VU-Write

SyncMaster

Products: Vu-Write

Date: 1983

Type: Cassette

Platform(s): TS 1000

VU-Write is a document processor that allows users to create, edit, and print text documents such as letters. It supports configurable record lengths (up to 30 characters per line), two user-definable tab stops, a document title field, and a saved-program name field. The text editor provides insert, delete, and block-move operations on lines stored in a two-dimensional string array D$(L1,L2), where L1 (maximum line count) is calculated as INT(11144/L2) to fit within available memory. Output is sent to a printer via LPRINT, with lines beginning with “/” treated as blank lines and text right-padded to a fixed column offset of 30 minus the record length. The program uses RAND USR calls at lines 670 and 1010 to invoke machine code routines embedded in the REM statement at line 1.

Program Analysis

Program Structure

VU-Write is organized into clearly labeled subroutines and sections, each introduced by a REM comment. The main modules are:

Lines 100–390: Display subroutine — renders document lines on screen scrolling upward from the current line.
Lines 500–895: Text editor — handles line entry, move operations, and navigation.
Lines 900–990: Title editor — sets the document title stored in T$.
Lines 1000–1090: Main menu — presents four top-level options (File, Write, LPrint, Save).
Lines 1100–1179: File setup — configures record length, allocates D$() array.
Lines 1180–1199: Initialization subroutine — sets constants and dimensions ancillary arrays.
Lines 1200–1295: Tab/Title/Text sub-menu — secondary menu branching to tabs, title, or text editor.
Lines 1300–1395: LPrint — sends the document to the printer.
Lines 1400–1440: Save — saves the program (including data) to tape.
Lines 1450–1490: Init — cold-start entry point, calls the init subroutine then falls through to Save.

Machine Code Usage

Line 1 contains a REM statement that encodes machine code routines directly in the program listing. Two entry points are called explicitly:

RAND USR VAL "16514" (line 670) — called after a line is confirmed non-empty before advancing the line pointer, likely performing a screen or memory operation.
RAND USR VAL "16530" (line 1010) — called at the start of the main menu, likely initializing the display or clearing the screen in a specific way.

Using VAL "number" as the argument to USR is consistent with the program-wide idiom of passing numeric literals through VAL to save memory by avoiding storing floating-point number representations inline.

Key BASIC Idioms

The program makes extensive use of several space- and speed-saving idioms:

VAL "number" in GO TO/GO SUB: Almost every branch target is written as GOTO VAL "NNN" rather than a bare numeric literal, saving five bytes per number by storing the line number as a string rather than a five-byte floating-point value.
Named constants A and B: A is set to 0 and B to 1 in the init subroutine (lines 1180–1181). These are used throughout as zero and one, again avoiding the five-byte floating-point overhead for frequently used small integers.
C as a menu return address: C is set to 1000 (line 1182), and GOTO C is used as a universal “return to main menu” throughout every module.
P as a long pause value: P is set to 40000 (line 1183) and used in PAUSE P followed by INKEY$ polling — the standard efficient keypress-wait idiom.
S$ as a blank/padding string: S$ is dimensioned to 32 characters (line 1190) and used as a blank-line sentinel and screen-clearing padding throughout.

Document Storage and Memory Calculation

After the user specifies a record length Q (1–30 characters), the program calculates the maximum number of lines as INT(11144/L2) (line 1174), where 11144 is an empirically chosen constant representing available string space. The two-dimensional array D$(L1,L2) is then dimensioned at line 1176. The length of the largest line number in decimal is stored in L via LEN STR$ L1 (line 1175) and used for column alignment in the editor display.

Text Editor Logic

The editor at lines 500–895 operates around a current-line pointer L3 and a mode flag F:

F value	Mode
0	Normal navigation/entry
1	Display refresh only
2	Move — source line selected, awaiting destination
3	Move — performing the block copy

Entering “M” as the first character of a line number (line 620) sets move mode. The block-move routine (lines 800–895) copies a user-specified quantity of lines from source L4 to destination L3, adjusting iteration direction (Z1 is ±1) to avoid overwriting source data when the destination overlaps the source.

