Old DOS Days 1

I’m working on an emulator for old dos systems, trying to let an agent play with it. Maybe let it finish some projects that I started back in the day.

By the way, I have reviewed some of my old DOS CLIPPER projects; The disk was not in very good condition, and many files were corrupted or unreadable but I was able to recover a few of them and it brought back a lot of memories.

A small change to an SGI workstation

I changed the indicator LEDs in my SGI Octane’s light bar. I chose blue LEDs and added two resistors to keep their current within a safe range.

The light bar is a narrow assembly in the front of the case. Its lights make the computer’s status visible from the outside. I wanted to replace the dead lights and give them a blue glow.

A restoration that took more than a year

I bought this NorthStar Advantage on Wallapop in 2024. The seller told me that the keyboard had a fault. But at power-on, the computer still displayed a message on the screen. As always trust in the seller’s words, was an act of faith.

Indeed, buying vintage computers is always a bit of a gamble but be prepared for surprises when dealing with vintage hardware.

Looking more closely at the drives

This continues NorthStar Advantage Restoration Part 1, with a closer look at the drive hardware and how floppy disks mark sectors.

Many computers from the late 1970s and early 1980s used 5¼-inch floppy drives. The Tandon TM100-2A is one example. These drives can become difficult to use as they age. Their radial alignment—the position of the read/write head across the disk’s tracks—can shift. If it moves far enough, the drive may not read or write disks reliably.

This continues NorthStar Advantage Restoration Part 2. This time, I focus on replacing the keyboard’s foam pads.

I had to wait three months for the replacement foam-and-foil pads to arrive. The first package was lost in transit, so I had to reorder them, which added to the delay.

Once they were in hand, I could proceed with the restoration work on the keyboard.

The replacement pads

There are not many places that sell these specific foam-and-foil pads, so finding a reliable source is important.

This continues NorthStar Advantage Restoration Part 3. This time, I am making 5¼-inch drive cases and fitting Gotek replacements.

Making a case for the drive bays

The NorthStar Advantage has two drive bays, and I want to use them with a Gotek floppy-drive emulator. A Gotek is a device that can stand in for a floppy disk drive. It uses a USB flash drive to provide disk images instead of physical floppy disks using a USB stick.

Bringing a QVT terminal to life on Linux over USB serial

Vintage serial terminals are simple when everything matches, and maddening when one setting is off by a single bit.

Recently, I got a Qume QVT-119 Plus terminal working as a serial console on Linux. The terminal is connected to a Raspberry Pi via a USB-to-serial adapter, and the Pi is running agetty to present a login prompt on the terminal.

SGI reanimator is a tool for restoring and managing SGI IRIX systems. It provides all necessary tools to install IRIX. (bootp, tftd end the CD images, yeras ago I did it tio install linux on a sun sparcstation ultra and it was a pain to get it working, so this is a great tool)

SGI Reanimator

# hinv
Autoload=Yes
console=g
diskless=0
dbaud=9600
volume=80
sgilogo=y
autopower=n
monitor=h
netaddr=192.168.1.105
eaddr=08:00:69:0b:83:e1 
boottune=1
ConsoleOut=video
ConsoleIn=keyboard
SystemPartition=xio(0)pci(15)scsi(0)disk(1)rdisk(0)partition(8)
OSLoadPartition=xio(0)pci(15)scsi(0)disk(1)rdisk(0)partition(0)
OSLoadFilename=/unix 
OSLoader=sash
gfx=alive
Kernname=ide 

I’ve modified my reanimator config to use the following settings to use it from my home network:

I recentrly bought a broken BBC Diskdrive and a Watford DFS disk controller card, to try to repair it. The disk drive is a dual 5.25" disk drive, and the controller card is a Watford Electronics DFS (Dual Disk Filing System) card version 1.54T.

The unit comes with two different disk drives, a Mitsubishi MF503A and a Mitsubishi M4853-342MG. Each drive has a switch on the front panel to select between single-density (40 tracks) and double-density (80 tracks) operation.