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Edwin Blink

Edwin Blink

The Disk Protector Unit or DPU for short is a small circuit designed to cure the SAM’s disk corruption problem whenever the SAM is reset or turned on with a disk in the floppy drive.

The problem is caused by the ASICs 8 MHz clock which is halted during reset and then causes the floppydiskcontroller go out of control. Because the floppydiskcontroller needs a constant 8 MHz clock all the time.

All that the DPU does is generate a constant 8MHz clock to replace the ASIC’s 8 MHz clock. The design is simple and easy to build. Only half of the 74LS04 IC is required for the DPU. The other half of the 74LS04 IC can be used to make a NMI debounce switch.

See the DPU Page