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Examining memory or I/O content

The Address and Data displays are always in sync, that is, the Data Display shows the content of the memory location or I/O register which address is currently shown by the Address Display. If it is a memory address, the I/O Lamp will be off. If it is an I/O address, the I/O Lamp will illuminate and only the first eight bits of the Address Display will be valid (since I/O addresses are 8-bits).

Pressing the EXAM- or EXAM+ button causes the Console to read the previous or next address respectively. The new address will be shown in the Address Display and the content for that location will be shown in the Data Display. Whether this is memory or I/O address depends upon the I/O switch status: if it is in active position (up) the address corresponds to I/O; it will be a memory location otherwise.

For examining an arbitrary memory location or I/O, proceed as following: Use the entry switches for entering the desired address then press the LD button. Again, if the I/O switch is in its active position (up) the address entered will be interpreted and an I/O address and only the first eight bits will be valid. Once the LD button has been pressed, the corresponding memory location or I/O will be read so the Data Display will show the content and the Address Display will show the address.

Keying in the Entry Switches will not cause any effect until either the LD or DEP button is pressed. You can, for example, enter a new address as described above then use the EXAM-, EXAM+ buttons to examine consecutive locations and, later on, press the LD button for returning to the initial address, which is still given by the Entry Switches.

LC-81 Homebrew Minicomputer -- this software is based on Help Books running at melissa