Friday, August 13, 2021

Mini PET 40/80 Build & Review



The New Tynemouth & Mini PET

Back in 2020 Tynemouth Software released the Mini PET onto a largely unsuspecting retro computer kit appreciating public. 2021 sees the release of a significant update to the standalone kit in the form of the Mini PET 40/80. What's it like? How easy is it to build? How usable is it? Lets find out.

A new PET in a Kit

At first the Commodore Personal Electronic Transactor (PET) seems an unlikely choice for a computer kit, being possibly the least widely used of the classic Commodore computer lines. Then again PETs are the raison d'être for all subsequent Commodores and for that reason alone places the PET line in a very special place.

Now there were quite a variety PETs produced, the the first being the 2001 series, going all the way up to SuperPET 9000s. But what type of PET is a Tynemouth Mini PET 40/80? Well, it's most of them and none of them all at the same time (well kind of). Internally the Mini PET 40/80, as the name suggests is a 32k PET 4000 series / CBM 8000 series clone, yet it takes the stylised keyboard from the original 2001.

Unlike Commodore PETs, Tynemouth / TFW8b PETs come unassembled, and in that state it's pretty damn impressive. Mr Tynemouth aka Dave Currans' kits are normally impressive enough, but with the powers of TFW8b & Tynemouth combined something special awaits the keen kit builder this time around. 

The kit comes in quite the box; A light blue Commodore Pin Stripping cover sleeve cloaks the contents, imparting that essential Commodore-ish-ness of what lays within. Once opened our container reveals an equally special spiral bound assembly booklet, a PCB, the required ICs and other components neatly arranged out on build trays, plus a host of laser cut perspex sheeting that will go on to form the computers case.

The Opened PET kit ready to roll.

Thanks to all the hard work that's gone into first impressions, there's no sense of dread to be had before embarking on the build, quite the opposite, you can't wait to get the PET together.

Build a PET

As alluded to earlier, the build manual is a kit highlight, not only striking in it's design references, it is perhaps more importantly for the purposes of kit building a very clear and well laid out reference. Being spiral bound the manual is easy to lay flat during the step by step kit building processes and each stage of the build is presented at the appropriate time. (with the possible exception of step 3, the Crystal and Transistor mounting, which I'd recommend swapping with step 4.)

Building the PET is a breeze, well more of a long gust, there's a lot to solder after all. The PCB is cleanly laid out with part placement quickly referenced in the manual. Conveniently all the IC's / Sockets are laid parallel and facing the same direction, a trait shared with other matched components such as diodes, a nice touch that makes it quite difficult to solder polarised parts incorrectly rotated.

One thing to note while building up the PCB; the solder pads around the IC's are on the smaller side, I found the use of a flux pen greatly improved my soldering experience. 

Key Craft - Cut & Place

Perhaps the weakest point of the original Mini PET was its 'tack switch' based keyboard. Not having an example of the previous model I can't reliably comment fully, still I think we can all intuitively 'feel' the issue. The Mini PET 40/80 has addressed all concerns while managing to keep a satisfying retro feel. Omron B3f Series switches underpin the keyboard this time around, Cherry MX (or 9mm Guy Preferred) they are not, though they are rather pleasant to use and should serve extremely well. In situ surrounded by a bezel the keyboard looks the part, really completing out that retro PET styling. This keyboard gets an A+ from me for effort and details (and even feel).

Once at the keyboard legend decal stage you'll have quite the arts and craft session ahead of you. 87 legend cutouts required for placement under clear keycap tops. Thankfully the kit comes equipt with several copies of the keyboard decal sheets should you make a mistake.

That leaves us with the final case assembly, and what a fine bit of work that is. Held firm on a dark base plate, the white circuit board and bezel plates all topped off with a clear laser cut etched panel, completed and all together the Mini Pet 40/80 is gorgeous.

PET Handling

Of course the most exciting part of any kit is powering it on for the first time. I was instantly greeted with the "*** MINI PET BASIC 4.1 ***" header; for what must be a first for me it all worked straight out of the gate. Good omens!.

One Mini Pet 40/80 All Together on the Workbench

Next, to test some software, I'd grabbed some PET software off the Net and loaded all manner of things up, and no issues at all. The Mini PET seems perfectly compatible with all the software I'd tried in 40 and 80 column modes. 

I'd definitely recommend purchasing the "SD2PET Future" interface alongside the PET kit if you don't already have one, particularly if you don't a Commodore Datasette (or Disk Drive), else you'll need to load manually via person on keyboard entry, all old school like.

PET Video

We have a number of video modes to choose from, some of which are quite exciting if you happen to have the correct monitor. There are the usual composite PAL and NTSC, real PET Monitor Specific modes, of more interest to some are the options for RGBI/CGA and MDA/Hercules.

Composite video quality is crystal clear when viewed on a CRT in either NTSC or PAL, and no less stunning through the my cheep and cheerful HD Video Converter. With the clarity available from composite there's not a lot of need fort RGBI or MDA except that it gives you the choice of switching on a retro green screen mode.

Close up of Composite Video on an LCD screen

I found CGA/RGBI mode is a mixed bag, although I believe that with a genuine CGA capable monitor (including the infamous Commodore 1024s series) RGBI would be quite stunning, however I have don't have an RGBI monitor to test with. What I do have are a number of CGA to VGA converters, and the picture from these was a touch disappointing, with colour ghosting and artefacting as if the phase was out. I couldn't find a way to rectify this easily. Your millage with video converters may vary significantly. On the other Hand MDA/Hercules I was able to convert perfectly. 

Similar image through RGBI with colour bleeding (note this most likely an issue with the conversion process not the actual video output)

Regardless of RGBI issues, as stated above the Composite is so crystal clear that it's no major loss if you can't get a particular RGBI converter to work as expected, or if you don't have a CGA/RGBI monitor to hand.

An Update on CGA / RGBI Video Output

Not being satisfied with the CGA to VGA converter result, I dug out an RGBI to RGBS converter I had in a draw and married that up to a SCART to HDMI converter.  The results are much clearer than I'd achieved with the CGA box. I think we can say definitively that the Mini PET puts out a pretty decent RGBI image (which would look brilliant on a CGA monitor).


RGBI converted to RGBS and run through a SCART to HDMI Converter. A much better Image.

For sharpest results with minimal fuss I'd still recommend simply upping the Composite video to VGA or HDMI, or maybe going straight to a TV depending.

Should You Adopt a PET?

In short YES! 

If you're interested in Commodore computers and kits, then this kit is for you. All in all this was a fun build and I'm certainly looking forward to experiencing the PET for what it is and was. The Mini Pet 40/80 is quite simply a brilliant kit computer, by far one of the most enjoyable kits I've ever built.

Adopt your own PET today from Tynemouth Software &

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  1. When did you order and when was it delivered? I'm still waiting eagerly for my delivery! 😊

    1. I Pre-Ordered in the previous round. It's well worth the wait, I promise.