The Tandy M200

The successor of the M100 featured a bigger screen, more memory and alas more power consumption.

Semi-side Tandy M200 semi side Apart from the normal M100 applications (BASIC, TEXT, TELCOM, ADDRS) the 200 also features MSPLAN, Microsoft Multiplan 1.0. The Quick Reference guide is now on line.
Front Tandy 200 front Another M200 mystery is the small switch at the left which lets you choose between "DIR" and "ACP". This is about the modem used. "ACP" is acoustic coupler, "DIR" is direct (the modern way).
Inside M200 board The m200 with top and keyboard removed. The lower board contains all the RAMs and the option ROM.
PDD2 Portable Disk Drive 2 The Portable Disk Drive was connected through the serial port and needed a small driver program. The floppies are standard 3 1/2 ", but the format quite special. Tandy didn't develop the drives themselves, but used existing Brother devices. Brother used them as storage for programmable sewing machines. More info on the Portable Disk Drive page.

RAM fault Bad solder connection My M200 had a problem with one of the memory banks. If the bank was empty, it still had only about 3000 bytes free, while 19590 Bytes free is standard. Assuming a case of bitrot, I expected having to replace one of the RAM's on the module. While creating the schematic of the module I noticed a suspect connection (Right-most SMD-pin). Resoldering it restored the 19590 Bytes. An original Tandy production fault!

Disclaimer: I have no documentation of this machine. So don't mail me for info (unless you want to part from yours :-) ).

Thanks to James Korman, the M100 Multiplan Quick Reference guide is now online. For now only in jpg format, but I'll try to convert it into a nice multipage PDF document in time. Note this is not just copyrighted material, but even ©1984 Microsoft Copyrighted Material. So if anyone has a problem with it being online, please let me know.

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Last update: 2014-06-09