The OLIGER 2068 FLOPPY DISC INTERFACE is manufactured by the JOHN OLIGER COMPANY, 11601 Whidbey Dr., Cumberland, IN 46229. The cost: Assembled/Tested version- $177.90, and kit version- aprox. $144.90 (prices include postage). The Disc Operating System (DOS) is called JLO SAFE (Simple And Fast Extended) Disc BASIC.
This disc drive system interface will support 3″, 3½” and 5¼” floppy disc drives for the T/S 2068 computer. The drives may either be single or double-density IBM type. The system is readily altered in BASIC to accommodate head step rates from >0 to 30 ms and number of tracks per side from 10 to 250. The interface will operate one to four drives, and is powered by the computer.
The hardware consists of a mother board (3 3/4 x 4 3/8), that plugs into the rear computer port. It includes 4 circuit board slots, and a “feed-thru” port that duplicates the computer’s rear port. Two boards (“A” and “B”) plug into any of the 4 slots. Board “A” (3 1/4 x 3 1/2) provides the disc drive cable connector. This board also contains the IC gates (mainly for the address lines), output buffers to the disc drive, an 8 MHz clock, and the WD 1770 FD Controller/ Formatter IC. This chip is a special device making the system’s design possible. This board also includes RGB circuitry.
Board “B” (3 1/4 sq.) carries an EPROM (the operating program), gates and buffers, and a 6264 SCRAM (an 8K of buffer memory, static RAM) IC. Where essential, the circuit boards have gold-plated edge traces and socket fingers. The mother board has 4 feet to level it. (Note: This evaluation of the Oliger Interface was accomplished with the following equipment- T/S 2068, A&J Micro Drive and printer I/F, T/S 2040 printer, an Olivetti PR-2300 printer, a TV, and an AMDEK Model Three 3″ Disc Drive unit).
Documentation is provided for assembly of the kits, testing the assembled boards, disc drive operation, and checks for proper switching of drive 0 and 1. A simple but effective program is furnished for a menu that loads the desired program from disc by number selection.
The JLO SAFE disc BASIC commands are adequate to operate the system, but future up-dates (and the proposed KINGSLEY DOS) will provide additional simple commands. Besides the formatting commands, there are commands for SAVE, LOAD, and printer select which requires a printer interface, or 2040 (Note: John Oliger has available an optional printer I/F board, that is compatible with the Aerco interface).
There are two SAVE commands. SAVE /0 works only on about the first 1 1/2K of disk memory on each side. This is reserved for menu program storage. SAVE /n saves the entire state of the machine to disc. “n” is any number of 1 or greater, depending on the drives. For 40 tracks single-sided, the limit is 40/10 = 4. The “/” is common to all commands. No extra space or character can be in front of it.
Several other useful features include include the status of operations, which is useful for trouble-shooting…and formatting can be accomplished without losing a program in the computer’s memory (a big advantage to not using the computer’s RAM for disc operations).
The only problem experienced, was of my own making. In going thru the steps in formatting, I was aware that I was using an 80-track drive, so I used this figure for the number of tracks. Several loading errors made me review things, and in the instructions on commands, I found that this figure was “per side”. If I had read this section before starting, this problem would not have surfaced.
I do have a suggestion for improved documentation: that the reader be directed to review the command section before starting the section on Testing and Using. Also, some of the information in the price sheet data would be good to have in the manual.
A disadvantage (which may be common in other disc systems) is that only 4 files per side can be saved with 40 tracks. Double-density gives a maximum of 92K bytes per side, so there can be a single file to about this length.
I tried some operations common to my usual computer use. TASWORD TWO was easily converted from Micro Drive commands to this system. I also tried a Zebra OS64 Cartridge, with no conflict. Because this system stores in blocks, speed of SAVE and LOAD is near the limit of the drives, about 50K. PRO/FILE LOADS in 4 seconds, and this program is near memory capacity!
For those interested in this interface, I recommend a letter to John Oliger for details and prices. Also ask about a new development: data transfer between disks, COPY, and SAVE with just a press of a button!