--- title: "Weather Analysis" id: 57442 type: "computer_media" slug: "weather-analysis" url: "http://localhost/computer_media/weather-analysis/" markdown_url: "http://localhost/computer_media/weather-analysis.md" published_at: "2024-10-05T13:47:45+00:00" modified_at: "2026-04-03T07:58:29+00:00" author: "David Anderson" featured_image: url: "http://localhost/wp-content/uploads/2024/10/243_WA.png" excerpt: "A rule-based weather station logger and forecaster that packs barometric pressure, wind, temperature, and precipitation into fixed-width string array records — then predicts tomorrow's weather." category: - name: "Archived Media" slug: "archived-media" taxonomy: "category" url: "http://localhost/category/archived-media/" post_tag: - name: "Downloadable" slug: "downloadable" taxonomy: "post_tag" url: "http://localhost/tag/downloadable/" - name: "TS 1000" slug: "ts1000" taxonomy: "post_tag" url: "http://localhost/tag/ts1000/" model: - name: "Timex/Sinclair 1000" slug: "ts-1000" taxonomy: "model" url: "http://localhost/model/ts-1000/" genre: - name: "Weather" slug: "weather" taxonomy: "genre" url: "http://localhost/type/weather/" media_contents: - id: 56736 title: "Timex Sinclair Public Domain Library Tape 1005" type: "computer_media" url: "http://localhost/computer_media/timex-sinclair-public-domain-library-tape-1005/" media_type: "Program" mediadate: "198x" images: - url: "http://localhost/wp-content/uploads/2024/10/243_WA.png" media_type_tags: "Weather" --- # Weather Analysis This program is a weather analysis and logging application that stores meteorological observations in a 90-row by 31-column string array A$(). Each record packs date, high and low temperatures (with sign), barometric pressure, weather condition code, precipitation, snowfall, and wind direction/speed into fixed-width fields within a single array row. The forecast module uses a rule-based decision table matching barometric pressure thresholds, pressure trend (steady/rising/falling), and wind direction to produce plain-language weather predictions. Normal climate data embedded in the listing is attributed to the National Weather Service at Harrisburg, PA (elevation 338 ft), suggesting a specific mid-Atlantic US location. The program uses FAST/SLOW mode switching during the date-search loop at line 3018 to speed up string comparisons across up to 190 records. *** ## Program Analysis ### Program Structure The program is organised as a menu-driven application with a splash/intro subroutine called at startup, then a main menu loop. Control flow is entirely via `GOTO` and `GOSUB`; there is only one subroutine (lines 2000–2090). The main functional sections are: 1. **Initialisation & intro** (lines 13–59): variable/array declarations, splash screen subroutine call. 2. **Main menu** (lines 60–130): displays options and dispatches on a single character input. 