SBC-386EX prototype (rev 0) Board

This board is obsolete. It was strictly used to become familiar with the 386EX processor chip.

This board take several short-cuts: SRAM instead of DRAM, limited peripherals. However, it is a test bed to learn …

1. Enabling the slot-15 I/O ports (all of the on-chip goodies); and disabling them, too.
2. Programming the I/O and memory chip selects. (critical)
3. Using 16-bit and 8-bit mixed ports.
4. Accessing & programming the serial I/O port 0 at 0x03F8.
5. Getting to the timers. Possible automatic determination of CPU clock speed.
6. Using a new access method to get to the DS1302. Three pins on one of the parallel ports should work.
7. Enabling & using the 387SX math co-processor.
8. Accessing peripherals on the ECB bus; i.e., other RetroBrew boards.

DRAM, synchronous serial I/O (SSIO), and DMA will have to wait for another prototype round.

Here's the board 98% built-up, lacking only FPU & RTC crystal: