A Peek Inside the Merlin II Prototype

As you can see, the Merlin II was built from a "sandwich" of two different boards. The lower part was done in the reverse wire wrap style invented by Ruy Pinto Cesar Neto. The upper board was the first one design using CAD at Softec.

The upper board included 1MB of DRAM as well as the address multiplexors and video shifters. The video could be any resolution up to 64K with 16 colors. Though the 68000 CPU has only 16 bits of data, the video section worked in 32 bits for better performance.

The lower board contained the CPU, all system timing and Brazil's first Ethernet interface ( using an AMD 7990 LANCE chip ). The use of a PAL in the timing section was also a first at Softec. The video controller was a simple state machine implemented using an EPROM. Up to four different monitors could be supported.

The Ethernet interface proved to be a major problem as import restrictions made it necessary to develop our own PC LAN card just to be able to develop the prototype. This extra effort was not successful and delayed the whole project.


see also:
| merlin2i | | merlin2s |
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| merlin2 | | history | | merlin | | LSI | | USP |

please send comments to jecel@lsi.usp.br (Jecel Mattos de Assumpcao Jr), who changed this page on Jun 29, 17:08 .