/* Imported from Wayback Machine
   Original URL : https://www.retrobrewcomputers.org/doku.php?id=boards:sbc:sbc-386ex:rev0
   Snapshot date: 2022-09-29
   Generator    : wayback-archiver
*/

====== SBC-386EX prototype (rev 0) Board ======

This board is obsolete.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

==== The prototype board SBC-386EX-0 ====

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=b330fc&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/boards/sbc/img_0944_sm.jpg|{{https://www.retrobrewcomputers.org/lib/exe/fetch.php?w=716&h=440&tok=ad12a9&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fboards%2Fsbc%2Fimg_0944_sm.jpg?716x440|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_boards_sbc_img_0944_sm.jpg}}]]

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

Enabling the slot-15 I/O ports (all of the on-chip goodies); and disabling them, too.

Programming the I/O and memory chip selects. (critical)

Using 16-bit and 8-bit mixed ports.

Accessing & programming the serial I/O port 0 at 0x03F8.

Getting to the timers. Possible automatic determination of CPU clock speed.

Using a new access method to get to the DS1302. Three pins on one of the parallel ports should work.

Enabling & using the 387SX math co-processor.

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.

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

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=434639&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/boards/sbc/img_0948_sm.jpg|{{https://www.retrobrewcomputers.org/lib/exe/fetch.php?w=800&h=516&tok=69e3dd&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fboards%2Fsbc%2Fimg_0948_sm.jpg?800x516|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_boards_sbc_img_0948_sm.jpg}}]]