Lisa with ROM Switcher on eBay

[AlexTheCat123]

Someone just listed a Lisa on eBay with a ROM switcher installed that lets you change between H and 3A ROMs (as well as the MacWorks screen mod) with the flip of a switch. I've heard about these switchers, but I've never actually seen pictures of one, so I figured I'd post this here in case anyone else wants to take a look!

[Lisa2]

There is more RomSwitcher info on bitsavers:

http://www.bitsavers.org/pdf/apple/lisa/macintosh_xl/

[AlexTheCat123]

Good to know! I had no idea that there was anything on Bitsavers about these things.

[Lisa2]

For completeness on this subject, the Sapient CPU recreation has among it's many enhancements has a built-in ROM Switcher. Using 256K EPROMS and a special VideoProm that supports four Lisa ROM sets (versions H,D, C, and 3A ).  The ROMs are selected using some switches on the board but these switches can routed externally also.  A photo of this board is attached, (please ignore the XLerator in the photo)

I made a very rough video of the operation here:
https://youtu.be/56KtI2uQaWg

Note: if switching between the older (H, D, C) and screen mod ROMs (3A) the screen pots really need to be adjusted. The original ROM switcher instructions recommend a compromise of settings between the two setups.   Neither the original ROM switcher nor the Sapient board switch in the yoke transformer for the screen mod. 
Rick

[Lisa1]

Anyone know where I can find a working ROM Switcher?

[TorZidan]

I have it, too. It came unexpectedly with my 1st Lisa (2/10) that my neighbor placed on a trash collection pile in front of his house ~ 15 years ago.

It basically switches on/off a Square Pixel Modification Kit.

The board is plugged in place of the two ROMs and also via ribbon cable into the video ROM on the CPU board.
The flip switch (Mac <-> Lisa) engages/bypasses the small transformer that is located near the video board, and also (via 2 separate pins) is connected to the board to turn it on/off.

Here are some photos that I just took. Enjoy.

It's not for sale, but if someone wants to reverse engineer it, I will "cooperate".

[ried]

That is so cool! Want

Edit #2: So this little thing switches out the CPU ROMs, video state ROM, and also bypasses the screen mod transformer with the flip of one switch. Neat!