49 4E 54 A3 50 52 49 4E D4 43 4F 4E D4 4C 49 53 ...

Searching for stuck data bits............................................ PASSED
Reading entire ROM contents ten times to see if data is consistent/stable...... PASSED


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF

CHARACTER ROM Tests
-------------------
Dumping CHARACTER ROM:
3C 66 6E 6E 60 62 3C 0 18 3C 66 7E 66 66 66 0 7C 66 66 7C 66 66 7C 0 3C 66 60 60 60 66 3C 0 78 6C 66 66 66 6C 78 0 7E 60 60 78 60 60 7E 0 7E 60 60 78 60 60 60 0 3C 66 60 6E 66 66 3C 0 66 66 66 7E 66 66 66 0 3C 18 18 18 18 18 3C 0 1E C C C C 6C 38 0 66 6C 78 70 78 6C 66 0 60 60 60 60 60 60 7E 0 63 77 7F 6B 63 63 63 0 66 76 7E 7E 6E 66 66 0 3C 66 66 66 66 66 3C 0 7C 66 66 7C 60 60 60 0 3C 66 66 66 66 3C E 0 7C 66 66 7C 78 6C 66 0 3C 66 60 3C 6 66 3C 0 7E 18 18 18 18 18 18 0 66 66 66 66 66 66 3C 0 66 66 66 66 66 3C 18 0 63 63 63 6B 7F 77 63 0 66 66 3C 18 3C 66 66 0 66 66 66 3C 18 18 18 0 7E 6 C 18 30 60 7E 0 3C 30 30 30 30 30 3C 0 C 12 30 7C 30 62 FC 0 3C C C C C C 3C 0 0 18 3C 7E 18 18 18 18 0 10 30 7F 7F 30 10 0 0 0 0 0 0 0 0 0 18 18 18 18 0 0 18 0 66 66 66 0 0 0 0 0 66 66 FF 66 FF 66 66 0 18 3E 60 3C 6 7C 18 0 62 66 C 18 30 66 46 0 3C 66 3C 38 67 66 3F 0 6 C 18 0 0 0 0 0 C 18 30 30 30 18 C 0 30 18 C C C 18 30 0 0 66 3C FF 3C 66 0 0 0 18 18 7E 18 18 0 0 0 0 0 0 0 18 18 30 0 0 0 7E 0 0 0 0 0 0 0 0 0 18 18 0 0 3 6 C 18 30 60 0 3C 66 6E 76 66 66 3C 0 18 18 38 18 18 18 7E 0 3C 66 6 C 30 60 7E 0 3C 66 6 1C 6 66 3C 0 6 E 1E 66 7F 6 6 0 7E 60 7C 6 6 66 3C 0 3C 66 60 7C 66 66 3C 0 7E 66 C 18 18 18 18 0 3C 66 66 3C 66 66 3C 0 3C 66 66 3E 6 66 3C 0 0 0 18 0 0 18 0 0 0 0 18 ... 

Searching for stuck data bits............................................ PASSED
Reading entire ROM contents ten times to see if data is consistent/stable...... PASSED


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF



DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 



Searching for stuck data bits............................................ PASSED

DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 


Reading all 64KB of DRAM contents twenty times to see if data is consistent/stable...... PASSED


DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 


Testing each DRAM Data bit 10,000 times ...... 
Data Bit 0 PASSED
Data Bit 1 PASSED
Data Bit 2 PASSED
Data Bit 3 PASSED
Data Bit 4 PASSED
Data Bit 5 PASSED
Data Bit 6 PASSED
Data Bit 7 PASSED


DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 


Writing DRAM, waiting one second, then reading back to see if refresh working ...... 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
Writing Reading 
PASSED


DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 


Testing each DRAM Address bit 10,000 times ...... 
Address Bit 0 PASSED
Address Bit 1 PASSED
Address Bit 2 PASSED
Address Bit 3 PASSED
Address Bit 4 PASSED
Address Bit 5 PASSED
Address Bit 6 PASSED
Address Bit 7 PASSED
Address Bit 8 PASSED
Address Bit 9 PASSED
Address Bit 10 PASSED
Address Bit 11 PASSED
Address Bit 12 PASSED
Address Bit 13 PASSED
Address Bit 14 PASSED
Address Bit 15 PASSED


DRAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) DATA: Refresh
4) ADDRESS: Walking Address bit
5) PROBE: All Data Bits Set To 0
6) PROBE: All Data Bits Set To 1
7) PROBE: DRAM Control Logic
x) Exit to Main Menu 



MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF



Color RAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: Color RAM Control Logic
x) Exit to Main Menu 



Searching for stuck data bits............................................ PASSED

Color RAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: Color RAM Control Logic
x) Exit to Main Menu 


Reading Color RAM contents two hundred times to see if data is consistent/stable...... PASSED


Color RAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: Color RAM Control Logic
x) Exit to Main Menu 


Testing each Color RAM Data bit 10,000 times ...... 
Data Bit 0 PASSED
Data Bit 1 PASSED
Data Bit 2 PASSED
Data Bit 3 PASSED


Color RAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: Color RAM Control Logic
x) Exit to Main Menu 


###########################################################
Color RAM Probing Tests - All data bits are set to 0 
Use oscilloscope to see if each data bit is always 0
Data bits for Color RAM are on U6 pins 11,12,13,14
###########################################################


Color RAM Tests
Menu
----
0) DATA: Stuck Data bit
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: Color RAM Control Logic
x) Exit to Main Menu 



MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF



VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 

VIC-II Registers...PASSED


VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 


Reading VIC-II register contents two hundred times to see if data is consistent/stable...... PASSED


VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 


Testing each VIC-II Data bit 10,000 times ...... 
Data Bit 0 PASSED
Data Bit 1 PASSED
Data Bit 2 PASSED
Data Bit 3 PASSED
Data Bit 4 PASSED
Data Bit 5 PASSED
Data Bit 6 PASSED
Data Bit 7 PASSED


VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 


###########################################################
VIC-II Probing Tests - All data bits are set to 0 
Use oscilloscope to see if each data bit is always 0
Data bits for VIC-II are on U19 pins 7,6,5,4,3,2,1,39
###########################################################


VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 

VIC-II Background Color toggle.   *** Last color should be blue ***

VIC-II Tests
Menu
----
0) Register Test
1) DATA: Stability
2) DATA: Walking Data bit
3) PROBE: All Data Bits Set To 0
4) PROBE: All Data Bits Set To 1
5) PROBE: VIC-II Control Logic
6) Change backgroud screen colors
x) Exit to Main Menu 



MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF

########################
########################
SID now generating sound
########################
########################


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF

########################
########################
SID output turned off
########################
########################


MicroCore Labs
MCL64  -- Commodore 64 Board Tester
-----------------------------------

Menu
----
0) Initial tests user can perform with a handheld voltmeter or oscilloscope
1) Run basic test of all chips
2) Test PLA
3) Test KERNAL ROM 
4) Test BASIC ROM 
5) Test CHARACTER ROM 
6) Test DRAM
7) Test Color RAM
8) Test VIC-II
9) Toggle SIC Sound ON/OFF
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Commodore 64 Tester using MCL64