Text Printer

Text Printer is a menu-driven utility that reads machine-code text data stored at memory address 35000 and sends it to either a full-size parallel/serial printer or a Timex/Sinclair 2040 thermal printer. For the full-size printer path, it reads 18 lines of 64-character-wide text per page, printing a header with a page counter. The TS2040 path transposes the text sideways by iterating columns and rows in reverse order, effectively rotating the output 90 degrees to achieve 64-column printing on the narrow thermal roll. A machine-code print driver is expected to reside at address 34000, and a separate machine-code block (785 bytes from address 33000) is saved and loaded alongside the BASIC program. The utility was designed specifically for text data from BYTE POWER Magazine issues (August 1986 through December/January 1987) stored as binary CODE files.

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Program Structure

The program is divided into four logical sections accessed via a central menu:

1. Lines 80–110: Full-size printer output routine — reads 18 lines × 64 characters per page from address 35000 upward, printing page headers.
2. Lines 1005–1080: TS2040 thermal printer routine — transposes text sideways, 64 columns wide, using nested loops that invert row/column order.
3. Lines 2000–2060: Main menu — uses PEEK 23560 to read the last key pressed after PAUSE 0, dispatching on ASCII codes 49–53.
4. Lines 3000–3070: Paginated instructions screen, split across two PAUSE 0-gated screens.

Lines 9000 and 9999 form a save/load bootstrap: SAVE "TEXT PRINT" LINE 9000 automates reloading, and SAVE "CODES" CODE 33000,785 preserves the machine-code block.

Machine Code Usage

Two machine-code blocks are involved:

• A print driver expected at address 34000, loaded separately before running the program (not loaded by this BASIC).
• A 785-byte block at address 33000, saved as "CODES" in line 9999 and called via RANDOMIZE USR 33768 in line 2050 — presumably a tape loader or LOAD helper routine invoked before LOAD n$ CODE 35000.

Printer Routines

The full-size printer path (lines 80–110) is straightforward: it steps char through memory in 64-byte strides, assembling each line into a$ with a FOR x=char TO char+63 loop, then LPRINTs it with an 8-space indent. Each page consists of 18 such lines, with a dashed separator and page number printed at the top.

The TS2040 path (lines 1005–1080) performs a 90-degree rotation. The outer loop iterates over 64 column positions (c=0 TO 63) and the inner loop walks 18 rows in reverse (l=17 TO 0 STEP -1), reading PEEK (char+c+l*64). This re-orders a 64×18 block into 64 rows of 18 characters, printing each rotated column as one printer line — effectively printing the text sideways to exploit the 2040’s narrow roll width.

System Variable Manipulation

Lines 1020–1030 and 2010 directly manipulate the system variable pair at addresses 23606–23607, which controls the printer buffer pointer (PRBUFF / PR_CC). Setting both to specific values resets or repositions the printer state. The value a=32744 (line 1010) and the reset pair 0,60 (hex 003C = address 60) are used to point to a custom print buffer or restore the default.

Key BASIC Idioms

• PAUSE 0 followed by PEEK 23560 reads the ASCII value of the last key pressed from the LAST_K system variable — a common polling idiom avoiding INKEY$ string comparison.
• IF PEEK char=0 THEN LET char=char+1 (line 80) skips a leading null byte, guarding against off-by-one alignment in the CODE file.
• IF b$="FREE " OR b$="STICK" in line 1060 uses the TS2068-specific keyword tokens ~ (FREE) and | (STICK) — these are single-byte tokens that may appear in raw memory and are filtered out, replaced with a space to avoid corrupting printer output.
• The DIM p$(64) at line 1010 creates a 64-character string for the page header, accessed character-by-character as p$(c+1) inside the column loop.