Lines beginning with “/” are treated as paragraph separators: the LPrint module (line 1364) outputs a blank line for them rather than their content, and they are skipped in the display module (line 200) when checking for blank lines.

Display Subroutine

The display subroutine (lines 100–390) renders lines bottom-up on the screen. Starting from line L3 and screen row Z2=16, it walks backward through D$(), printing each non-blank line. When L2<29 (short records), it also prints the line number at column 0 for reference. Any screen rows not filled by document content are cleared by printing S$ (the blank string) at those rows in the cleanup loop at lines 300–320.

Printer Output

The LPrint routine (lines 1300–1395) first prints a header consisting of the save name X$, a separator, and the title T$. Document lines are printed with TAB VAL "30"-L2, centering or indenting the text based on the chosen record length. Empty lines (D$(Z)=S$(TO L2)) are silently skipped (line 1362), while lines starting with “/” produce a blank printed line (line 1380).

Save Mechanism

The Save option (lines 1400–1440) uses SAVE X$ to save the entire program — including the populated D$() array — back to tape. The save name X$ can be updated at save time, defaulting to the previously stored name. This means a saved file reloads as a complete self-contained document.

Anomalies and Notes

Line 1130 checks INKEY$<>CHR$ VAL "118"; character 118 is the ENTER key token on this system — effectively waiting for ENTER to proceed past the caution screen.
Line 1262 is referenced in the tab-entry input validation (line 1272 GOTO VAL "1262") but the displayed listing shows the loop body starting at 1265; line 1262 does not appear explicitly, meaning the GOTO re-enters the FOR loop mid-body, re-prompting for the same tab without re-printing the label — a deliberate tight retry loop.
The initialization cold-start path (lines 1450–1490) calls the init subroutine, sets L1 and L2 to zero (skipping any caution prompt at line 1110), and falls directly into the Save option, prompting the user for a program name before any file is set up — likely intentional to establish the tape name early.

