Legacy Pixels VT100

[Peter Sterrantino]

Hi All, 

Finally got around to setting up the legacy pixel VT100 I got back on March 25 (thru eBay). But I think I have a problem. 

I receive characters from the serial port on my IMSAI just fine (I get the ALTMON prompt on my display ) but when I type, I get nothing…. No response at all. I’m convinced the keyboard works as it works with the screen setup. 

Is there any reason that I would be receiving characters but not sending characters? 

I double checked using teraterm and my laptop setup and my serial card is working fine.

Also seeing the rx and rx leds on the legacy pixel board, but nothing on the screen.

Any suggestions? Thanks.

Pete 

[Mike Douglas]

Sounds like the VT-100 needs to see CTS from the IMSAI, or jumper it locally on the legacy VT-100.

Mike D

[Peter Sterrantino]

Hi Mike, 

I'll try that. After writing the initial post, I realized It worked previously when I first got the VT100 back in April, but back then I was using my Interfacer 1 card. Since then I switched to Patrick's 88-2SIO card, which is where I'm seeing this. 

I was going to try swapping back to the old Interfacer 1 setup to see if that still works but I'll try the CTS jumper first as that is simpler... 

I probably should also check the CTS disable switches on Patrick's 88-2SIO board to see if those are inadvertently disabled.

Thanks!

Pete

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[Walt Perko]

Hi,  

Maybe you only need to enable the CTS on the 88-2SIOR1 board ... the little 4-position DIP switches set that:  

.

[Patrick Linstruth]

The 2SIO (6850 ACIA) disables the receiver if DCD is not active. The “Disable DCD” switch on the 2SIOR1 disables getting DCD from the RS232 and forces it active at the 6850.

If you do not have DCD wired to the 2SIOR1 through your serial cable, turn /DCD switch ON.

The 2SIO also disables the transmitter if CTS is not active. The “Disable CTS” switch also forces that control signal active when ON.

I should have labeled those switches “FORCE CTS HIGH” and “FORCE DCD HIGH”.

On May 17, 2026, at 11:09 AM, Walt Perko <r4r...@gmail.com> wrote:

Hi,  

Maybe you only need to enable the CTS on the 88-2SIOR1 board ... the little 4-position DIP switches set that:  

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<20250523-88-2SIOR1C SN 0026 Front-R2K-T.jpg>

[Peter Sterrantino]

Hi Patrick, 

Thanks for the info. Those two switches did the trick. 

Pete 

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