Way too much detail about breadboards

Unobtanium!
Just to prove it exists, here's my Global Specialties Corp "Experimenter 600" breadboard with a WIDE gap in the center for .6" chips.
The Global Specialties web site shows the .3" center version and a similar one with 2 busses per edge instead of one.
See how neatly the 4: HP 5082-7340 hex displays fit!

Somehow I have the history of the breadboard company as it changed names from Elenco Precision to Continental Specialties to Global Specialties (with or without logo), and even labelled "Archer" for Tandy/Radio Shack. The .3" center breadboard's remained mostly unchanged for all these years. The Elenco Precision Breadblox model 9550 had slots in the center and only 2 mounting holes compared to the solid center and 4 mounting holes of the Experimentor 300.

Meet the family of Experimentor breadboards: quad bus, .3 and .6 inch centers.

I like the way the Global Specialties Experimentor breadboards interlock on all sides.

Okay, who's playing with the TARDIS controls? I just accidentally stepped into a time-wormhole while sorting thru a magic box-o-parts and found 2 positively ancient

Elenco Precision
Breadboard Aids
breadblox model no. 9550 (label) 9555 (tag)
550 tie points with two power lines

MINT IN BAG: one of the old ones!
And on the right, an AP Products 432-875 really minimal breadboard (no numbers/lettering, no busses, no mounting holes, no edge strips or tabs to click together).

OLD LABEL & tag
Oh my! None of the numbers match!
On top is the rear label from the pre-model 300 breadboard.
It's exactly same size (a little under 6"), 47 columns of clips, 5 per side, and one bus bar to each side with 8 groups of 5 contacts. But it's labelled the "model no. 9550, 550 tie points with two power lines". Technically, it's correct:
47 x 10 = 470 central contacts (called jacks on the tag),
8 x 5 = 40 contacts per bus, x 2 busses = 80 bus contacts,
470 + 80 = 550.

But the bag label says "part no 9555" which does not match the breadboard's label or even the back of the bag which lists even larger "bredblox" (different spelling). The bag tag lists this as "no. 9415 with 470 jacks and 5 5/16" lgth" but I measured it as 5 15/16"! Had they made the no. 9416 with 590 jacks, that's 59 columns (vs. 47 of the model 300) which would have compared favorable to the 63 columns on the 6.5" ones by EIC (even the same length!)

The top one with the binding posts is the Elenco, the bottom one a matching contemporary Global Specialties Corp Experimenter 300 breadboard.

The Elenco's so old that the rear labels have neatly fallen off, revealing the same contacts still used by the Experimenter (as seen as label indentations).

This opens up some interesting opportunities

connect the binding posts to the power lines
mount the breadboard to a prototype system (PIC, AVR, etc) and wire the bottom of the tie-points directly to signals of interest so everything's just one jumper-wire away
but what to use as insulation under the bare contacts: fish paper? thin plastic? Whatever felt or fabric I have in reach?

Update: Robin Whittle did that years ago with his DIY Audio Patchbay made from a Solderless Breadboard.
Inspired by this web page, he documented his other breadboards.

Other breadboard makers

EIC vs. Global breadboards
Admittedly, the Global Specialties "EXP" (Experimentor) breadboards (bottom) have fewer tie-points than similarly-sized E.I.C. brand breadboards (center, top) but it's one solid piece with channels that connect in all ways. Counting only the 10-across rows:

30 on the tiny EIC
63 on the 6.5" EIC
47 on the Global Experimentor 300, 600

NOTE how the tabs on the small EIC do NOT match the larger EIC: they cannot connect!

And another gotcha: on SOME breadboards, the side busses go all the way, others are spilt in the center WITHOUT ANY MARKINGS TO WARN YOU! I guess it's kinda implied by the subtly greater space between the center holes.

And the other accessories:
Yes, I have the ubiquitious bug box, the Archer/Radio Shack pack of scratchpads for the Global experimenter 300 and a tiny E.I.C. breadboard (the ones with color imprints).
Inside the BugBox are spare contacts from a REALLY OLD AP breadboard where I had to assemble it myself: push in all the contacts!

And no-name generics

On the right: This mail-order breadboard came pre-mounted on a blue metal backplane.
There's no mfgr's name: the box says only "R.S.R. NE #304 solderless breadboard". What a gyp!

only says "durable & 100% contact", no assurance of nickel-silver spring clip contacts
NO markings at all for grid, busses (I suspect the busses are SPLIT in the center: notice the subtle difference in spacing!)
NO clips or interlocks, only mounting holes to use more than one

Here's the tiny EIC on top of the R.S.R.
See how much easier it is to read the EIC markings and bus designations?

My NJIT 68000 trainer lab kit
has a remarkably similar generic breadboard but with numbers. I inked the red marks to remind myself of the split busses.

Some have totally yellowed, some not at all, some barely yellowed at the edges. I'm unsure if it's anything about how & where I stored, them, etc. Apropos of that: retr0bright is a clever solution for case yellowing.

updated 1-Oct-2009