I seem to recall having this conversation in a previous thread a few years ago (was Stuart Bell involved?). Perhaps the best solution is to make more than a single board design (ROM SIMM, XCeed Grey Scale adapter, PDS adapters, etc) and run them through as a flat. When I did board design (in a past life), we typically got 5 flats as a minimum run (1 flat costs the same as 5) with each flat being approximately 64 square inches of material... Tooling is where your money goes. The negative is that all your boards need to be the same thickness, so your grey scale adapter would also end up as a .047 (3/64"). Not really an issue except the board is less stiff. Keep in mind that if you need to go multi-layer, the costs go up as well. I have used the proto services a few times, the boards worked, but I was none too impressed by the quality of the actual board... Things didn't line-up properly... Tracks were connected, but there were often slight offsets where track segments met. But for the price...
Is it really worth doing except for the intellectual challenge? Who knows? Unless enough people agreed to buy, or enough use was found for the flat (to amortize the cost over multiple projects), it would make this hobby quite expensive... Although judging by the prices on eBay now... It already is. Derek On Mar 2, 2009, at 10:09 AM, trag wrote: > > > > On Mar 1, 6:58 am, Raymond Ingles <[email protected]> wrote: >> On Sat, Feb 28, 2009 at 11:12 PM, Derek Morton >> <[email protected]> wrote: > >>> Couldn't we just strip the ROMs from a IIsi and move them to >>> a ROM simm (make our own)? >> >> Should be doable, given the parts. > > The place where this project bogs down is at the circuit board for the > ROM SIMM. There are three basic choices: > > 1) Make your own: If you aren't already set up to do this, it will > cost you more than the other alternatives. You can trade time for > money to an extent, so you might be able to do it with less actual > cash expenditure, if your time has no value. > 2) Buy a few using a commercial proto-type service: Printed circuit > board services typically have two services relevant to us hobbyists. > One of those is proto-typing. Send them your design and for $30 - > $50 per board they'll send you a few copies. There is usually a > minimum purchase that makes this outlay $100 - $200 for 2 - 4 boards. > However, most proto services are not available for this project > because the board specifications in proto service are very limited and > one of the limitation is .062" thick board only. The Mac II family > ROM SIMM is .050" or .047" thick. > 3) Order 200 using a commercial board fabrication service: The other > board service relevant to us hobbyists is just plain old printed > circuit board fabrication. If you order about 200 printed circuit > boards to serve as ROM SIMMs in the Mac II family, the cost will be in > the neighborhood of $600, or $3 per board. $3 per board is very > affordable. However, do you think you could ever sell 200 of them? > 100? How about 50? > > Keep in mind these are just the circuit boards. You must still obtain > ROM chips and solder them to the boards. > > This is the main difficulty in making ROM SIMMs. I have a circuit > board design ready to go--although on reflection there are some > changes I would make now--but the above economic realities mean that > I'll probably never have it fabricated. > > Jeff Walther > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
