Matthew | McJonesTech

a screenshot of KiCad's 3D viewer showing the current state of GloriousCow's Seequa Chameleon motherboard reverse-engineering project. a large green PCB is shown with lots of different components.

What do you do when you want to emulate a computer system that has no schematics and very little documentation?

You just reverse-engineer the entire motherboard with KiCad, of course.

This is the Seequa Chameleon, a dual-CPU IBM PC clone luggable machine from 1983.

#retrocomputing #emulation

Seequa Computer Corporation RAMPlus Board Manual : Seequa Computer Corporation : Free Download, Borrow, and Streaming : Internet Archive This is the installation and user manual for the RAMPlus board for the Seequa Chameleon or Chameleon Plus, from 1985.Learn more about Seequa at seequa.org!

@gloriouscow.bsky.social owns that expansion board. I own a different revision of the same board, called a RAMPlus board. Here’s a manual I scanned in of it on the IA:

archive.org/details/seeq...

Well this is a nice surprise. A desktop Seequa board popped up on eBay this evening! It’s rough, and appears to have had chips blundered and of course no labeling to what was there originally. However, this is now definitive proof the XT and PC sold! #seequa #vintagecomputing

Wait wait wait. Revision J or M motherboards? I’ve only ever found revision J in any Chameleon I’ve seen. I wonder what revision M changed?

A snippet from a Computer Shopper magazine outlining various Seequa items for sale.

Check out this cap of a Computer Shopper from 1987: Chameleon Schematics, Short Stuff expansion cards, and bare motherboards! Would love to know if anyone picked these up.

#retrocomputing #seequa

Alley Cat running on the internal CRT of my Seequa Chameleon.

Alley Cat in a custom addressed CGA palette on my Seequa Chameleon.

Posting here alongside my Mastodon (mcjonestech@oldbytes.space), the Seequa Chameleon also allows for customized CGA color palettes via an OPTION program! Here is Alley Cat running in red white and blue, straight from composite!

#seequa #retrocomputing

I’d assume they’re being optimistic. The PAL chips on these machines (18 in total) are a worry of mine because of data retention, but yeah I’d assume 100 years isn’t right

I believe so! With data retention of a hundred years! At least… in theory I guess I don’t know how they supposedly measured that lol

Sorta! It’s half volatile and half non-volatile, where data written to the volatile memory is copied to the non-volatile memory.

The XD2210 64x4 nonvolitile memory chip that holds BIOS configurations on the Seequa Chameleon.

Did you know the 1982 Seequa Chameleon could save BIOS configurations via a DOS program? If you’re thinking it did so via a button battery, you’d be wrong! The Chameleon used this dinky XD2210 64x4 NOVRAM memory chip to store it!

Thanks to @gloriouscow.bsky.social for finding this!

Seequa Computer Corporation RAMPlus Board Manual : Seequa Computer Corporation : Free Download, Borrow, and Streaming : Internet Archive This is the installation and user manual for the RAMPlus board for the Seequa Chameleon or Chameleon Plus, from 1985.Learn more about Seequa at seequa.org!

I also (finally) cleaned up my scans of the Seequa RAMPlus board manual! At some point I’ll need to scan in my RAMPlus board for analysis and possible recreation, but for now here is the manual.

archive.org/details/seeq...

Inside Seequa Volume 1 Number 1 : Seequa Computer Corporation : Free Download, Borrow, and Streaming : Internet Archive January/February 1984 issue of the Seequa Computer Corporation's Inside Seequa magazine.Read more about Seequa at seequa.org!

I've uploaded all three Inside Seequa editions to the Internet Archive!

Inside Seequa was an internal newsletter for employees of Seequa, and gives insights into the people behind the computers and events in 1984.

archive.org/details/insi...
archive.org/details/insi...
archive.org/details/insi...

Every single Chameleon has those two wires, plus every bodge on the back is unique per Chameleon. I have some older photos of production where those wires are very visible.

A photo of a filthy motherboard from a clone IBM XT machine called the Seequa Chameleon. Two of the ROM chips have been removed, revealing a startling contrast as the PCB beneath them is spotless, bright green, while the rest of the board looks like it is caked in mud.

Successfully dumped the ROMs from this absolutely disgusting Seequa Chameleon motherboard. You can see how clean it was *supposed* to be, underneath.

Turns out it was a version with no prior good dump, so that's cool!

@mcjonestech.com

#retrocomputing

My Gemini Zorba from VCFMW! (It burned up sometime a little after this photo)

Does anyone happen to know what is up with the Zorba timeline? I am working what I thought were the only three Zorba models (Telcon, Modcomp, Gemini), but I found something called a "Nomis 9", and other models? I feel like this is more complicated than it needs to be, haha!

#zorba #vintagecomputing

Thank you! They’re still works in progress (I think my early Chameleon is having some logic issues but have yet to figure out exactly what) but it was nice to get the name out in the public once again, now I just need to find the desktop models! 😁

A stack of Inside Seequa magazines, alongside Dealer sheets, pricing information, and other paper media regarding the Seequa Computer Corporation.

I was able to get in contact with the EVP of Seequa, and a care package showed up at my door. Probably a days worth of scanning in here.

Friday at 8PM EST we will be going through all of these and updating history in real time over at twitch.tv/mcjonestech , I hope you can join!

Absolutely! More than happy to fire one up and see what we can figure out. I’d love to!

That’s wild. I am truly impressed you were able to get all this functional and figure everything out so quickly!

So I presume you had to set the enable bit on in CGA for that to display?

I’ll also try it on the real hardware! I had Flight Simulator running on one of them at the show until it stopped reading disks entirely (still stumped on that one), but that also is a booter game and it seemed to like that just fine.

That is awesome! There are no DIP switches on the board, correct, interesting that you’re getting beep codes: I have found when one of these has a problem (ie failing 4164 or an NMI) it force boots and eventually fails out, or doesn’t boot at all. Normally, they just beep a couple times at boot.

Files - Seequa Chameleon Resources and Files for the Seequa Chameleon.

This is all super impressive!!

The ROM is available at seequa.org/gallery/ch-files for your reference. I have several versions of it, and some of them used more than one ROM chip.

It was fun chatting with you! You’ll have to keep me updated on any findings you make from my disk and rom dumps!

A Seequa Chameleon motherboard, annotated. Seen are the z80 and 8088 chips, and the on-board CGA with the MC6845 CRTC chip.

One of the cool things I saw at #VCFMW was the Seequa Chameleon at an exhbit by @mcjonestech.com

This was a series of PCs that could switch between a Z80 and an 8088 CPU.

Conspicuously lacking ISA ports - there's a CGA integrated onto the board (note the MC6845).

I stepped away from my booth for ~5 minutes or so Saturday, and when I came back Natalie said someone asked if she was the Macintosh Librarian (surrounded by CP/M and DOS machines, lol). I am so glad I found the live stream where this happened, she said to me "I wish I was that cool" #vcfmw

Ohhhh I am very much aware. I took on getting a Chameleon and its younger brother the Chameleon Plus restored a few months ago. At least they labelled every chip. In my very large amount of research I’ve conducted on these, the people that assembled them had never seen a computer before.

Have you happened to fix this unit yet?