88-sio 7e1 terminal

General discussions related to the Altair 8800 Clone

88-sio 7e1 terminal

Postby Ben_Aveline » February 8th, 2023, 8:07 am

Hi,
First let me quickly introduce myself, as I am new here. I'm Ben, french developer, retro-computers enthusiast. I spent a year building then studying an Apple-1 replica. And I'm now focused on the Altair 8800. I recently acquired one of Mike's wonderful clones.
Now let's talk about my issue; I have a terminal I wish I could use with it. It's a Matra Minitel 1b (old french tech, but basically, juste a dumb terminal but with a modem included). It has a tty input (din5) so I mounted a small rs232 to ttl on a din5 jack. I plugged it to a usb db9 rs232 cord, and setup teraterm for 4800baud, 7e1 bits. I can use my computer to type on the terminal, and the terminal to type on my computer. Great.
Then I changed the altair 1st connector to the same settings (88-sio 7e1 4800b), and used the front panel to enter the SIO echo test. Works perfectly. So far so good.
But then, I can't boot any floppy to show up to the terminal (tried the 3 pre-loaded floppies).
I noticed the same settings with teraterm do the same: nothing shows up.
I'm sure I'm missing something, and the operator's manual says the connection should use 2SIO settings but I'd like to understand why, and how it can be changed (if it can).
Thank you

Ben
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Re: 88-sio 7e1 terminal

Postby AltairClone » February 8th, 2023, 10:23 pm

All versions of CP/M for the Altair expect a 2SIO port for console I/O. Track buffered CP/M (CP/M 2.2b) supports IOBYTE and the SIO can be selected as the console serial port, but you’ll have to boot first with a 2SIO and then follow the instructions in the ReadMe file below to patch the IOBYTE for the SIO serial board as console for the next cold boot.

https://altairclone.com/downloads/cpm/C ... ReadMe.pdf

Altair DOS and Altair BASIC can use the SIO as the serial port but you have to specify the SIO on the front panel switches before depressing RUN to boot the disk. For example, set A15-A12 to 0010 after examining FF00 to select the disk boot loader to boot Altair DOS or Disk BASIC with an SIO as the console serial board.

Mike
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Re: 88-sio 7e1 terminal

Postby Ben_Aveline » February 9th, 2023, 8:14 am

Ok thank you very much. It appears that the 0010 settings was all I was missing. Now I can use BASIC on my old Matra 1b Minitel. Thank you again.
Ben_Aveline
 
Posts: 10
Joined: February 7th, 2023, 3:24 am


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