Using the LKDOS cartridge with your Oliger disk system will give you extra commands and let you be compatible with all other TS2068s running LKDOS.
Insert the LKDOS cartridge into the cartridge port and turn on the TS2068. Some TS2068s will not initialize when the LKDOS and SAFE boards are used together. If the TS2068 seems to lock up on power up, you will need to modify either the LKDOS or the SAFE board as described below.
The reason for the problem is that both boards are trying to initialize at once. Both boards have a reset circuit that makes them became active at power up.
If you have a power up problem when the LKDOS is installed, you can add a disable switch to the LKDOS cartridge.
To add a disable switch, connect a small wire to the unused hole in the PC board near pin 1 on the 74LS74. This hole is between the notched end of the 74LS74 and the 470 ohm resistor next to it. Carefully scrape the green solder mask off the pad and solder the wire to it. You can add a miniature switch to ground this wire to disable the LKDOS. The ground trace runs around the edge of the solder side of the cartridge.
If you turn on the TS2068 with the switch disabled, you will have to initialize to the cartridge with the command RANDomize USR 96 after power up.
By the way, you don’t need to use RAND USR 100: OPEN #4, “dd” when running LKDOS, just put RAND USR 100: in front of all commands.
An alternate method of fixing the initialization problem is to disable the power-on reset circuitry on the SAFE board. This way is really better because the LKDOS cartridge has special software to initialize the SAFE board after it has initialized itself on power up.
The easiest way to do this is to remove the 74HCT74 on the SAFE board from its socket and bend pin 1 out. Put the IC back into its socket and wire pin 1 to +5V. Pin 14 on the same IC has +5V on it so you can just connect these two together with some fine wire. If you don’t want to solder it, just use a few turns of wire on each pin.
Now, if you turn on the TS2068 while pressing “i”, the LKDOS will initialize the SAFE board after it has initialized itself. If you load an AUTOSTART program with LKDOS though, it will not initialize SAFE. Use the RESTORE command in SAFE to initialize SAFE.
When using the snapshot button, only have the DOS that you want enabled to respond to the NMI as the LKDOS can also perform NMI saves.
If you are using the LKDOS with the SAFE board enabled, you shouldn’t use LKDOS commands that use PRINT #4: such as windows, printer driver, sequential-files or other commands preceded by PRINT #4 (use RAND USR 100: to precede commands). This is because the vectors for these commands share the same memory patch area as the JLO NMI vector and they will cause the JLO NMI to conflict. When using these LKDOS commands, disable the SAFE board.