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.
Really cool! 😎
Btw, the LCD could be replaced by a little b/w CRT maybe (recent 12v camping TVs have AV in). Or a round oscilloscope tube..
But then the LED’s (especially blue ones) should also be replaced with soft warm incandescent bulbs…
Neon
+1
Reminds me of these little glow lamps.
They’re technically related to neon, I believe.
Nixie tubes !! Many had pre-shaped digits ‘0-9’ & look like neon. Search nixie tube
I played this in high school in 1972 or 73 on a Nova we loaded off paper tape. It printed on a line printer, no screen, so I remember that printer noise between answers. Once you work it out, it’s not too bad. We used a slide rule to work out burn rates and timing… I wonder if I still remember how to use one?
That would be cool. But the amperage would be a bit higher, so a stronger PSU would be needed.
An alternative would be halogen lamps, they’re more modest than normal incandescent lamps.
Or those electro-mechanical anical indicators of old rotary phones.
Halogen lamps are more efficient that normal incandescents at high power, that enables the halogen reaction inside the bulb. But not so at the indicator light level.
In my honest opinion leds have become too bright, i mean whats up with electronic manufacturers having blue standby leds that light up a bedroom when its dark😂
I bought a knockoff arduino uno, it had the standard dim light green surface mount LEDs, except for one of them… it was actually blinding to look at. A surface mount pure white flashlight LED must have gotten into their mix of substandard parts, it literally over doubled the power consumption of the board! Absolute eyesore lol.
Ah, mainframe porn…GCOS8 and an analogue indicator that would struggle to max out at one MIP..them were the days 😅
Back in 1980, older HP1000 series mainframe panels used tiny bayonet bulbs, kept slightly incandescent in their inactive state to lenghten their life span.
Good old times…
This reminds me of the tv series “The time tunnel” !
Somewhere in my junk room there is a part of a front panel from an IBM 360 with lot of toggle switches, lights and some rotary switches… but obviously not working !
Got it from my father who got it from the company he was working for when it closed.
Yes !
They were using old Borroughs equipment.
That was also on the flight deck of the Jupiter II consoles.
But Admiral Nelson’s “Seaview” was a lot cooler !
(always loved the background sound of their CIC).
Mmmm… switch pron.
Handy for building one’s evil lair.
2024. Do x86, ARM, RISC-V, … all get the same 64 bit floating point results? Using different vendors’ platforms, of course.
Does a $95 Lenovo N4020 Celeron laptop get the same 64 bit pf results as a super computer?
Same question for Lenovo <$200 Intel N5030 and AMD 7120U 2+2 cores.
Two Lenovo Ideadpad 1i N5030 4+0 cores 4/128 GB purchased from Walmart for $129.
Google search revealed the answer is 'No!'.
You were expecting the results to be the same?
Yes. I don’t understand why you would expect the results to be different. Surely the results of the same calculation to the same precision should be the SAME regardless of which CPU platform it is running on.
> I don’t understand why you would expect the results to be different.
It’s rather disappointing they don’t produce the “same” results, but it’s really due to the nature of what they are. Floating point numbers are like compressed representations of real numbers, in fact you can think of it as they try to represent an infinite number of values with a fixed number of values. This means you are loosing precision somewhere, and how this precision is discarded can create differences in results.
Either we live with differences from different implementation, or severely constrain hardware designs to always produce the same estimated (incorrect by the same amount every time) results. This stifles CPU manufactures ability to trade off speed with accuracy, or from trying to produce higher accuracy floating point implementations.
For example, consider I’m going to add and multiple a bunch of 32bit floats and I care more about precision than speed. I might build a CPU with an ALU which uses 64bit floating point internals (i.e. an accumulator or registers or something that) for storing results so I don’t loose so much precision during intermediate calculations. In the end I would still get back a 32bit float, but it should be more accurate than if my ALU had used 32bit internals. Or maybe I want to balance speed and accuracy, so I try a 48bit ALU internal representation instead. Now for the same set of identical calculations I will 3 different results depending on which CPU I run them on.
x86 platform has x87 NPU w/ 80-Bit precision, as well.
