I recently got a new text only CRT (I get it, its retro, I like it). I run minimal, tty only, CentOS 7. I need to disable all color system wide (monitor only does green, so I cant see some stuff). Any help?

Also, the text is like one or two lines too long for the display, and like 10 characters too wide. Help?



If it's not a CRT monitor connected to a VGA port, most serial terminals (that haven't died just yet or spontaneously decomposed by now) have a 132 column mode. That should solve your width issue (people these days no longer design software for 80-column screens).

As for the colors, what other terminals you have defined? vt-100 was a popular standard and most physical terminals can do that. If yours can't, you are going seriously vintage here.

Edit: since you are piping a normal text console through composite, I guess 132 columns will make it hard to resolve the pixels, so the layout thing may be a hard one to get to. The width can be probably tweaked with the horizontal offset usually on the back of the monitor and the horizontal size, usually inside the monitor (careful - high-voltages lurk inside, respect your CRTs). Some monitors of the time had a switch that added a bit of the chroma signal to the luminance channel before modulating it through the electron gun, so you would have different shades of grey/amber/green for different colors, even if they all had the same luminance levels. Not sure about the Amdek (cool choice, BTW).

If none of that works, you may need to change the VGA palette itself to send luminance values that are not the default VGA ones (where luma defaults to the number of high bits on the RGBI palette). Luckily, the Linux kernel has three handy vt.default_* kernel paremeters that take each 16 1-byte values for the RGB component of each of the 16 console colors. From the kernel docs:

    vt.default_blu= [VT]
                    Format: <blue0>,<blue1>,<blue2>,...,<blue15>
                    Change the default blue palette of the console.
                    This is a 16-member array composed of values
                    ranging from 0-255.

    vt.default_grn= [VT]
                    Format: <green0>,<green1>,<green2>,...,<green15>
                    Change the default green palette of the console.
                    This is a 16-member array composed of values
                    ranging from 0-255.

    vt.default_red= [VT]
                    Format: <red0>,<red1>,<red2>,...,<red15>
                    Change the default red palette of the console.
                    This is a 16-member array composed of values
                    ranging from 0-255.

Telling the kernel to boot with "vt.default_grn=0x00,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff" got my text console a nice green tint. You'll need to fine tune the values yourself (most of my own vintage stuff is in Brazil, as it's horrendously expensive to ship it here, and, even if I did, I never had an cool Amdek 300, you lucky guy ;-)).

  • I've got an AMDESK Video-300 (For apple II). I have it connected to a HDMI port on my GTX 1080, going through a HDMI to composite adapter (I have learned to hate China post shipping) – Eric Jan 3 '18 at 17:03
  • And yes, before you ask, I do also have a 9-pin dot matrix impact printer, and IBM model M keyboard. You may wonder why I have such retro hardware hooked up to my desktop (I built it in a retro case with an AMD Ryzen 7 1700, dual RAID 0 SSDs, 32GB RAM, and GTX 1080). I just happen to love a retro look and feel with full modern functionality. – Eric Jan 3 '18 at 17:20
  • I don't wonder. I have an IBM 122-key "battleship" on my desk and my favorite font is an IBM 3270 recreation I made (github.com/rbanffy/3270font). I grew up starring down the barrels of electron guns. ;-) – rbanffy Jan 6 '18 at 12:44
  • BTW, for the extra vintage feel, adding vt.cur_default=8 will give you a block cursor, which is how God intended cursors to be. – rbanffy Jan 6 '18 at 14:38
  • Sorry for the delayed reply, but my hdmi to composite adapter died a horrible death, so I had to wait for the replacement to ship in. I'm wondering where you set those kernel parameters (vt.cur_default=8; vt.default_grn). Did you set them in the GRUB cfg file, or what other file did you use? – Eric Jan 9 '18 at 23:23

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