Starting the New Year with a New-to-me Retro Computer

 Happy New Year, everyone!  I hope you've all had some time off and some rest.  I was able to get alot of small projects done during the break, and I've tried to "clear the decks" a bit to start 2023 on a good footing.

One of the opportunities that came my way in December was finding a couple of people who were purging TI 99 4/A Computers.  I also have not had alot of interest in these machines until I started watching a YouTube Channel called Usagi Electric.  The TI-99 scratches a couple of itches for me.  One of them is my interest in engineering / business failures, or the "Might have beens" of technology development, and the others is my interest in Mini Computers.  I didn't realize it until Usagi mentioned the history that the TI Microprocessor used in this machine was based on their minicomputer architecture.  The rise and fall of TI and their battles with Commodore are one of the more interesting chapters in the early history of the home computer.

Anyway, I was able to get a couple of bundles of unwanted TI-99/4As, four machines in total.  One was working and three were not.  Having a working machine is always a big help and I started watching videos and swapping parts.  Noel's Retro Lab and Adrian's Digital Basement both have helpful series on this machine, although I must confess that I haven't done any board-level troubleshooting yet. I was able to get three of the four systems working and the fourth one has so many things wrong with it that I'm not sure it will be worth repair, I may just keep this as a parts machine for the others.

One of the running machines has an Alps keyboard, so even though it's not the most pristine of the cases I am a bit of keyboard snob and so likely this one will become my favorite TI-99 4A...

I've paired it with a small RCA color TV, model XL100 from 1987.  The image isn't great, perhaps because the tube in this TV is getting tired or because the image is going through an RF modulator.  One of my next steps for this machine is to built a Composite video cable for it so I can use it with a more modern display, I have the parts on order for that from Digikey.  Thanks to Adrian I now know that it's the same cable as the one for a C64 or Vic-20, so I will build a couple of these.

Leave a comment or send me an email if you have any interesting memories of the TI-99/4A!

Really Old Computers - Simulation Using Kits as a Path Forward

As readers of my bLog will know one of my goals in the Retro Computing hobby has been to "move back in time", learning about earlier and earlier computer systems.  Over the last couple of years as I've built my collection and interest in the hobby has increased prices have risen.  The machines that I can afford to buy (as a hobby) are of a certain age and no older.  The machines from the 70's are becoming out of reach for the average hobbyist, including the 1977 "trinity" of pre-assembled home computers; Commodore PET, Apple II, and Radio Shack TRS-80 Model 1.  For machines that are older than that, the original kit built home computers like the Altair 8800, IMSAI 8080 and more obscure machines like the ones that Brad @ Tech Time Traveller covers on YouTube, prices are also quite high.  

Prior to the Home Computer revolution, computers were purchased by companies in smaller numbers and tended to be quite large, so hardware from IBM and the Seven Dwarves isn't a practical target for an individual to buy and tinker with.  Even early "Mini Computers", systems from Data General or Digital Equipment are beyond the limit for most hobbyists in terms of cost, size, and power requirements.

But, there is an option that I've recently become aware of that I've become convinced is a good way to go for those of us who are just learning and aren't yet certain if we are willing (or able) to make the commitments required.  Emulation has proliferated as one of the many benefits of the Open Source software movement, and Hardware Simulation has become easier since only the User Interface needs to be Simulated with the rest of the functionality easily emulated in Software.  There are some really lovely simulators out there now with front panels like; Adwater & Stir's AltairDuino,  High Nibble's IMSAI replica, and Oscar Vermuelen's PiDP-8 replica.

As Oscar explains on his web page one of the many advantages of pursuing the hobby in this way is that these systems are more stable and reliable than the retro computers themselves.  Learning these systems is complicated when running on actual hardware because the hardware is often breaking down due to component age.  Along withe lower cost and no risk of damaging an actual antique, I find that a quite a compelling list of arguments, so I took the plunge and got in an order for the PiDP8 project.  Based on the instructions on the website I was able to get the Pi setup and running before the hardware arrived, and I had that running as shown in my last bLog article about building what looks like a Retro terminal.

While I was waiting for the kit to arrive a friend of mine reached out about a Terminal that he had acquired as a part of a large lot of vintage gear that he had purchased.  He offered to sell it to me at a great price, an offer I couldn't refuse, so now I am the proud owner of a Digital Equipment Corporation VT-520 from 1996.  This was the last Terminal that DEC made and I believe based on the date code that this may have been one of the last of the DEC branded terminals.  I'm quite happy to have gotten it, and because it is compatible with PC keyboards that also lowers the cost of entry.  I've paired it with a very nice clicky Unicomp from 2001...

Shortly after I got the Terminal online with the Raspberry Pi computer, the PiDP8 kit hardware arrived.  The build was time consuming but very well documented. My son helped me start the build, so that was fun.  It's a great looking build as expected...

I couldn't be more pleased with the build, and I'm going to move other computers around to keep this machine easily accessible so that my learning about the operation of the machine and the software can continue.