The Model 16 was the same as a Model 12 with the 68000 add-on. It was launched a few time after the Tandy TRS 80 model IV. The Z80 processor was used for I/O. Up to four hard disks could be connected (8.4 mb each). It was compatible with the Tandy TRS 80 model II thanks to the Z80 and could run the Model II operating system.
This 68000 chip set and associated memory were much more than a speed improvement. It created a multi-user Unix-based system (actually Xenix, which was just a scaled down Unix). Interestingly, Xenix was developed in part by Microsoft, it was probably the basis upon which some Unix-like functionalities were added to MS-DOS 2.0, like sub-directories, pipes and re-direction.
The 16/6000 had a maximum memory capacity of 768K, and up to 9 serial ports for external terminals. These limits were partly just physical, due to limited card slot space. The 3-port serial cards had jumpers that would have allowed quite a few of them given an external card cage (never produced).
The 768K memory limit was later bumped to 1 MB when 64K memory chips became available. The original machine used a memory card of 256KB populated with 16K chips, and cables were available to support up to three cards. With 64K chips only one card was needed to give 1 MB of memory. Operating system limitations prevented using multiple 1 M cards to expand further in user memory space, but it was possible with software to utilize up to an additional 7 MB of memory as the system "swapper" which, given only 1 MB of user space, was almost always a source of performance loss if handled by the hard drive.
Thanks to Mark Brumlik for the main part of information.
Dav is correct, the original Model 16 had the single full height 8" floppy drive like the Model II, not the two slimline drives shown here. However, the drive on the model 16 had 1.25 MB capacity as opposed to the Model II''s 500k capacity.
I worked on one of these briefly in Model II mode using COBOL language software to write a VHS tape inventory program. But, alas, the owner of the store (also a Radio Shack store) decided he''d rather have the system put on a Model III instead so he could sell it to other video renting businesses in the area. I did get to play with the COBOL compiler quite a bit though.
Friday 26th December 2014
Chuck Rose (Vermont, USA)
I loved this machine! Never had one, though - still in college no money.
In 2004 someone posted a query on how to get out their data - the best way with incompatible machines is over RS232 - the only common interface among almost all machines.
Write a program to dump $ read hex (with checksum if so inclined) on both systems, start transferring.
Did this so many times in the 1980''s and 1990''s working with industrial applications..
Friday 27th September 2013
The picture displayed and the specs are for the TRS-80 Model 16b/Tandy 6000. The original Model 16 was a smaller cabinet based on the original Model II.