3. **Data entry / UPDATE** (lines 135–375): guided field-by-field entry of a daily weather record. 4. **Forecast** (lines 380–687): barometric pressure + trend + wind direction rule table. 5. **Display data** (lines 700–750): scrolls all stored records. 6. **Display normals** (lines 900–1040): hardcoded monthly climate normals. 7. **Search by date** (lines 3000–4020): linear scan of array for a matching date. 8. **Corrections** (lines 5000–6010): locate a record by date and re-enter all fields. 9. **Save** (line 9000): saves the program (and thus the in-memory array data). ### Data Storage Format All weather records are stored in a single two-dimensional string array `A$(90,31)`, giving a maximum of 90 records each 31 characters wide. The record counter `L` tracks how many records have been entered; the hard limit is 190 (checked at line 143), though the array only has 90 rows — this is a latent off-by-one capacity bug. | Columns | Field | Format | | --- | --- | --- | | 1–2 | Month | 2 digits | | 3–4 | Day | 2 digits | | 5–6 | Year | 2 digits | | 7–10 | High temperature | sign + 3 digits (e.g. `+076`) | | 11–14 | Low temperature | sign + 3 digits (e.g. `-006`) | | 15–19 | Barometric pressure | 5 chars (inches) | | 20 | Weather condition code | 1 digit (1–7) | | 21–25 | Precipitation | 5 chars (inches, e.g. `02.75`) | | 26–27 | Snowfall | 2 digits | | 28–31 | Wind direction + speed | 2-digit direction code + 2-digit speed | ### Forecast Rule Table The forecast section (lines 435–505) implements a classic barometric weather forecasting method using a cascade of `IF` conditions. Each rule tests three variables: `A` (barometer reading in inches), `B` (pressure trend 1–5), and `C` (wind direction 1–8). Sixteen rules cover combinations of high/low pressure, rising/falling trends, and wind quadrant, mapping to eleven distinct forecast messages. Each message block ends with `PAUSE 40000` (maximum pause, effectively waiting for a keypress) then `GOTO 60` to return to the main menu. Notably, no `ELSE` or default forecast exists: if none of the 16 conditions match the inputs, the program falls through lines 435–505 silently and drops into the first forecast print block at line 600, printing “FAIR, LITTLE IN TEMP” regardless. This is a logic gap rather than intentional design. ### FAST/SLOW Mode Usage The date-search loop at lines 3018–3055 and 5015–5040 calls `FAST` before iterating over up to `L` records comparing 4-character string slices. `SLOW` is restored either when the record is found or after the loop exhausts without a match. This is a practical optimisation for string-intensive searching, since display is not needed during the scan. ### Array Slicing as Structured