“Google search revealed the answer is ‘No!’.”
Don’t limit yourself unnecessarily!
You could get a ‘Yes!’ using ChatGPT…
Oh, God, this reminds me of a Signa 9 main frame computer I use to maintain where I worked 40 years ago. The Sigma 9 was old then. 14 racks the size of refrigerators, 2 hard disks the size of dish washers, and 2 huge tape drives with 1/2 inch real to real tape. The entire system drew 40KW when running. It was a 32 bit machine with 128K of RAM, Oooooo. It had a front panel on one of the (4) CPU racks that looked much like this front panel. Dems were the good old days.
What was it used for? Do you have any pictures that survived?
“and 2 huge tape drives with 1/2 inch real to real tape.”
Those were so much more practical than the real to ethereal tape drives we had to use back in my day! You kids don’t know just how lucky you were!
Kudos! Really cool!!!!! Real computers should have switches, lights, dials, etc. One of the reasons I got Oscar’s 1/3 scale PDP 11/70 as I can have a good RPI doing useful work behind a blinky front panel. Thinking of changing out the RPI-4 with an RPI-5 now as the RPI-5 can handle large SSDs. I also built the Star Trek 60s computer again with a RPI behind it. Yep… Really like lights and switches!
I have built Oscar’s PDP11 and PDP8 replicas, and really can recommend those! Very good quality kits and with the latest software, you get the incandescent lamp simulation also. :)
Ahh, that brings back memories! I used to program a PDP-8i back in highschool in the early 70s. Got to know our DEC service rep so well I became a service engineer myself and had a nice career servicing computers of that vintage in overseas military bases. Always loved it when all the fans turned on, the tapes spun, the washing machine sized disk drives clicked and buzzed and of course the lights started blinking. Those were fun times! You knew you’d fixed something with those machines. Today’s computers just don’t feel the same.
I have Oscar’s PDP8 replica. It’s as close to owning your own PDP8 as you’ll get. I need switches for it, though. Anyone know where I can find some miniature SPDT on-on (momentary spring return on one side) switches? My usual sources only carry on-on with no spring return types.
Thanks!
With the RPI-5s I run the 64bit PI OS . So thinking of following the instructions I ran across to get the simh simulator working. I wish both a 32bit and 64bit version were available for download directly but so it goes. I tried to get the PDP-8 last year but got no response when I sent an email so moved on…
I agree about the quality. Good kits. I did have a couple cold solder joints I had to re-solder I recall — that’s on me :) . I did make another nice flat wood base board. Also, had my son 3D print an extension/encloser (about 2″ more depth) to the back of the panel to give me more room behind it for whatever I want to add to the project. For example I boot off a USB 3.0 Samsung T5 SSD which easily fits in the back now. Also any relays/automation equipment I might want to add later to the project. Oh, and the extension gave me a good flat attachment surface to the base. Now solid as a rock when flipping switches on the front.
Oscar was sick for a while last year, if you want to retry, he might get back to you. The 8 was a very basic machine though. I used a PDP-8/I at uni many years ago. The 11 was much better.
I miss the ability to single step the processor from the panel and watch the register contents change. It is the ultimate debugging tool.
https://hackaday.com/2023/08/21/a-mainframe-computer-for-the-modern-age/
“Home mainframe”, I was expecting it to be the core of home automation.
(Slightly disappointed)
Ah, Demon Seed.
https://en.wikipedia.org/wiki/Demon_Seed
Rob Carnegie of the
Chilliwack Retro-Computing Club built an incredible looking miniature IBM System/370 Model 145 using a Z8350 SBC.
One day I’m going to build a computer like this with an Intel i5. Nothing better than 36 switches for specifying an address and another 64 for specifying the data. :) That alone already gives me a 100 switches!