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
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