2 sio

[Geoff Harrison]

Originally Posted by marty

I noticed that above ic's K and M You do not have pin 4 wired along with 1 and 2

Yes, I brought out only the Tx & Rx lines and left RTS, CTS, & DCD disconnected. To keep the 6850 happy I tied pins 23 & 24 to ground.

Originally Posted by marty

The board still passes the echo test, but will not download correctly.... it is at 4800 baud... I can slow it down to 300 baud, and just try the second stage loader. to see if that helps.
Any Ideas ??????

I think it's worth taking it down as slow as you can drive it (300, even 110) to see if you get anywhere.

When you run the echo test and hold down a key to send a stream of characters, does it echo correctly or does it garble or miss characters?

If you're using TerraTerm to send the paper tape image, try setting an inter-character delay. I don't remember if HyperTerm lets you do that too.

When the Altair is running the loader waiting for you to send the tape, the address and status lights should show a steady, unchanging pattern. Then when you start sending the tape, the lights should change to a different pattern and flicker slightly, though it may be pretty subtle. If the lights never change from their original pattern, my guess would be that the 2SIO is not receiving a full 8 bit data stream. If the lights do change then the loader found the start token, if it has trouble after that it will generally print some sort of error code.

What loader are you using and what are you trying to load?

Originally Posted by marty

You are becomming the Sio Man

That might be a case of the blind leading the blind.

Geoff.