New Experimenter build - keyboad question

[Geoff Healey]

Hi, I guess this has been raised before but I have a couple of keyboard questions. I have tried 2 different wired USB keyboards without success. I see there is a list of compatible keyboards but those are not readily available in Australia and I wonder if I might have another problem. I hope to avoid buying a new keyboard if possible.

Would I expect the caps lock light to illuminate with a USB keyboard? Mine does not.

In another post I saw that the led on the front of the VT100 board will flash with activity. Is that the green led you can see when looking at the rear of the unit? That lad is on and doesnt flash. All the wiring and soldering looks good so any suggestions would be much appreciated.

[Geoff Healey]

I should have added the output via the VGA port is working OK. I have just disassembled it, re-soldered all the joints to be sure all is OK, checked the resistors are all the correct value. I also used a magnifying glass to check for shorts. The activity LED is on but permanently with no change in status with any keystrokes. I am wondering if there is any other way to check the USB port. As I wrote above I have tried 2 wired keyboards but they are of a similar (recent purchase) age. 

[Tom Cronin]

If I recall correctly, the keyboard needs to be just a USB keyboard. Some have a built in hub for other features which will confuse the VT100 terminal board.

If you have a windows computer you might try opening the device manager and particularly opening the usb tab on this and then plug in the keyboard into the windows pc. If anything new shows up besides just a keyboard I think this'd mean the keyboard has an internal hub.

I’m using an Amazon basics keyboard with mine and seems to work well (after I fixed one solder joint)

Tom

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[Geoff Healey]

Hi Tom, a new USB hub does come up. Looks like I will need to go keyboard shopping. Thank you for the tip.

[Chris Davis]

Thanks Tom, that's a great way to test keyboards.   I'll write up something about that for the website.

Geoff - I've had luck with the cheapest of keyboards - like $3.99 units.  Otherwise does the output from the VT100 emulator work?  The copyright text should display on the monitor, and pressing down on the AUX1 toggle should show a list of available built-in programs.

[John Galt]

on top of finding a keyboard that isn't a hub,, some usb keyboard have different key mapping and then some keys don't work like the pipe key. 

i bought a bunch of different usb keyboard i found a bunch of USB HP keyboards that worked off amazon.

[Flavio Villanustre]

And this suggestion may sound retro, but hey! We are talking about retro-computing here :)

If you have a PS2 keyboard and a USB to PS2 adapter, that keyboard is almost guaranteed to work (the old HP keyboards are a good example). Not that I necessarily recommend that you do this, but if you have one of those keyboards at home, this could be a simple and inexpensive solution.

Best,

Flavio

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[Richard Deane]

My own experience is that scan codes from a PS2 keyboard are not the same as Microsoft USB scan codes (even when through the adapter to PS/2) This gave me some grief creating a UK keyboard layout for Kurt Mueller's Multicomp.

Another "gotcha" is the Menu key (rhs of space  bar -  needed to invoke menus on the Windows Joyce Amstrad PCW emulator - not all keyboards work well at that, my two Coolermaster keyboards fail at that.

Also not all PS/2 keyboards work at 3.3v supply which several Multicomp systems have.

Richard

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[Geoff Healey]

Hi Chris, yes the copyright message and AUX 1 and AUX 2 list of programs are listed. Is the activity led on by default? Mine is lit with no flashing.

Ill see if I can find a couple of bargain ones today.

Thanks for the advice.

Geoff

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[Chris Davis]

The activity LED will flash when data is received by the VT100 emulator.  That includes data from the keyboard, or data from the Altair-Duino.  If you lower the AUX1 toggle, you should see the LED flash once for each byte received (so it will flash rapidly).  If you're not seeing it flash when pressing a key on the keyboard, then that keyboard is not compatible.  

[Geoff Healey]

Yes the LED flashes when the menu is displayed so it is the keyboard.

Thanks again for support.

Geoff

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[Geoff Healey]

I am wondering if I do have a wiring or other error on my board. I have tried 3 USB keyboards from the cheapest available and 2 x PS/2 keyboards. The activity led flashes when the menu's are displayed and solid on  as the default status. I am hoping there are any tests I can do with the USB port (other than a keyboard) to test that it is functioning. I ask because none of the listed keyboards are available in Australia, the shipping is expensive and I am worried if there is a problem at my end it wont solve my problem. 

