M20 Olivetti M20

Internals of the Davide Bucci's M20

The machine is a BC model, with two floppies, 128kB of RAM and a B/W monitor.

Motherboard A view of the motherboard with the disk drives and the keyboard removed. On the left, we can see the Zilog Z8001 processor. On the center, the 128kB of RAM organized as 16x64kbit NEC 6164 DRAM chips. On the right, the expansion connectors.

Zilog Z8001 One of the most interesting features of the M20 is the use of the Zilog Z8001 processor, which was a 16-bit development based on the successful Z80 design.

128kB memory The 128kB of RAM mounted directly on the motherboard. Additional memory could be installed with memory expansion cards which could be installed in slots.

Keyboard The keyboard and the disk drive protection. The keyboard is controlled by a stand-alone microcontroller which communicates with the motherboard with a serial communication. On the keyboard there is a small buzzer wich was useful to indicate various operating conditions. The keyboard layout shown is the longago forgotten standard typewriter Italian layout.

Disk drives The disk drive assembly. These drives are full-height 5"1/4 units, which means that by today's standards they are BIG and relatively heavy.

Made in Italy There was a time, not so long ago, when it was possible to read this on a motherboard.

Power Supply The power supply taken apart. Note the two filter capacitors on the left side of the board. They can be charged up to 400V and can stock a dangerous voltage for quite a while after the mains is disconnected. Be careful!




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