Re: [N8VEM: 14055] Re: 68030 SBC project ideas

The 386EX is fully integrated. The closest thing in the 486 realm is the GX. It doesn't have the same integrated features (UARTs, DMA, PIC, chip select generation). It's mainly intended for low board area / low power applications. There's actually 24 of them in-stock on Digikey atm.

It's a ton of SMT, but a combination of the 176 pin QFP 486EX, a 240 pin FPGA, and a 44/54 pin SDRAM chip on a small CPU board might be practical for those with reflow ovens and/or drag soldering experience. Would likely also need one or more 24-bit FET buffers to bring the 16-bit data bus plus some chip selects and IRQs out to a 5V tolerant header, a SPI flash for boot rom, and a FT2232H for programming the FPGA and flash in-circuit over USB. That's 6 major SMT ICs, a few small ones, and a ton of passives.

On June 27, 2012 at 1:43 PM Andrew Lynch <ly...@yahoo.com> wrote:

Hi John! Yes, the MC68360 as QFP is <$30 each but as PGA is >$150. Heck, even the PGA sockets are expensive and hard to find! Argh!

SMT soldering is "doable" but large QFPs are no fun. They can be done with some flux, a normal soldering iron and a *LOT* of wick to sop up the excess.

Is there such thing as the highly integrated 486 like the 80C188? Or at least a "companion" chip like a Intel version of the MC68360?

Thanks and have a nice day!

Andrew Lynch

--- On Wed, 6/27/12, John Coffman <jo...@gmail.com> wrote:
From: John Coffman <jo...@gmail.com>
Subject: Re: [N8VEM: 14054] Re: 68030 SBC project ideas
To: n8...@googlegroups.com
Date: Wednesday, June 27, 2012, 1:30 PM
On 06/27/2012 03:37 AM, lynchaj wrote:
I would still like to avoid an overdependence on SMT components
because it limits the numbers of hobbyists who can participate.
The SMT 68360 Quad Flat Pack (QFP) uses 240 x 0.25MM pins on 0.5MM centers.
I don't know what the hobbyist failure rate would be trying to do flow soldering.

PGA uses 100 mil pin spacing, well within the capabilities of hobbyists. A 4-layer board is probably a necessity.

--John
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