Building a "Terminal" out of Retro Parts

As I work my way back in time in my Retro Computing journey, it's time for me to get a Terminal.  Ideally I'd like to get a VT-320 as this is the interface that I remember using most frequently during my college years to access the DEC Vax systems in the computer labs.  These labs were filled with 30-40 terminals each and were large enough for lab classes to meet with everyone logged into the Vax at the same time, or to use for programming assignment when classes were not in session.

As interest in retro computing has risen, so have the prices of these terminals, with these "newer" 20 year old terminals selling on eBay around $300, sometimes without keyboards that could cost another $50 to $100.

What is a retro computing hobbyist to do?  I encountered a suggestion on a kit building website about directly attaching a display and keyboard to a Raspberry Pi and remembered that I still had a few RPi's in storage from projects that I'm not using any more.  What followed is this:

This "Terminal" consists of an early VGA Monitor (640x480 only, not multi-sync), and a nice Omnikey 101 keyboard which I have previously covered on the bLog.  Here's what I did to get the retro monitor and keyboard working with the Pi...

I started with the current base image of Raspberry Pi OS (32-bit, lite version).  I'm running this on an RPi 2, since that's what I had around, but I did want WiFi connectivity so there's a dongle plugged into a USB port.

I plugged the Pi in with a modern USB Keyboard and HDMI Monitor to start, and used raspi-config to setup the networking, enable ssh, change the password, and get the display configured.  Using the information from this article, I set the display resolution to DMT 640x480@60Hz.  After restarting the Pi, I double checked the image resolution and it was indeed lowered to the required resolution.

After checking that, I was able to connect the Keyboard with a PS/2 to USB adapter that I had laying around.  I don't have a model number but if you use a Northgate Keyboard I'd recommend reaching out to Bob @ Northgate Keyboard Repair as I've heard that these keyboards can be somewhat picky about which adapters work well.  Once the keyboard was tested and working with the Pi I moved on to the Retro Monitor.

In order to plug the VGA monitor into the Pi, we need an HDMI to VGA adapter, these are commonly used to connect laptops with old projectors so they are still available.  I used an Inland brand I had around, but I've also ordered a couple of replacements on Amazon here that I will test when they arrive.  Plugging this in, it worked right away.  It's so fun to see the colorful Raspberry Pi Boot menu on this late 80s / early 90s combination of hardware!

Here's a list of the hardware in the build:

    5 Volt Power Adapter (not shown)

    Raspberry Pi 2 w/ Case

    WiFi Dongle for RPi

    Inland HDMI to VGA Adapter Dongle

    PS/2 to USB Keyboard Adapter Dongle

    VGA Monitor w/ Cords

    PS/2 Keyboard w/ Cord

And a picture of what the connections look like at the back.

Longer term, I might add a Serial Port for attaching to other Retro Computers, but my immediate use case is for a kit that I've ordered with emulation running directly on the RPi, so this Pi will be removed from its case and transplanted into that kit when it arrives.  I'm sure I'll be blogging about that when the time comes, so stay tuned!

Do you have an old terminal system, or good memories of using these systems back in the day?  Let me know in a comment, or feel free to drop me an email.

NeXT Megapixel Display N4000A Repairs

 As you may have seen previously on my blog, I'm fortunate to be the custodian of a NeXTStation setup that I purchased at last year's Vintage Computer Festival - Midwest.

Since blogging about that machine, I've recapped the mainboard, added an External SCSI CD-ROM so I can load software the old fashioned way, and upgraded the Hard Drive to a 2GB Quantum Fireball (Fingers crossed, it's still working!).  One outstanding issue with the machine has been that the audio on the monitor has not worked since I owned the machine.

According to this article, on the nextcomputers.org forum, it was likely that a circuit board in the monitor need to be recapped.  I finally got the time to tear into the monitor and have a look.  What I found surprised me, and so I thought I'd put this out here for the community so you can potentially avoid these pitfalls.

First let me start with the obligatory warning about working inside of CRTs.  I recommend you not do what I've done. If you do decide to go ahead, then watch a video or three about how to properly discharge a CRT before you work on it.  OK now that that's over with...

First, it was pretty easy to tear down the monitor, but I did make a mistake along the way removing the stand from the bottom of the monitor.   You don't need to do that, and if you do release the tension on the monitor stand's hinge, it's difficult to get that back in adjustment, so I'd recommend that you not remove the stand or mess with the hinge.

The back comes off with four Allen screws...

This exposes the old school RF shielding.  I'd recommend putting this back on when you are done (I'm looking at you Adrian Black).  The shielding is held on by four screws on one side and five screws on the other, they are all the same length.   When they are off, the housing comes back just a bit to release from some tabs, then can go straight up off the monitor...

This exposes the entire CRT and both boards.  Now would be the time to discharge the CRT if you were following along, which of course you are not because this is dangerous...

The main circuit board cover the back of the monitor, but the sound board is on the bottom of the enclosure.  It cannot be removed without taking the electronics off the chassis, but this is pretty easy to do.  

On the bottom of the monitor, there are two large screws that hold the electronics portion of the chassis onto the sub-frame that holds the tube and the stand.  Removed these two screws...

Disconnect all the cables from the tube, including the high voltage, the yoke, and the tube socket at the end of the tube.  Once they are disconnected, the rear of the chassis with the electronics on it can be pulled straight back.  It may be easier to pull it back just an inch to get your hand in to remove the socket from the end of the CRT.  Once all the wires are de-routed the electronics are more accessible...

