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Tests

Lower RAM

When the diagnostics ROM starts, it does a test of the lower RAM. You may see some flashing on the screen while that's happening. The memory passes all the tests, it reports it with this screen.

Otherwise you'll get a screen like this:

Each bar corresponds to one data bit. Green bars mean that bit passed all the tests, red bars that it failed. Usually each bit corresponds to a different RAM IC, so that tells you which ones need replacing.

Use the table corresponding to your model to know which IC needs to be replaced:

CPC 464 and CPC 664

Bit	IC
0	IC120
1	IC119
2	IC118
3	IC117
4	IC121
5	IC122
6	IC123
7	IC124

CPC 6128

Bit	IC
0	IC127
1	IC128
2	IC129
3	IC130
4	IC131
5	IC132
6	IC133
7	IC134

464 Plus, 6128 Plus and GX4000

Bit	IC
0-3	IC110
4-7	IC111

Upper RAM

The diagnostics program tries to find all available upper RAM up to 4MB. It displays graphically the different banks and performs a test on them to make sure the memory works correctly.

This is a successful upper RAM test with an expansion of 512KB.

If an error is detected, the failing bits are listed so you can find the ICs that could be causing that.

The following table shows which IC is associated with each bit:

CPC 6128

Bit	IC
0	119
1	120
2	121
3	122
4	123
5	124
6	125
7	126

6128 Plus

Bit	IC
0-3	IC112
4-7	IC113

The program also checks if the "C3" memory configuration is supported with that upper RAM (some expansion don't support it correctly).

ROM Tests

The program will access the system ROMs and make sure they match known ones. This is useful to detect if there's a corrupt ROM preventing the system from working correctly.

Keyboard Test

This is an interactive tool to help you test the keyboard. Press all the keys to make sure all keys are working correctly.

System Info

Right now only CRT controller type is printed.

TODO

• Better RAM tests
• Detect addressing problems vs bit problems
• Identify ROMs in more languages
• Sound tests
• Disk controller tests