Your Home Mainframe

Your Home Mainframe

Time Stamp: December 29, 2023 1:00 AM
Source Node: 2418624

We miss the days when computers looked like computers. You know, blinking lights, rows of switches, and cryptic displays. [Phil Tipping] must miss those days too since he built PlasMa, a “mini-mainframe simulator.”

The device would look at home on the set of any old science fiction movie. Externally, it has 540 LEDs, 100 switches, and a number of other I/O devices, including a keypad and an LCD screen. Internally, it can support three different instruction sets. Everything is run by an ATmega2560, and it has simulated paper tape, magnetic tape, and disks (all via SD cards). The magnetic tapes also have LED simulated reels to show the tape position and other status information (the round displays just above the LCD display).

One of the CPUs has a 64K address space and floating point capabilities. You can see the floating point used with a lunar lander example in the video below. We would love to see a virtual IBM 360 done like this, but then you’d get into making it look right, and since PlasMa is its own machine, you can make it look any way that you like. Sure, you can run Hercules as a simulator, but having all the switches and lights would make it that much better.

If you fancy building your own, there is a complete guide, but it probably isn’t an afternoon project. Inside, there are multiple PC boards, each containing a different system. According to the build document, you could create a subset system by using only some of the boards.

If you just want your own mainframe, you can easily do software simulations, of course. If you find front panels intimidating, maybe start with an easier one.

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