Clicking a RAM or ROM component with the Poke Tool brings keyboard and mouse focus to the component (indicated by a red rectangle), allowing for the contents to be viewed or edited. Because Poke Tool editing all takes place within a very small space, the interface for this is severely but necessarily constrained. For all but the simplest editing, it is more convenient to right-click the RAM and select "Edit Contents..." to bring up the integrated hex editor.
The Poke Tool has two modes of operation: You can edit the address displayed, and you can edit an individual value at some memory location.
Editing Addresses: Use the Poke Tool and click anywhere within the memory component but outside the gray box holding the memory contents. Logisim will draw a red rectangle around the address at the upper left corner. From here:
Typing R or r will clear the contents of memory.
Typing hex digits will change the address (assuming the new address isn't too large) and scroll the memory contents to show that address.
Scrolling with the mouse wheel increments or decrements the address and scrolls the memory forward or backward.
The Down (or Enter) key will increment the address and scroll the memory contents forward by one row.
The Up (or Backspace or Delete) keys will also increment or decrement the address to key will decrement the address and scroll the memory contents backwards by one row.
The Page Down (or Space) and Page Up keys will increment or decrement the address to scroll the memory contents forward or backward by one full page.
Editing Contents: Use the Poke Tool and click anywhere within the memory component within the gray box holding the memory contents. Logisim will draw a red rectangle around the memory cell currently being edited. From here:
Typing R or r will clear the contents of memory.
Typing hex digits will change the contents of that cell.
Scrolling with the mouse wheel moves up or down to an adjacent memory cell.
The Up, Down, Left, and Right arrow keys move to an adjacent memory cell.
The Page Up and Page Down keys move up or down by a full page.
The Backspace (or Delete) and Tab (or Space) keys similarly move to the previous or next memory cell.
Next: Memory Import/Export Format.