Records The program makes extensive use of substring slicing on both the input buffer arrays (e.g. `B$(1,1 TO 8)`) and the main data array. Single-row auxiliary arrays (`B$` through `K$`) act as typed input buffers with fixed widths — a workaround for the lack of structured records. Input is always captured into these fixed-dimension arrays rather than plain string variables, which enforces field-width discipline. ### Notable Techniques and Idioms - Inverse-video text (e.g. `%W%E%A%T%H%E%R%`) is used for headers and highlighted prompts throughout. - `PAUSE 40000` is used as a “press any key” wait (maximum pause duration) rather than an `INKEY$` loop. - The display-all-records section (lines 705–730) calls `SCROLL` before and after each `PRINT A$(T)`, producing a double-scroll effect that may be an unintended display artifact. - Line 9000 saves the program with a filename containing an inverse character, functioning as an auto-run save. - After a correction is made (line 6010), control jumps to line 300 (the data-review/confirmation block) with `X=N`, reusing the update confirmation display — a tidy code-reuse pattern. ### Bugs and Anomalies - **Array capacity vs. limit mismatch**: `A$(90,31)` holds 90 rows, but the full check at line 143 triggers at `L=190`. Entering more than 90 records will cause an array subscript error before the guard fires. - **Forecast fall-through**: No default branch exists after the rule table; unmatched inputs silently fall into line 600. - **Condition code overlap**: Lines 485 and 475 both test `B=4` with overlapping `C` ranges (`C=3 OR C=2` vs. `C>=2 AND C<=4`), meaning line 475 will always match before line 485 for `C=2` or `C=3`. Line 485 is unreachable for those wind codes. - **Corrections omit snowfall until line 6000**: In the corrections module, the snowfall field input (`A$(N,26 TO 27)`) is at line 6000, separated from the logically adjacent wind entry at line 5190 by a jump to line 300 at line 6010 — the structure is correct but the wide line-number gap is potentially confusing. - **Misspellings in prose**: “MONTHES” (line 2057) and “MANTAINED” (line 2058) are present in the intro text. ## Source Code ``` 13 LET X=0 14 LET A=0 15 LET B=0 16 LET C=0 17 LET L=0 18 DIM A$(90,31) 19 DIM B$(1,8) 20 DIM C$(1,4) 25 DIM D$(1,4) 30 DIM E$(1,5) 35 DIM F$(1,1) 40 DIM G$(1,5) 45 DIM H$(1,3) 50 DIM I$(1,4) 55 DIM J$(1,31) 56 DIM K$(1) 59 GOSUB 2000 60 CLS 65 PRINT AT 0,5;"%W%E%A%T%H%E%R% %A%N%A%L%Y%S%I%S" 70 PRINT 75 PRINT AT 5,3;"UPDATE DATA ENTER %U" 80 PRINT AT 7,3;"FORECAST FROM DATA ENTER %F" 85 PRINT AT 9,3;"DISPLAY DATA ENTER %D" 90 PRINT AT 11,3;"DISPLAY NORMALS ENTER %N" 92 PRINT AT 13,3;"TO STOP ENTER %S" 93 PRINT AT 15,3;"SEARCH DATE ENTER %C" 94 PRINT AT 17,3;"CORRECTIONS ENTER %M" 95 PRINT AT 