SuperCheck

Keeps a running checking-account balance from records stored in the program’s own DATA lines. Each record holds a date, a type code, an amount and a remark. At the prompt you enter part of a date to list matching entries, such as the first characters of a month, a full date to pull a single entry, or just ENTER for everything; the program prints each matching record with its effect on the balance, then a “TOTAL USABLE BALANCE” that flashes in red if it is zero or below. Everything shown on screen is also sent to the printer.

The title screen reads “CHECKING BALANCE” preceded by its owner’s first name, and the program saves itself as checkbal or ck; “SuperCheck” is the name in the tape header. A reminder screen lists the codes: BAL, CHG and V/d go in the type field, MONTH in the date field and VOID in the remark.

Program Analysis

Program Structure

• Lines 100–410: colours, two 100-element arrays and the title and code reminder, sent to the printer as well.
• Lines 500–525: the search prompt and column headings.
• Lines 600–740: the main loop, which reads a record, adjusts its amount by type and prints it if the search string occurs anywhere in its date.
• Lines 800–850: the total.
• Lines 1000–8998: the records, ended by a record whose date is "z".
• Line 9999: saves the program with LINE 0, verifies it and reruns.

How amounts are counted

Line 611 turns every amount into a debit and takes off 30 cents more, apparently a per-check charge. Lines 612–617 then correct this by type: a BAL (balance brought forward) or V/d entry becomes a credit at face value, a CHG (bank charge) is debited without the extra 30 cents, a V/w entry carries a 15-cent charge instead, and a VOID remark refunds the 30 cents. A MONTH record sets its own amount to zero and restarts the running total, and the total is rounded to cents at line 731.

Notable Techniques

• The search is a substring match over the date field (a$(s TO s+x-1)), so an empty search string matches every record.
• Typing the STOP keyword at the prompt ends the program (line 504).
• POKE 23692,255 before each record keeps the screen from stopping with “scroll?” during a long listing.

Potential Issues

• After the total, the program runs straight on into line 999 SAVE "checkbal", so every report ends with a request to save the program.
• GO TO 700 at line 650 targets a line that doesn’t exist; it lands on line 710, which works.
• Only c(1) is ever used, since c stays 1 (LET c=c at line 730 does nothing), and the array b() is never used.
• The printed column heading says “DUE:” where the screen says “CHECK:”.
• New records have to be typed in as DATA lines, and the program’s own DATA holds the last owner’s entries.