David, Fabio, Elsid, Edward, Vince, nbreeden (if I left anybody out please let me know), on this 80386 S100 board and the two associated RAM boards (8MB & 32/64MB capacities) I have decided to just do a run for myself first, (4 of each). Went with PCBCard (over $500). While the changes to the last prototype were very minor as were the changes to the RAM boards, I did “play around” with them with KiCad & Freerouter here, (Normally Andrew handled this stuff), I just could not sleep at night ordering such a large batch of stuff worrying that that bugs crept in. This way only I take the hit. They should be here within two weeks or so. Stay tuned
John
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of David Fry
Sent: Thursday, May 29, 2014 12:16 AM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:3814] Re: An 80386 master/Slave CPU baord with 8 or 32 MB Static RAM boards
I would like 1 x 80386 CPU board and one each of the memory boards 8Mb & 32Mb (with a set of 4 mezzanines) as i am undecided at this point which memory board to do. The AS6C4008 DIP chip is the cheaper chip at about £3.00 UK a piece at Farnell.
On Thursday, May 29, 2014 5:58:57 AM UTC+1, monahanz wrote:
Well it looks like it's finally done. After some 6 prototype boards and one year later it looks like we now have a completely functional S100 bus 80386 board. This board runs on a 21 slot motherboard at 9MHz for all interrupts, I/O ports and RAM from 0 to 16MB. For the remaining RAM (up to 4GB for the 80386) the CPU runs at 36MHz (in pipeline protected mode) and 32 bits wide via two above board cable connectors.
A complete description of the board can be found here:-
There is also a short video of the board in operation towards the bottom of the page.
A major component of this effort was writing the 80386 monitor. It's in fact surprising how little example code there is out the demonstrating the setting up the 80386 to switch from real to protected mode. This is written up here:-
The board currently works with two static RAM boards that sit in the bus but communicate directly (and only) with the 80386. The capacity of these boards are 8 and 32 MB's. These are described here:-
I will be ordering a few "commercial quality" boards for myself. If anybody else would like one of these boards they can let me know. However be aware that these boards are not only complex but expensive to build. The boards themselves are the smallest part of the whole equation. The 8MB static RAM board is a rock solid board and great for testing out the hardware and software but those Alliance Memory Inc. 512x8 static RAM chips cost about $20 each. The 32MB board on the other hand has 4 times the capacity for about the same price but uses SMD chips.
Next up is an 80486 board and the real challenge a 4GB DRAM board!
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