20,0;"%F%U%N%C%T%I%O%N???" 100 INPUT Y$ 105 IF Y$="U" THEN GOTO 135 110 IF Y$="F" THEN GOTO 380 115 IF Y$="D" THEN GOTO 700 120 IF Y$="N" THEN GOTO 900 122 IF Y$="C" THEN GOTO 3000 123 IF Y$="M" THEN GOTO 5000 125 IF Y$="S" THEN STOP 130 GOTO 95 135 CLS 140 PRINT " DATA UPDATE" 143 IF L=190 THEN PRINT "FILE FULL" 144 IF L=190 THEN PAUSE 40000 145 IF L=190 THEN GOTO 60 146 PRINT 150 PRINT "ENTER DATE (AS 12-30-83):" 155 INPUT B$(1,1 TO 8) 158 LET L=L+1 160 FOR X=L TO 190 165 LET A$(X,1 TO 2)=B$(1,1 TO 2) 170 LET A$(X,3 TO 4)=B$(1,4 TO 5) 172 LET A$(X,5 TO 6)=B$(1,7 TO 8) 175 PRINT "ENTER HIGH TEMPERATURE (AS +076)" 180 INPUT C$(1,1 TO 4) 185 LET A$(X,7 TO 10)=C$(1,1 TO 4) 190 PRINT "ENTER LOW TEMPERATURE (AS -006)" 195 INPUT D$(1,1 TO 4) 200 LET A$(X,11 TO 14)=D$(1,1 TO 4) 205 PRINT "ENTER BAROMETER (IN INCHES)" 210 INPUT E$(1,1 TO 5) 215 LET A$(X,15 TO 19)=E$(1,1 TO 5) 220 PRINT "ENTER GENERAL WEATHER CONDITION",,"1=FAIR",,"2=CLOUDY",,"3=RAIN" 223 PRINT ,"4=SNOW",,"5=THUNDERSHOWERS","6=SNOW FLURRIES",,"7=HEAVY RAIN" 225 INPUT F$(1,1) 230 LET A$(X,20)=F$(1,1) 235 PRINT "ENTER PRECIPITATION (INCHES)" 240 PRINT "AS:02.75" 245 INPUT G$(1,1 TO 5) 248 LET A$(X,21 TO 25)=G$(1,1 TO 5) 250 PRINT "SNOWFALL AMOUNT (AS 07)" 255 INPUT H$(1,1 TO 2) 258 LET A$(X,26 TO 27)=H$(1,1 TO 2) 260 CLS 265 PRINT "ENTER WIND DIRECTION AND SPEED:" 270 PRINT "USE THIS CODE:","01=N",,"02=NE",,"03=E",,"04=SE",,"05=S",,"06=SW" 273 PRINT ,"07=W",,"08=NW" 275 PRINT 280 PRINT "ENTER DIRECTION AND SPEED","AS FOUR DIGIT NUMBER ""0312""" 285 INPUT I$(1,1 TO 4) 290 LET A$(X,28 TO 31)=I$(1,1 TO 4) 295 CLS 300 PRINT "DATE: ";A$(X,1 TO 6) 305 PRINT "HI TEMP: ";A$(X,7 TO 10) 310 PRINT "LO TEMP: ";A$(X,11 TO 14) 315 PRINT "BAROMETER: ";A$(X,15 TO 19) 320 PRINT "CONDITIONS: ";A$(X,20) 330 PRINT "PRECIPITATION: ";A$(X,21 TO 25) 335 PRINT "SNOWFALL: ";A$(X,26 TO 27) 340 PRINT "WINDS: ";A$(X,28 TO 31) 342 PRINT "USE THIS CODE:","01=N",,"02=NE",,"03=E",,"04=SE",,"05=S",,"06=SW" 343 PRINT ,"07=W",,"08=NW" 345 PRINT 350 PRINT "%I%S% %T%H%I%S% %C%O%R%R%E%C%T% %?" 355 INPUT Z$ 360 IF Z$="N" THEN GOTO 135 365 LET L=X 370 IF Z$="Y" THEN CLS 375 IF Z$="Y" THEN GOTO 65 380 CLS 385 PRINT " FORECAST" 390 PRINT "ENTER BAROMETRIC PRESSURE:" 395 INPUT A 400 PRINT 405 PRINT "IS BAROMETER: ","1. STEADY",,"2. SLOW RISE",,"3. RAPID RISE" 406 PRINT ,"4. SLOW FALL",,"5. RAPID FALL" 407 PRINT "RAPID CHANGE IS ANY CHANGE ","IN EXCESS OF 0.06 PER HOUR." 410 INPUT B 415 PRINT 420 PRINT "WIND FROM:" 425 PRINT ,"1=N",,"2=NE",,"3=E",,"4=SE",,"5=S",,"6=SW",,"7=W",,"8=NW" 430 INPUT C 433 CLS 435 IF A>=30.2 AND B=4 AND C>=6 AND C<=8 THEN GOTO 625 440 IF A>=30.2 AND B=1 AND C>=6 AND C<=8 THEN GOTO 620 445 IF A>=30.1 AND B=1 AND C>=6 AND C<=8 THEN GOTO 600 450 IF A>=30.1 AND B=3 AND C>=6 AND C<=8 THEN GOTO 605 455 IF A>=30.1 AND B=4 