4.77Mhz Web server with reasonable performance (1984 PCjr)

There was a news item recently featuring somebody running an old PC clone as a web server. I wanted to post a follow-up showing a low-end machine with a more full-featured web site.

The machine is an IBM PCjr which was introduced in 1983. The machine is an Intel 8088 running at 4.77Mhz. A jrIDE sidecar has been added to add an IDE interface and fill the system memory out. Storage is a 4GB CF card on the IDE interface. A Xircom PE3-10BT Ethernet adapter is attached to the parallel port, which has been modified to be bi-directional. The floppy drive has been upgraded to a 720KB double density drive, but that was not really necessary as the machine boots and runs from the CF card.

Software is IBM PC DOS 5.02 and mTCP. I run the HTTP server as a long term test of the underlying TCP/IP code. (Another mTCP release is due soon.) Up to eight concurrent connections are supported, but each one slows the others down as they are sharing CPU time and network bandwidth.

My router is setup to use dynamic DNS and the machine is hidden behind the router. So it is not exposed to all of the badness of the open Internet, but it still is dealing with bots probing for PHP, Wordpress and other vulnerabilities on port 80.

The machine is capable of much better performance (2x) when a proper Ethernet card is used; the Xircom is bottlenecked by the parallel port. I only have one PCjr bus-to-ISA bus adapter and I did not want to tie it up while I am working on designing a new one.

For monitoring I have it broadcasting a UDP packet for each log entry that it makes. So there is a local disk log, and I can snoop on it from another machine in the house. This lets me run it without a monitor while still being able to check on it.

The machine has been up and running over 120 hours now. If you follow the status page from the main page you can see the real-time stats, including dropped packets, objects served, etc. If you look carefully you will see that my own internal network is quite noisy and that is giving it more to contend with.

I intend to run the machine this way indefinitely, with the occasional maintenance window. I don't expect the machine to weather a DOS attack. If it stays running and does not crash that is a victory.

More details on the Reddit post: https://www.reddit.com/r/vintagecomputing/comments/uptyr1/be...

Bonus: Make the machine beep! Every time it serves an object it beeps.