Internals of the Davide Bucci's M20
The machine is a BC model, with two floppies, 128kB of RAM and a B/W monitor.
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.
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.
The 128kB of RAM mounted directly on the motherboard. Additional memory
could be installed with memory expansion cards which could be installed
in slots.
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.
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.
There was a time, not so long ago, when it was possible to read this on a motherboard.
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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