[Geoff Healey]

Would something like this be a solution for PS/2 5v requirements https://sensorkit.joy-it.net/en/sensors/ky-051

[Chris Davis]

The page with a few keyboards is not an exhaustive list of keyboards that will work with the VT100 emulator.  It was actually meant to just be a list of mechanical, or "retro-looking" keyboards.  The truth is most basic USB keyboards will work with the emulator.  Just as long as it does not have an internal USB hub.

There is very little circuitry between the PIC32 microcontroller and the USB jack.  There is only a single resistor (the 4.7k).  I have attached the schematic diagram.  Check for 5v on pin 1 of the USB connector, then check for continuity on pin 4 to ground, pin 2 to pin 22 of the PIC 32, pin 3 to one end of the 4.7k resistor, and the other end of the resistor to pin 15 of the PIC32.

Then check continuity from the VT100 emulator board to the connection point on the main circuit board (5v, 3.3v, D18, D19, and GND).  Also check for cross-continuity on the six pins for the six-pin ribbon cable connector, in case there is some hidden solder bridge under the six-pin connector to the VT100 circuit board.

Based on your description of behavior, I would be strongly suspect of the 5v line (since it has one purpose - to power the USB keyboard), or the D18/D19 lines.

I would not spend any time messing with PS/2 keyboards.

[Chris Davis]

Sorry, I forgot the attachment.

[Geoff Healey]

Its now working fine, thank you for all your help.

[David Brunell]

Geoff, what did you do to finally get a working keyboard? I have so far only found one keyboard that works, one which I'd rather not use as it's crappy. None of these keyboards has a built-in hub, judged by how they enumerate on the Linux OS.

The one keyboard that I did get to work is a dual-mode PS/2-and-USB keyboard. A little history here... When USB was first introduced, many keyboard manufacturers produced dual-mode keyboards that would auto-detect whether the attached computer had a PS/2 or USB port. The onboard microprocessor would then activate the appropriate interface in its firmware. These keyboards were supplied with a passive PS/2-to-USB adapter, which was really just a pass-through connector without any logic of its own.

I assume that the code loaded onto the PIC processor is this: https://github.com/dhansel/TerminalUSB/tree/master. It is clearly looking for a USB HID device and not a PS/2 keyboard. The puzzling part is why it works with these dual-mode keyboards and not modern keyboards which have dropped all the dual-mode code. There may be more advanced HID negotiation protocols used in newer keyboards that the code doesn't recognize.

Even in this one keyboard that works, the backspace key is oddly not recognized.

[John Galt]

I ended up having to use a ridiculous RGB USB keyboard that the Geoff terminal liked. 

I was so annoyed with it that I bought a bunch of keyboard stickers that glued on top of each key to block out most of the RGB coloring.

after a few months i migrated to a completely different terminal that uses PS/2 and i could use a normal HP keyboard.

[David Brunell]

I did some more testing of different keyboards and found another one that works, but with the same backspace key issue. Both of the keyboards that work use older controllers. My working hypothesis at this point is that the Microchip PIC HID library is janky/obsolete. I might be able to fix my backspace problem by messing with the key maps in Keyboard.c.

There seems to be a recurring theme in retro computing circles of problems with terminal boards. Either they are really fussy with keyboards or the video quality is marginal or it's hard to find a monitor with the right aspect ratio that doesn't over/under scan. My long-term solution is to make a terminal using a Raspberry Pi Zero, which should work great with just about any keyboard or monitor.

[Chris Davis]

Don't automatically assume there is a "backspace key issue".  Back in 1975 the backspace was not a guarantee.  Much software used an underscore as the rubout character.  For example, MBASIC in CP/M will let you use the backspace key, but MITS 16k ROM BASIC (raise AUX1 to launch) required you to use the rubout character.

[David Brunell]

Ah yes, so true! I was using the MITS ROM BASIC for testing mostly. Ctrl-H, ctrl-G, etc. were also used in some programs. And then there are the variations on what is expected for newline and break. I see switchable key maps coming in handy here.