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Source Code
REM E£RND7 FAST )5 ;SGN ' ? ' GOSUB %KTAN 5~~ 67RND6~~RNDTAN 
REM DOCUMENT PROCESSOR
REM VU-WRITE / 2C.01 / 3069 
REM PROPRIETARY TO:
REM MANAGEMENT SERVICES CO. 
REM ** DISPLAY **
LET Z1=L3
LET Z2=VAL "16"
LET Z3=A
IF L2<VAL "29" THEN LET Z3=L+B
IF D$(Z1)=S$( TO L2) AND Z1<>L3 THEN GOTO 250
IF L2<29 THEN PRINT AT Z2,0;Z1;"    ";
PRINT AT Z2,Z3;D$(Z1);
LET Z2=Z2-1
IF Z2<0 OR F=1 THEN RETURN 
LET Z1=Z1-1
IF Z1 THEN GOTO 200
FOR Z=Z2 TO 0 STEP -1
PRINT AT Z,0;S$;
NEXT Z
RETURN 
REM ** TEXT **
CLS 
IF NOT L3 THEN GOTO VAL "600"
LET F=A
GOSUB VAL "100"
PRINT AT VAL "18",A;R$;"--LINE";S$( TO VAL "28");"ENTER LINE NO.: (1<=";L1;",M,E)"," ";R$( TO L);S$( TO VAL "31"-L)
LET F=A
INPUT Q$
IF Q$="" THEN GOTO VAL "650"
IF Q$(B)<>"M" THEN GOTO VAL "625"
LET F=VAL "2"
LET Q$=Q$(VAL "2" TO )
IF NOT LEN Q$ OR LEN Q$>L THEN GOTO VAL "610"
IF Q$(B)="E" THEN GOTO VAL "1220"
LET Q=A
FOR Z=B TO LEN Q$
IF Q$(Z)<"0" OR Q$(Z)>"9" THEN LET Q=B
NEXT Z
IF NOT Q THEN IF VAL Q$>=B AND VAL Q$<=L1 THEN GOTO VAL "640"
GOTO VAL "610"
LET L3=VAL Q$
GOTO VAL "680"
IF L3=L1 THEN GOTO VAL "610"
IF NOT F THEN LET F=B
IF L3 AND F<VAL "3" THEN IF D$(L3)<>S$( TO L2) THEN GOTO VAL "670"
GOTO VAL "675"
RAND USR VAL "16514"
LET L3=L3+B
IF F=VAL "3" THEN GOTO VAL "800"
GOSUB VAL "100"
PRINT AT VAL "19",VAL "5";L3
IF F<VAL "2" THEN GOTO VAL "700"
PRINT AT VAL "19",A;"MOVE"," TO ";
LET F=VAL "3"
LET L4=L3
GOTO VAL "610"
PRINT TAB VAL "10";":";S$( TO VAL "20"),TAB B;R$( TO L2);S$( TO VAL "30"-L2);AT VAL "21",T(B);"+";AT VAL "21",T(B+B);"+"
SLOW 
INPUT Q$
FAST 
IF Q$="" THEN GOTO VAL "600"
LET D$(L3)=Q$
LET F=B
GOSUB VAL "100"
GOTO VAL "600"
LET Z1=B
LET Z2=L1-L4+B
IF L3>L4 THEN LET Z2=L1-L3+B
PRINT L3,TAB VAL "6";"QTY TO MOVE: (0<=";Z2;")";S$;AT VAL "21",A;R$( TO L)
INPUT Q
IF Q<A OR Q>Z2 THEN GOTO VAL "840"
IF NOT Q THEN GOTO VAL "600"
LET Q=Q-B
IF L3<=L4 THEN GOTO VAL "870"
LET L3=L3+Q
LET L4=L4+Q
LET Q=-Q
LET Z1=-Z1
FOR Z=A TO Q STEP Z1
LET D$(L3+Z)=D$(L4+Z)
NEXT Z
IF L3<=L4 THEN LET L3=L3+Q
GOTO VAL "780"
REM ** TITLE **
CLS 
PRINT "OPTION: TITLE";AT VAL "11",A;"TITLE:  ";T$;AT VAL "21",B;R$( TO 24)
INPUT Q$
IF Q$="" THEN GOTO VAL "1220"
LET T$=Q$
GOTO VAL "1220"
REM ** MENU **
RAND USR VAL "16530"
FAST 
CLS 
PRINT TAB VAL "11";"""VU-WRITE""",TAB VAL "7";"DOCUMENT PROCESSOR",TAB B;R$,,TAB VAL "11";"1. FILE",,TAB VAL "11";"2. WRITE",,TAB VAL "11";"3. LPRINT ",,TAB VAL "11";"4. SAVE ",,,,TAB VAL "6";"ENTER OPTION: (1<=4)",,TAB B;R$,TAB VAL "10";"** STATUS **",,," SAVED: ";X$," TITLE: ";T$;" LINES: ";L1,"LENGTH: ";L2," TAB 1: ";T(B)," TAB 2: ";T(B+B)
