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Blinky light panel for PC

legalize

legalize

Experienced Member
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Mar 24, 2006
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391
Location
Salt Lake City, UT, USA
Has anyone ever made one?

I was thinking:
  • 64 LED bar/lights for PC
  • 64 LED bar/lights for basic registers:
    • {{{{al, ah}, ax}, eax}, rax}
    • {{{{bl, bh}, bx}, ebx}, rbx}
    • {{{{cl, ch}, cx}, ecx}, rcx}
    • {{{{dl, dh}, dx}, edx}, rdx}
    • {{{{bpl}, bp}, ebp}, rbp}
    • {{{{sil}, si}, esi}, rsi}
    • {{{{dil}, di}, edi}, rdi}
    • {{{{spl}, sp}, esp}, rsp}
  • flags registers
  • segment registers?
  • bank of register displays with a rotary switch to select between MMX, XMM, YMM, ZMM
  • bank of switches to load a register

(See register diagram on wikipedia)

The idea is not that this would give you "run/halt" ability of your PC, but that while you were stepping through code in a debugger, you could examine and modify registers in the debug target while stopped. The panel would connect via USB, look like a COM port and there would have to be some sort of debugger extension to interact with the device through the COM port. It would be tedious to solder up, but not particularly difficult.

Thoughts?
 
A keyboard and a monitor does the job quite well, don't you think?

Many classic computers lacked any sort of front panel. They did just fine.
 
Never made one, no reason why you couldn't. Any number of microcontrollers would do the job. I would of course use a high pin count PIC :)
 
Having implemented a few monitoring boards for my Z80 computer, I find blinky LEDs aren't very practical and I get bored with them quickly. It's too much mental work for me to think in binary. I prefer hex displays. You can source some TIL311s on eBay, or use something like a serial vacuum fluorescent display to give a retro look. The VFD has the benefit that when you get bored with displaying CPU state on it, you could use it for other runtime information.

My current retro-PC case is designed to accommodate one of two acrylic front panels. One of them has eight IN-12 Nixie Tubes. The other has a footprint for a 4x40 VFD. The front panel will be interfaced to an 8255.
 
What's wrong with a nice backlit LCD or OLED?

I"m having a lot of trouble with this--professionally, the last machine I worked with that had an honest to gosh gotta-use-it front panel was a S/360 Model 40. After that it was either an integrated CRT display or MCU or nothing--and that was more than 40 years ago.

For personal computing, I ditched my MITS 8800 for a blank front-panel Integrand box and PROM monitor and didn't miss the LEDs. Even if you look at the front panel of an Intel MDS 800, there's not much there--and that was Intel's professional development system.

Even debugging MCU code today for me usually involves a serial connection to a PC running terminal software. No blinky leds.
 
smbaker said:
Having implemented a few monitoring boards for my Z80 computer, I find blinky LEDs aren't very practical and I get bored with them quickly. It's too much mental work for me to think in binary. I prefer hex displays. You can source some TIL311s on eBay, or use something like a serial vacuum fluorescent display to give a retro look. The VFD has the benefit that when you get bored with displaying CPU state on it, you could use it for other runtime information.
Click to expand...

Yeah, ok, single bit indicators get a little tedious with the >= 64 bit registers. I like hex displays. I like VFDs even more! I wouldn't want a flat screen, that's boring and not retro enough. If I'm going to do a flat screen, I might as well just use the existing monitor. I still like single LEDs for the bit flags in the PSW. A run/stop and single step toggle (gdb 'continue', gdb 'step') could also be nice. Perhaps even a VFD single line 40 character display showing disassembled current instruction near the stop/run/step switches.

So if there are hex displays for registers, that implies a hex keypad for setting the contents of the register as well.

For brains, you'd want a system-on-a-chip microcontroller with built-in USB and a sh'load of I/O pins. Still might need to do some muxing depending on pin count, but with hex digit displays it should be good enough. I imagine that there are daisy-chainable hex digit displays with I2C or some other low pin count serial interface, so they wouldn't gobble up too many pins.
 
Okay, I guess I get your point. How about a tiny monochrome CRT?

That VFD has characters that are less than 0.25" tall. Sort of what you might see on old credit-card terminals.

Maybe your best bet might be the 16-segment LED displays from AliExpress $15 for 20 isn't such a a bad deal--and you can get them in green or red.
 
Last edited:
Tiny CRT? Interesting idea, but feels like overkill and too close to the existing monitor.

Yeah, segmented LED displays for the digits of the registers. Rotary switch to change banked display for sets of extended register files. Individual LEDs for bits in the PSW. VFD for disassembled current instruction, run/stop switch, single step switch, hex keypad for data entry and register selection. Maybe I can mock something up in fritzing.
 
LEDs, VFDs, 7-segment (or 14 segment?) displays, rotary switches, hex keypad... I think you need to add a speech synthesizer too, to announce when the current program is breakpointed, stepped, or a significant fault occurs.

"Division by Zero Error.
CPU Halted"
 
Reminds me a bit of the Nixie bar graph display that I saw on a system under development at the Phoenix (used to be GE) Honeywell plant around 1973. The same console had all sorts of indicators on it, including 4 CRT displays. It was interesting to watch. This was a direct water-cooled computer--chilled water was circulated through the system with copper diaphragms serving as the interface between the water and electronics.

While you're at it, why not an analog meter displaying thousand operations per second?
 
I had ideas about building a console with a multitude of video camera viewfinder CRTs someday when they got cheap due to the switch to LCD/etc. , mind you not for a PC front panel. But the window of time when such CRTs and support circuitry were dirt cheap, I was in a spending freeze, and the window lasted much less than I expected. So it just wasn't meant to be.
 
smbaker said:
LEDs, VFDs, 7-segment (or 14 segment?) displays, rotary switches, hex keypad... I think you need to add a speech synthesizer too, to announce when the current program is breakpointed, stepped, or a significant fault occurs.

"Division by Zero Error.
CPU Halted"
Click to expand...

You can probably wire that up through the debugger to the PC's audio device.
 
David_M said:
If you want to go the 7 segment LED route... 8 digits and only uses 3 IO ports on a microcontroller for a couple of bucks so you can afford to have one for every register. You can even choose red green or blue.

http://www.ebay.com.au/itm/8-Digit-...hash=item3d298aee54:m:myGfc9Lo5iCOel-WT-gaYwQ

If you want more ports to drive single LEDs than the cheap microcontrollers offer just use i2c expander chips.
Click to expand...

That's a great idea. Unfortunately the MAX7219 doesn't display hex digits. However, the idea of using a controller IC with I2C (or similar) interface to the microcontroller for an entire register bank is a good one.
 
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