Frequently Asked Questions

This is really weird! How can I cancel a mistyped character? The S2 key does not appear to behave like a normal backspace!

When the M20 was made, it was not obvious that the top right key (labeled S2 in the M20) would be a backspace. To cancel a mistyped character, you should type CTRL+H. At the time, several CP/M computers shared the same idea and in typewriters the backspace was even harder to obtain... Anyway, you can redefine the S2 key in order to behave like a backspace using the PCOS command ckey in the following way: ck &C3,8

I just found an old M20. I managed to find a PCOS, but I do not know anything about the configuration of the computer.

If the PCOS version is at least 2.0, you can type dc %h or dc %m to obtain informations about hardware installed and the memory configuration.

I am writing a program using the BASIC and I have an M20 with an Italian keyboard layout. I want to copy a listing from an English manual, but I do not know how to enter the symbols @ and #.

Nationalized versions of M20 use a slightly different character set. In the Italian case, the symbol corresponding to @ is the section sign § (a sort of S with a small circle inside), that you can use at the place of @. For the #, the equivalent is the £.

I started using the M20 and I found somewhere the PCOS disks. All is OK, but the keyboard layout does not appear to be correct. Is there a way to define the keyboard layout?

Yes: type sl and you will be prompted for your keyboard language.

I see that the M20 supports a 80x25 text video. How can I switch from the default 64x16?

Type the PCOS command ss ,,,,1

I have found an M20, but the monitor is absent/non-working. What can I do?

Well... It's a problem. The M20 uses an horizontal sync frequency which is not accepted for example by PC CGA monitors. Maybe it is worth trying (at your own risk, as you can blow it) with a EGA multi-sync, but results are not certain. Anyway, you can build a RS-232 cable and control it with a serial connection and using a terminal emulation program. Have a look on this page. You need to boot your machine with a PCOS disk and then type (without seeing)

sc com:,9600,none,0,8,half,off,256
ci 0,o,0
+Scom:, +Dcom:

The first line configure the onboard RS-232 interface for a 9600 baud 8N1 connection, without echoing nor XON/XOFF control. You need to configure your favorite terminal program in the same way. The second command opens the serial connection, while the third line permanently redirect all outputs on the serial line, which is used also as an input string. Make sure your keyboard layout is correct. If all is OK, you should see the PCOS prompt on the terminal.

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