PAUSE P
LET Q$=INKEY$
IF Q$<"1" OR Q$>"4" THEN GOTO VAL "1030"
CLS 
GOTO VAL Q$*VAL "100"+C
REM ** FILE **
IF NOT L1 THEN GOTO VAL "1140"
PRINT "OPTION: SET FILE";AT VAL "8",VAL "6";"%C%A%U%T%I%O%N:  THIS OPTION",,TAB VAL "3";"WILL CLEAR AND REDEFINE THE",,TAB VAL "5";"TEXT FILE.  PRESS %E%N%T%E%R",,TAB VAL "10";" TO CONTINUE."
PAUSE VAL "60"
IF INKEY$<>CHR$ VAL "118" THEN GOTO C
CLS 
PRINT "OPTION: SET FILE";AT VAL "11",VAL "11";"(1<=30)";AT VAL "10",VAL "4";"ENTER RECORD LENGTH: ";
INPUT Q
IF Q<B OR Q>VAL "30" THEN GOTO VAL "1150"
PRINT Q
POKE VAL "16507",Q
PRINT AT VAL "21",VAL "7";"CORRECT? (%END-Y-N)"
PAUSE P
IF INKEY$="Y" THEN GOTO VAL "1170"
IF INKEY$="N" THEN GOTO VAL "1140"
GOTO C
CLEAR 
GOSUB VAL "1180"
LET L3=A
LET L2=PEEK VAL "16507"
LET L1=INT (VAL "11144"/L2)
LET L=LEN STR$ L1
DIM D$(L1,L2)
GOTO C
LET A=VAL "0"
LET B=VAL "1"
LET C=VAL "1000"
LET P=VAL "40000"
LET R$="------------------------------"
DIM S$(VAL "32")
DIM T(VAL "2")
DIM T$(VAL "24")
DIM X$(VAL "8")
RETURN 
REM ** TAB **
IF NOT L1 THEN GOTO C
CLS 
PRINT TAB VAL "11";"""VU-WRITE""",TAB VAL "7";"DOCUMENT PROCESSOR",TAB B;R$,,TAB VAL "12";"1. TABS",,TAB VAL "12";"2. TITLE",,TAB VAL "12";"3. TEXT",,,,TAB VAL "6";"ENTER OPTION: (1<=3)",,TAB B;R$
PAUSE P
IF INKEY$="3" THEN GOTO VAL "500"
IF INKEY$="2" THEN GOTO VAL "900"
IF INKEY$<>"1" THEN GOTO C
CLS 
PRINT "OPTION: SET TABS";AT VAL "10",VAL "2";"ENTER TAB POSITIONS (0<=";L2;")",,TAB VAL "5";"TAB 1:"," TAB 2:"
FOR Z=B TO B+B
PRINT AT VAL "12",Z*VAL "12";"%<"
INPUT T(Z)
IF T(Z)<A OR T(Z)>L2 THEN GOTO VAL "1262"
PRINT AT VAL "12",Z*VAL "12";T(Z)
NEXT Z
PRINT AT VAL "21",VAL "9";"CORRECT? (Y-N)"
PAUSE P
IF INKEY$<>"N" THEN GOTO VAL "1220"
GOTO VAL "1250"
REM ** LPRINT **
IF NOT L1 THEN GOTO C
PRINT "OPTION: LPRINT ";AT VAL "11",VAL "7";"OK TO PRINT? (N-Y)"
PAUSE P
IF INKEY$<>"Y" THEN GOTO C
LPRINT X$,S$,T$,,,,,
FOR Z=B TO L1
IF D$(Z)=S$( TO L2) THEN GOTO VAL "1390"
IF D$(Z,B)="/" THEN GOTO VAL "1380"
LPRINT TAB VAL "30"-L2;D$(Z)
GOTO VAL "1390"
LPRINT 
NEXT Z
GOTO C
REM ** SAVE **
PRINT "OPTION: SAVE ";AT VAL "6",B;"ENTER PGM NAME: (";X$;",END)"
INPUT Q$
IF Q$="END" THEN GOTO C
IF Q$<>"" THEN LET X$=Q$
PRINT AT VAL "6",A;S$,TAB VAL "7";"PGM NAME: ";X$,,,,TAB VAL "5";"PRESS %E%N%T%E%R WHEN READY",,TAB VAL "8";" OR %END TO ABORT."
PAUSE P
IF INKEY$<>CHR$ VAL "118" THEN GOTO C
SAVE X$
GOTO C
REM ** INIT **
GOSUB VAL "1180"
LET L1=A
LET L2=A
GOTO VAL "1400"

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