The large circuit board must come off the back first before the connector board with the sound circuit can be removed.  There are two connectors going from the large board on the back to the small board on the bottom, remove those.  There are five screws holding it in.  Remove the screws and set the large board aside.  Note:  I did a careful inspection and some cleaning on this board, but I did not see any of the small electrolytic capacitors on this board, so I didn't do any recapping on this board at this time.

The small circuit board is held in by two screws inside, and two nuts on the outside of the enclosure where the cable attaches, remove those...

The circuit board has a Dozen (12) Electrolytic Capacitors. They are 47uF, 16 V rated caps...

Remove and replace the caps.  In this case the monitor was from 1991 and so it was suffering from capacitor leakage and needed some minor rework on a couple of the traces.  I'm glad I caught this in time.

But, there was one more twist in the story.  When I tested the monitor, the audio was not restored to function.  After measuring resistance on the speaker, it was open circuit.  I was able to source a replacement speaker from Rob at Black Hole, Inc, and the monitor and speaker are now functioning normally.

The final hardware upgrade I'm planning for this machine is to replace the Spinning HDD with a Solid State device, but in the meantime I've got alot of learning to do about how this machine works and what its capabilities are.

It's a Unix System, I Know This.

The title of this article may be a bit misleading as the young lady in Jurassic Park probably knew more about A/UX than I did when I started this project, but it's been a fantastic learning experience and I thought I'd share some of the ups and downs along the way in case other beginners experience similar struggles getting A/UX installed on actual hardware.

I became aware of Apple's first foray into the world of Unix within the last few years.  I was not a Macintosh user at that time, or a Unix user, as I had a PC and my college had DEC VAX systems.  As usual with my experiences in Retro Tech, I started by watched several YouTube videos about the process of installing A/UX.  The Penelope A/UX site has also been an extremely useful resource.  The idea of exploring an earlier *NIX than any I'd ever used before sounds intriguing to me as I learn about computer history.

After reading the hardware compatibility pages from this site I started thinking about which of my Beige 68K macs were compatible.  When I started the project I had only one option from the list, a Macintosh IIsi.  As the project progressed I came into enough parts to build a IIci system.  The site does warn that a IIci is underpowered for the final version of A/UX but as I didn't have a compatible '040 system at this time I decided to forge ahead with the best hardware I have and version 3.x.

The IIci I am using has been built up from one machine that was saved from recycling by my friend John, and two machines I bought from another friend.  The case parts were cleaned and the logic board was recapped.  I won't go into too much detail about my restoration process because it was rather routine, although I must say that I have not yet been able to get the Motherboard from John's machine working, as there was quite a bit of corrosion on the board.

The Specs of the machine are:

IIci w/ Cache Card
32MB RAM
Asante MacCon PDS Ethernet Card
Blue SCSI HDD Replacement

Another requirement for installing A/UX is an Apple Compatible CD-ROM drive from a short list of compatible hardware on the list at Penelope A/UX.  This was something I had to wait and watch for a while.  I was able to harvest an internal 12x Apple CD-ROM out of a PowerMac that was headed for recycling and I also came across a TASCAM branded External CD-ROM drive w/ a TEAC drive in it.  I drive swap placing the Apple drive into this enclosure and get a working "Apple" External CD ROM.  It doesn't look authentic and the SCSI ID and termination are fixed inside the drive, but the price was right!

Once I had the hardware collected getting the software burned to CD was a challenge.  Most of that struggle was due to user error on my part.  I downloaded the CD disk image and burned it multiple times from multiple sources before realizing that I needed to rename the toast image file extension to .ISO before Mac OS would burn it to CD properly.  Once I had a working Boot Floppy and correctly burned A/UX CD, I was off to the races getting this installed.

One interesting quirk I noticed with my setup is that the CD was not being recognized on the initial boot from floppy.  I inserted the CD into the machine before it booted up and when the A/UX boot floppy completed booting, it would not recognize the CD.  I had to eject and re-insert the CD after the Floppy had fully booted, then press the retry button before the installation process would recognize the CD.

I read that the maximum partition size for a bootable A/UX partition was 2GB, so I used the standard 2000MB blank drive image from RaSCSI that is recommended for Blue SCSI, however, using this partition size resulted in some drive write errors and a corrupted partition.  After that failure I moved back to using the 1000MB blank drive image which seemed to install just fine.  I can add additional space on other SCSI IDs afterwards if 1 GB is not enough for the tools I'd like to install.

After installing the Base OS and all the Extras off the 3.0.1 CD, I then moved on to the 3.1 updates.  The A/UX system is now up and running on my Macintosh IIci...

In the future, I'd like to get TCP/IP running on this machine, but I"m waiting for a part for that, as the AUI is too thick to reach inside the narrow slot openings on the IIci, I'll have to build an adapter with a male and female DB-15 connector to extend the AUI port from the card further out of the Mac's case.

This is currently my oldest *NIX system, so I'll have to go back and brush up on System V.  Time to pull UNIX in a Nutshell and Essential System Administration down off the shelf, I don't think I've looked at these since the early 2000s!

Are you, or were you an A/UX user?  Let me know what your favorite things to do with an A/UX system are in the comments, or find my email address in my profile.