Whats in the box?

• VIC-20 Dead Test Rom: Complete with ROM adapter for installation into a legacy VIC-20 ROM socket.

Professional-Grade Fully programmed Commodore VIC-20 Dead test ROM

NEW from Any Retro!

Everything you need to quickly and completely test your beloved Commodore VIC-20.

This Dead Test Rom, plugs into the internal Kernel ROM socket of your VIC-20 computer. If your Kernel ROM is soldered to the main board, then you must first de-solder the ROM and replace it with an IC socket. Some boards already have the Kernel ROM.

The Kernel ROM is identified by the following numbers depending on the machine:

• 901486-06 - NTSC VIC-20
• 901486-07 - PAL VIC-20
• 901486-02 - Japanese VIC-20

This Dead Test makes a great addition to our new Diagnostic Test Cartridge (not included) that completely tests the inner workings of the computer, this set also includes all the necessary dongles to test the external ports:

• Keyboard
• Serial
• Cassette
• User port
• Joystick port

See our other listing for the diagnostic cartridge and harness.

Multiple diagnostic tests per component include:

• Zero Page
• Stack
• Internal Ram
• External Ram (if present)
• Screen Ram
• Character Rom
• Basic Rom
• Kernel Rom(s), including PAL/NTSC detection
• JiffyDOS compatible
• VIC chip specific tests
• Color Ram
• Casette Port
• User Port
• Serial IEC floppy port
• VIA1
• VIA2
• IRQ/NMI tests
• Sound tests

Advanced memory testing algorithms

Go deep to find RAM memory faults:

• March C- — w0; r0,w1 up; r1,w0 up; r0,w1 down; r1,w0 down; r0. Catches stuck bits, transition faults, and address-decoder faults.
• Solid patterns — $00, $FF, $55, $AA, each written then read back.
• Address uniqueness — low byte of the address stored in each cell, then the high byte. Catches aliased or shorted address lines.
• Walking ones — $01, $02, … $80 written and read at every address. Catches stuck bits and bit coupling.

The dead test ROM is especially important as it can indicate faults that the diagnostic cartridge cannot, such as RAM faults that stop the machine booting. The dead test ROM achieves this by running dedicated RAM tests as soon as the CPU is initialized. It can indicate RAM faults by flashing the screen RED to indicate a fault before the rest of the system is even initialized.

The number of flashes indicates the fault and the affected IC:

Compatibility

• Works with PAL and NTSC VIC-20s and detects which one you have.
• Works on a stock, unexpanded machine. Tests 3K and 8K expansion RAM if you have it fitted.
• No disk drive, tape deck or software needed. Everything runs from the ROM.

How to use it

• Switch the VIC-20 off.
• Remove the original Kernel IC from it's socket. Note - If the original VIC-20 Kernel does not have a socket, then you will need to desolder the ROM chip from the main board and solder an empty socket in it's place. Approach an expert to do this for you if you are not comfortable doing this. AnyRetro cannot be held responsible for any damages resulting in modifications made by customers to their motherboards.
• Plug the dead test ROM board into the kernel socket, paying attention to the chips lip alignment with the board lip and not bending pins.
• Switch on. The tests start straight away.
• Watch the screen for any RED flashes, before the test progress to testing the system mainboard components.
• After each full pass it pauses for a couple of seconds and starts again. Leave it running as long as you like to soak-test the machine.