Peace

This program generates “peace dove” graphic stickers using UDGs (User Defined Graphics) and the TS2068’s LPRINT facility for a thermal or RS-232 printer. It defines 14 UDGs (characters a through n) by POKEing 8-byte bitmap data into memory via USR “a”, constructing a multi-character dove-and-bomb illustration assembled from those custom characters. Three output modes are offered: a stand-alone peace sticker (LPRINT), a combined address label plus graphic (LPRINT), and an on-screen display using PRINT AT. Block graphics characters (▖▌▀, etc.) are used for the sticker’s decorative border. The program includes a subroutine (lines 530–640) that displays explanatory text across multiple screenfuls, using a PAUSE 0 keypress gate between pages.

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Program Analysis

Program Structure

The program is organized into a main flow with several distinct sections connected by GO TO and GO SUB:

1. Initialization (lines 10–80): Loads UDGs via subroutine at line 660, then runs the introduction text subroutine at line 530.
2. Menu (lines 90–160): Presents three options — sticker ("s"), address label ("a"), or display-only ("d") — and branches accordingly.
3. Sticker output (lines 170–260): LPRINTs a bordered peace-dove graphic with slogans.
4. Address label output (lines 270–390): LPRINTs a combined address and peace-dove graphic.
5. Screen display (lines 400–520): PRINTs the dove graphic to the screen using PRINT AT, then waits for "s" or "m" input.
6. Introduction subroutine (lines 530–650): Displays explanatory text across multiple screens, calling the keypress-wait sub at line 620.
7. UDG loader (lines 660–810): Reads 112 bytes of bitmap data and POKEs them into UDG memory.
8. Save line (820): SAVE "PEACE" LINE 30 saves with auto-run from line 30.

UDG Definition and Layout

Line 660 uses a FOR loop reading 112 bytes (14 UDGs × 8 bytes each) from DATA statements at lines 670–800, POKEing them sequentially starting at USR "a". This defines characters a through n, which together form the peace-dove-and-bomb composite image. The dove graphic is assembled across a 4×2 block of UDGs (rows printed at lines 400–450 and within the LPRINT blocks):

UDG	Role in image
a	Dove body top-left
b	Dove body top-right / wing
c	Dove mid-left
d	Dove mid-right / bomb intersection
f, g, h	Lower dove / tail sections
i, j, k	Bomb lower sections
l, m	Wing or bomb mid sections
n	Bomb/fuse detail

The :: block graphic (full block █) appears inline within the LPRINT strings alongside UDGs to fill out the bomb shape, demonstrating mixed use of UDGs and built-in block graphics characters in a single image.

DATA Anomaly: Variable y in DATA Statements

Lines 670–800 contain DATA entries using the bare token y (e.g., DATA 0,y,y,56,60,62,63,y). In Sinclair BASIC, READ will evaluate each data item as an expression, so y refers to the numeric variable y. Since y is never explicitly assigned in the program, it defaults to 0. This means every occurrence of y in the DATA statements is effectively 0, making it a shorthand zero-fill technique — intentional or otherwise. The programmer likely used y as a readable stand-in for zero to indicate “empty row” bytes in the UDG bitmaps.

Sticker Border Technique

Both LPRINT sticker formats use Spectrum/TS2068 block graphics for their borders. The top border (e.g., line 170) uses .... repeating ▄ characters, while the bottom border (line 240) uses '''''' repeating ▀ characters. The left and right sides use : (▌) to create a solid rectangular frame. This is a common technique for drawing pseudo-box borders entirely within character cells without any additional drawing routines.

Multi-Screen Text Subroutine

The introduction subroutine starting at line 530 spans several PRINT statements with embedded newlines created by the ' idiom (which generates a PRINT newline in Sinclair BASIC). At line 560, it calls the keypress-wait subroutine at line 620 via GO SUB 620, which uses PAUSE 0 at line 630 to halt until any key is pressed. This is a standard Sinclair idiom for paged text display. The subroutine at line 620 doubles as a reusable “any key” prompt since it is also called from line 620 directly by falling through from line 610.

Notable BASIC Idioms

• The PRINT OVER 1; AT 0,10;"_____________" at line 40 and 570 underlines the title by printing underscores in OVER 1 mode, which XORs them with the existing text pixels to create an underline effect without erasing characters.
• The menu loop (lines 100–160) uses sequential IF … THEN GO TO tests rather than a computed branch, a common pattern in BASIC of this era.
• After each LPRINT section (lines 250, 380), the program jumps back to the CLS/menu at line 90 rather than falling through to a STOP, which appears immediately after as a safety catch (lines 260, 390) in case of unexpected flow.
• The SAVE "PEACE" LINE 30 at line 820 causes the program to auto-start at line 30 (skipping the REMs) when loaded.

Bugs and Anomalies

• The REM at line 70 contains a coded reference to the graphic layout: n,6;ba;n,6;c::dn;…. This appears to be a developer note describing the UDG arrangement, left in the final program.
• Line 530 contains a typographical split in the word “the/service” — "I was in theservice" — suggesting the programmer miscounted the 32-character line width when formatting the text to fit the screen.
• The subroutine at line 620 is structured so that both line 560 (GO SUB 620) and line 600 fall through to it — line 610 calls it as a regular PRINT statement, then line 620 follows immediately. This means the “Any key for program” prompt and PAUSE are executed at both the mid-introduction pause and the end, which is the intended paged behavior.