M20 Olivetti M20

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

  • dc command screenshot
  • 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 information about hardware installed and the memory configuration. Looking at the inside of the machine, you should be able to see if there are memory expansions installed. There were 32KiB or 128KiB memory expansions available on three slots. Two kinds of expansions were available for each size: color or B/W machines. Several jumpers have to be configured for each memory size. If the configuration is incorrect, expect to see a diamond at startup. You can also see if there is a hard disk installed (it requires a controller board) or if some special expansions are present in your system. Common ones are the IEEE interface and the APB 8086 (that allowed to run DOS). Disk drives may have a slightly different profile if they are 640KiB, 320KiB or 160KiB ones.

  • 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.

  • An M20 with a MDA monitor
  • 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. 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.

    The Tulip MDA monitor used by Retro Nora

    Retro Nora suggested in a Twitter conversation that an MDA monitor can be used with a proper cable. Just be careful! MDA HSync is 18.43kHz whereas the M20 B/W video uses 18.73kHz. The difference can create problems (and even smoke!) on some monitor, but some can cope with it (tweaking the sync trimmers on the monitor). Be careful if you try this! The monitor used by Retro Nora is a Tulip and uses a non-standard pinout. Be very careful to build your own cable. The original M20 monitor requires 12V to be powered and this voltage is present on the back of the M20 video connector. If you mis-wire it you can easily fry your MDA monitor.

    Another possibility is trying to find a compatible Olivetti monitor, such as the DSM1219, but they may be even rarer than the M20!

  • How much is an M20 worth?

    It is impossible to answer to such a question. When the computer was new, the answer was "much". Then, for a long period, the only possible answer was "zero", but now things differ. If you want to sell one, keep in mind that there are some enthusiasts that truly love the machine. If the alternative you have is to keep it dusting in a storage box, please do not think you are going to become rich with it.

  • I have a working Olivetti M20. What can I do, now?

    Even if much of the software available at the time was dedicated to running a small business, it is unlikely that you want to use your M20 for your administrative chores. You can run some games. If you like text adventures, there are a few running on the system. You can also use it as a glorified typewriter. The absence of distraction is pleasing: no notification from social networks will appear on your screen while you are using Oliwrite.

  • Are there easter eggs in the M20 firmware?

    Yes, in some versions of the firmware (greater than 1.0), if you start the machine with no disks in the drives, hold down COMMAND and type S at the startup, the M20 will show a little spider crawling on the screen. Many thanks to Neil for the suggestion!

Page log

  • February 19, 2023 - Added the easter egg FAQ.
  • January 30, 2023 - Added the suggestion about the MDA Tulip monitor, thanks to Retro Nora
  • December 24, 2022 - Added the page log, correction of typos, added a few Q&A.
  • May, 5, 2007 - Added other questions.
  • December 30, 2005 - Page creation.

M20 lineart decoration


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