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V9958 - Getting Started

A project log for rosco_m68k

A full-featured Motorola 68k retro computer, starring a 68010 running at 8MHz

Ross BamfordRoss Bamford 04/27/2020 at 02:020 Comments

I had a little time this weekend, so I finally made a start with the V9958s I received a couple of weeks ago. I've not gotten all that far, but I have sanity checked that I can power the chips and hook them up to the bus on the rosco_m68k. As is tradition on this project, I want to develop the thing on breadboard before committing to a design (especially given the 9958 is completely new to me) but there's a hiccup - the V9958 comes in a 1.77mm pitch "Shrink DIP" package, which obviously isn't breadboard friendly.

I looked around on the nets for an adapter, and while I did find one (that was oddly enough designed for the V9958 and included the crystal and caps) it didn't ship outside the US. I also found a generic SDIP64 to breadboard converter on Amazon, but that one was out of stock. No matter, I fired up KiCAD and ran off a simple adapter in PCBnew:

I did this about ten days ago, and JLC had it back to me in a few days (I guess because it's such a simple board, in green and quite small, they were able to panel it more quickly than my usual oddball-sized-and-shaped-boards-in-blue) and of course it works great. In the pic above I've attached power and the clock - later I hooked up the bus and was able to get the chip talking to the computer in a rudimentary fashion. Because of the width of the adapter it doesn't fit 'normally' into the breadboard, and has to straddle the power rail of two side-by-side boards, but that's no problem.

I have a bunch of these little adapters, so if anyone is doing anything breadboard-based and needs to work with a wide SDIP of up-to 64-pin, let me know and I'll list them on Tindie for around $5 including shipping.

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