DesTest MAX-Switch

The MAX-mode of the C64 expansion-port is truly a marvel since it allows the program on the cartridge to run right from the get-go bypassing the kernal and its assumptions about working memory.  This convenience, however, comes at a cost:  All but the bottom 4K of memory plus the kernal, BASIC and character ROMs are not available.

That's why DesTestMAX only tests 4K!  That's all it can test.

The DesTest MAX-Switch (or just the 'Switch) solution aims to fix this limitation!

The custom DesTest MAX-Switch cartridge adds the capability to switch (hence the name) between the MAX-mode and regular cartridge-mode under program control.  The new DesTest Software allows the following features:

• Full 64K memory test using the March-B algorithm.
• No dependence on the ROMs, CIAs or SID: they can be removed.
• ROM checksum verification (if installed).
• CIA TOD consistency verification.

The DesTest MAX-Switch hardware includes provisions for the following:

• Power LED.  Most of the time when diagnosing or repairing a C64, the keyboard is removed along with the Power LED.  The DesTest MAX-Switch cartridge includes a simple power LED to avoid mistakes like removing or inserting ICs with the power on.
• Reset Switch and LED.  A faulty reset-circuit in a C64 can prevent it starting-up properly.  A reset-switch can temporarily bypass a faulty reset-circuit and the LED gives a visual indication if something is wrong!