AND C>=6 AND C<=8 THEN GOTO 610 460 IF A>=30.1 AND B=5 AND C>=6 AND C<=8 THEN GOTO 615 465 IF A>=30.1 AND B=4 AND (C=4 OR C=5) THEN GOTO 630 470 IF A>=30.1 AND B=5 AND (C=4 OR C=5) THEN GOTO 635 475 IF A>=30.1 AND B=4 AND C>=2 AND C<=4 THEN GOTO 640 480 IF A>=30.1 AND B=5 AND C>=2 AND C<=4 THEN GOTO 645 485 IF A>=30.1 AND B=4 AND (C=3 OR C=2) THEN GOTO 650 490 IF A>=30.1 AND B=5 AND (C=3 OR C=2) THEN GOTO 655 492 IF A<=29.8 AND B=5 AND C>=1 AND C<=3 THEN GOTO 680 493 IF A<=29.8 AND B=5 AND C>=3 AND C<=5 THEN GOTO 675 494 IF A<=29.8 AND B=3 THEN GOTO 685 495 IF A<=30.1 AND B=4 AND C<=4 AND C>=2 THEN GOTO 660 500 IF A<=30.1 AND B=5 AND C<=4 AND C>=2 THEN GOTO 665 505 IF A<=30.1 AND B=2 AND (C=5 OR C=6) THEN GOTO 670 600 PRINT "FAIR, LITTLE IN TEMP","FOR NEXT DAY OR TWO." 601 PAUSE 40000 602 GOTO 60 605 PRINT "FAIR TODAY, RAINY AND WARMER","WITHIN 48 HOURS" 606 PAUSE 40000 607 GOTO 60 610 PRINT "WARMER, RAIN WITHIN 18 TO 24","HOURS" 616 PAUSE 40000 617 GOTO 60 620 PRINT "CONTINUED FAIR WITH LITTLE","OR NO CHANGE IN TEMPERATURE" 621 PAUSE 40000 622 GOTO 60 625 PRINT "FAIR AND WARMER FOR NEXT 48 HOURS" 626 PAUSE 40000 627 GOTO 60 630 PRINT "RAIN WITHIN 24 HOURS" 631 PAUSE 40000 632 GOTO 60 635 PRINT "WINDY, WITH RAIN WITHIN 12","TO 24 HOURS" 636 PAUSE 40000 637 GOTO 60 640 PRINT "RAIN IN 12 TO 18 HOURS" 641 PAUSE 40000 642 GOTO 60 645 PRINT "WINDY AND RAIN WITHIN 12 HOURS" 646 PAUSE 40000 647 GOTO 60 650 PRINT "IN SUMMER WITH LIGHT WINDS: ","RAIN MAY NOT FALL FOR SEVERAL","DAYS" 651 PRINT "IN WINTER: RAIN WITHIN 24 HOURS" 652 PAUSE 40000 653 GOTO 60 655 PRINT "IN SUMMER RAIN LIKELY WITHIN","12 TO 24 HOURS" 656 PRINT ,,"IN WINTER: RAIN OR SNOW WITH INCREASING WINDS" 657 PAUSE 40000 658 GOTO 60 660 PRINT "RAIN FOR NEXT DAY OR TWO" 661 PAUSE 40000 662 GOTO 60 665 PRINT "RAIN, WITH HIGH WINDS FOLLOWED","WITHIN 24 HOURS BY CLEARING " 666 PRINT "AND TURNING COLDER" 667 PAUSE 40000 668 GOTO 60 670 PRINT "CLEARING WITHIN A FEW HOURS","FAIR FOR NEXT SEVERAL DAYS" 671 PAUSE 40000 672 GOTO 60 675 PRINT "%S%E%V%E%R%E% %S%T%O%R%M% %W%A%R%N%I%N%G","WINDY,WITH RAIN OR SNOW IMMINENT" 676 PRINT ,,"FOLLOWED WITHIN 24 HOURS BY","CLEARING AND COLDER" 677 PAUSE 40000 678 GOTO 60 680 PRINT "%S%E%V%E%R%E% %S%T%O%R%M% %W%A%R%N%I%N%G","SEVERE NORTHEAST GALES" 681 PRINT ,,"HEAVY RAIN OR SNOW, FOLLOWED IN WINTER BY A COLD WAVE" 682 PAUSE 40000 683 GOTO 60 685 PRINT "CLEARING AND COLDER" 686 PAUSE 40000 687 GOTO 60 700 CLS 705 FOR T=1 TO L 706 SCROLL 710 PRINT A$(T) 720 SCROLL 730 NEXT T 740 PAUSE 200 750 GOTO 60 900 CLS 905 PRINT " %W%E%A%T%H%E%R% %N%O%R%M%S" 925 PRINT 930 PRINT " TEMP" 935 PRINT " HI LO MO RAIN SNOW" 940 PRINT "J 38 23 30 2.83 9.1" 945 PRINT "F 41 24 32 2.70 9.6" 950 PRINT "M 51 31 41 3.19 6.5" 955 PRINT "A 64 42 53 3.02 0.3" 960 PRINT "M 75 52 63 3.61 