Timex Application Development Library ASC No. 004, version 002, by C. Corcoran, February 22, 1984. It’s a machine-code module that gives BASIC programs the TS2068’s second display file at 24576. Programs can write text to either screen, clear and scroll ranges of lines, and read back characters and colors. They can also copy or swap lines between the two screens and choose which screen is showing.
These tapes were rebuilt from a transcription of Timex’s assembler listing, not from an original tape. Every instruction in the listing was checked against its printed bytes, and the code on these tapes comes from those bytes.
The download has three tapes and a README:
dualscreen.tap: the original module.dualscreen-patched.tap: the module with four bugs fixed. It loads and works the same way.dualscreen-demo.tap: a short demo that draws a help page on screen 2 while screen 1 is showing. It loads the original module after itself.
Load either module with CLEAR 57343: LOAD "dualscreen" CODE 57344. The README lists the calls. “Using Timex’s Dual Screen Mode Support” covers them in detail, along with the bugs and what the patched version changes.
Both versions were tested in an emulation of the TS2068 with the stock ROMs.
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Note: Type-in program listings on this website use ZMAKEBAS notation for graphics characters.