0.0" 965 PRINT "J 83 61 72 3.61 0.0" 970 PRINT 975 PRINT "J 87 65 76 3.61 0.0" 980 PRINT "A 85 63 74 3.76 0.0" 985 PRINT "S 78 56 67 3.21 0.0" 990 PRINT "O 67 45 56 2.82 0.1" 995 PRINT "N 53 35 44 2.66 2.1" 1000 PRINT "D 40 25 33 2.94 7.7" 1005 PRINT 1010 PRINT "YR 63 43 53 37.96" 1015 PRINT 1020 PRINT "DATA FROM NWS HBG.,PA." 1025 PRINT " ELEVATION 338 FT." 1030 PAUSE 40000 1040 GOTO 60 2000 CLS 2001 FOR I=1 TO 10 2002 PRINT 2003 NEXT I 2005 PRINT " %W%E%A%T%H%E%R% %A%N%A%L%Y%S%I%S" 2040 PAUSE 400 2050 CLS 2055 PRINT "THIS PROGRAM IS DESIGNED TO","STORE A LIMITED AMOUNT OF DATA" 2056 PRINT "IN THE FILE PORTION OF THE","PROGRAM. IT IS SUGGESTED" 2057 PRINT "THAT FOR STORAGE OF MORE THAN ","SIX MONTHES A WEATHER FILE BE" 2058 PRINT "MANTAINED." 2060 PRINT 2065 PRINT "THIS PROGRAM WILL OFFER A","FORECAST OF EXPECTED LOCAL" 2066 PRINT "WEATHER CONDITIONS, USING","BAROMETRIC PRESSURE AND WIND" 2067 PRINT "DIRECTION",,,,"YOU WILL BE SURPRISED AT" 2068 PRINT "THE ACCURACY OF THIS METHOD,","YET IT IS BASED ON SOUND" 2069 PRINT "SCIENTIFIC PRINCIPLES." 2070 PRINT 2075 PRINT "%P%R%E%S%S% %A%N%Y% %K%E%Y% %T%O% %C%O%N%T%I%N%U%E" 2080 PAUSE 40000 2085 CLS 2090 RETURN 3000 CLS 3010 PRINT "ENTER DATE (AS 12-05-83)" 3015 INPUT B$(1,1 TO 8) 3018 FAST 3020 LET C$(1,1 TO 2)=B$(1,1 TO 2) 3025 LET C$(1,3 TO 4)=B$(1,4 TO 5) 3030 FOR A=1 TO L 3035 IF C$(1,1 TO 4)=A$(A,1 TO 4) THEN GOTO 3050 3040 NEXT A 3042 SLOW 3045 PRINT "%D%A%T%E% %N%O%T% %F%O%U%N%D" 3046 PAUSE 40000 3047 GOTO 60 3050 CLS 3055 SLOW 3066 PRINT "DATE: ";A$(A,1 TO 6) 3070 PRINT "HI TEMP: ";A$(A,7 TO 10) 3075 PRINT "LO TEMP: ";A$(A,11 TO 14) 3080 PRINT "BAROMETER: ";A$(A,15 TO 19) 3085 PRINT "CONDITION: ";A$(A,20) 3090 PRINT "PRECIPITATION: ";A$(A,21 TO 25) 3095 PRINT "SNOWFALL: ";A$(A,26 TO 27) 4000 PRINT "WINDS: ";A$(A,28 TO 31) 4010 PAUSE 40000 4020 GOTO 60 5000 CLS 5005 PRINT "ENTER DATE TO CHANGE:" 5010 INPUT B$(1,1 TO 8) 5011 LET C$(1,1 TO 2)=B$(1,1 TO 2) 5012 LET C$(1,3 TO 4)=B$(1,4 TO 5) 5015 FAST 5020 FOR N=1 TO L 5025 IF A$(N,1 TO 4)=C$(1,1 TO 4) THEN GOTO 5100 5030 NEXT N 5040 SLOW 5050 PRINT "DATE NOT IN FILE" 5055 PAUSE 40000 5060 GOTO 60 5100 CLS 5110 PRINT "ENTER: " 5120 PRINT TAB 5;"DATE (AS 6 DIGITS)"," (120583)" 5125 INPUT A$(N,1 TO 6) 5130 PRINT TAB 5;"HI TEMP" 5135 INPUT A$(N,7 TO 10) 5140 PRINT TAB 5;"LOW TEMP" 5145 INPUT A$(N,11 TO 14) 5150 PRINT TAB 5;"BAROMETER" 5155 INPUT A$(N,15 TO 19) 5160 PRINT TAB 5;"CONDITION" 5165 PRINT ,"1. FAIR",,"2. CLOUDY",,"3. RAIN",,"4. SNOW",,"5. THUNDERSHOWERS" 5167 PRINT ,"6. SNOW FLURRIES","7. HEAVY RAIN" 5170 INPUT A$(N,20) 5175 PRINT TAB 5;"RAIN" 5180 INPUT A$(N,21 TO 25) 5185 PRINT TAB 5;"WINDS" 5190 INPUT A$(N,28 TO 31) 5195 PRINT TAB 5;"SNOWFALL" 6000 INPUT A$(N,26 TO 27) 6005 LET X=N 6007 CLS 6010 GOTO 300 9000 SAVE "1024%3" 9010 RUN ```