---
title: "Business #4"
id: 56667
type: "computer_media"
slug: "boss-t1503"
url: "http://localhost/computer_media/boss-t1503/"
markdown_url: "http://localhost/computer_media/boss-t1503.md"
published_at: "2024-09-22T23:31:36+00:00"
modified_at: "2026-04-03T07:59:03+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2024/09/BrkEvn.png"
excerpt: "Two business tools in one listing: a break-even analyser with printer support and a job quote estimator that itemises labour, materials, overhead, and profit in a formatted schedule."
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: "S & S Company"
    slug: "s-s-company-the"
    taxonomy: "post_tag"
    url: "http://localhost/tag/s-s-company-the/"
  - 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: "Business"
    slug: "business"
    taxonomy: "genre"
    url: "http://localhost/type/business/"
media_type: "Cassette"
download_url: "https://archive.org/download/timex-sinclair-software-archive/Boss%20T1503%20%28198X%29%28BOSS%29%28TS1000%29%28US%29%28Program%29.zip"
mediadate: "198X"
producer_company:
  - id: 11258
    title: "S & S Company, The"
    type: "company"
    url: "http://localhost/company/s-s-company-the/"
images:
  - url: "http://localhost/wp-content/uploads/2024/09/BrkEvn.png"
  - url: "http://localhost/wp-content/uploads/2024/09/Quote.png"
  - url: "http://localhost/wp-content/uploads/2024/09/Tape-3.jpg"
related_products:
  - id: 12003
    title: "Business #4"
    type: "product"
    url: "http://localhost/product/business-4/"
media_type_tags: "Business"
---

# Business #4

This listing contains two independent business finance programs. The first performs break-even analysis, prompting the user for fixed costs, variable parts cost per unit, selling price, starting and finishing stock quantities, and an increment step, then printing a columnar cost/revenue/profit-loss schedule with a clearly marked break-even row; it supports optional hard-copy output via LPRINT. The second program is a job quote estimator that collects materials, shop labour, and on-site labour costs (each optionally itemised line-by-line), then computes overhead and profit as user-supplied percentages and prints a formatted multi-column estimate summary, with a COPY command triggered by pressing Z to produce a printer dump. Both programs use SCROLL extensively to manage the ZX81’s 24-row display in SLOW mode, switch to FAST mode for computation-heavy sections, and round currency values using the INT(100*x+0.05)/100 idiom for two-decimal-place accuracy. The itemised entry subroutine at line 1200 is shared between the materials, shop labour, and on-site labour collection paths in the second program.

***

## Program Analysis

The listing contains two completely independent programs separated by their own `SAVE` and `RUN` tail lines. The first (lines 10–9999) is a break-even analysis tool. The second (lines 10–9999, restarting) is a job quotation estimator. They are analysed separately below.

### Program 1 – Break-Even Analysis: Structure

The program is entirely linear with no subroutines. It collects six inputs (fixed costs `F`, variable cost per unit `V`, selling price `P`, start quantity `B`, finish quantity `C`, and increment `S`), then iterates from `B` to `C` in steps of `S`, printing a cost/revenue table. At line 460–480 the break-even quantity `D`, break-even revenue `G`, and break-even cost `H` are calculated before the loop begins.

1. **Input phase** (lines 70–410): six prompted `INPUT` statements, each followed by confirmation `PRINT` and `SCROLL` pairs.
2. **Hard-copy option** (lines 432–457): asks for `Y$`; any line thereafter guarded by `IF Y$(1)="Y"` duplicates output to the printer via `LPRINT`.
3. **Computation and output loop** (lines 530–1030): `FOR N=B TO C STEP S`; at line 580 a test `IF N<D` branches to 1000 (skipping the break-even banner), otherwise prints the separator, break-even row, and resets `D=99999999` so the banner fires only once.
4. **Recycle** (lines 2000–2060): waits for any keypress then `RUN`s from the top.

### Program 1 – Notable Techniques and Idioms

- **FAST/SLOW switching**: `FAST` at line 420 speeds up the CLS and setup; `SLOW` at line 510 restores display before the output loop so results are visible as they scroll.
- **One-shot break-even banner**: after printing the break-even row (lines 590–640), `D` is set to `99999999` (line 650) so the condition at line 580 never triggers again within the same run.
- **Zero-start guard**: line 520 prevents a division-by-zero in `U=E/N` when `B=0` by advancing `B` to `S`.
- **Unit-cost rounding**: line 565 applies `INT(10*U+.5)/10` — rounding to one decimal place.
- **Busy-wait keypress**: lines 2030–2040 use the `INKEY$` polling loop, a standard ZX81 idiom.
- **LPRINT mirroring**: every significant `PRINT` in the output phase has a corresponding `IF Y$(1)="Y" THEN LPRINT` guard, doubling the line count but keeping hard-copy output structurally identical to screen output.

### Program 1 – Bugs and Anomalies

- At line 9998 the filename contains an inverse `N` mid-word, which is the auto-run marker embedded in the filename string.
- The `LPRINT` column footer at line 1060 contains leading spaces rather than using `TAB`, so alignment may drift slightly depending on printer character width.
- If `P=V` (selling price equals variable cost), line 460 will cause a division-by-zero error as there is no guard.

### Program 2 – Job Quote Estimator: Structure

This program uses a counter `D` (line 20, incremented at line 205) to number successive estimates within a session. Three subroutine groups handle data collection and output:

| Line range | Purpose |
| --- | --- |
| 1000–1190 | Material cost collection: dispatch to itemised (1200) or total-entry path |
| 1200–1670 | Generic line-item entry loop (shared by materials, shop labour, on-site labour) |
| 2000–2550 | Labour cost collection: shop labour then on-site labour, each optionally itemised |
| 3000–3290 | Quote summary display and optional COPY dump |

### Program 2 – The Shared Itemisation Subroutine (line 1200)

Subroutine 1200 is called three times: for materials (line 1150), shop labour (line 2115), and on-site labour (line 2340). It accumulates a running total in `C`, collecting item name `B$`, unit cost `A`, and quantity `G` in a loop. An empty `B$` input (line 1255) terminates entry and returns the total in `C`. The caller then copies `C` into the appropriate variable (`M`, `L`, or `H`).

### Program 2 – Financial Calculations

All monetary arithmetic is done in floating point and then rounded. The main formula chain (lines 550–640):

- `B = Q*M` — total material cost (units × per-unit material)
- `K = Q*L` — total shop labour
- `J = H*Q` — total on-site labour
- `V = O*(L+H)` — overhead per unit (percentage of direct labour only)
- `W = V*Q` — total overhead
- `R = P*(B+K+J+W)` — total profit (percentage of total job cost excluding profit itself)
- `S = B+K+J+R+W` — total quote
- `T = S/Q`, `X = R/Q` — per-unit equivalents

Note that overhead is calculated on direct labour only (`L+H`), not on materials, which is a deliberate business convention reflected in line 590.

### Program 2 – Currency Rounding Idiom

Throughout the summary subroutine (lines 3102–3256), values are rounded to two decimal places using `INT(100*x+.05)/100`. The bias of 0.05 (rather than the standard 0.5 used in program 1’s line 565) is slightly too small — correct two-decimal rounding requires `+0.005` — so values near half-penny boundaries may round down incorrectly. The same pattern appears in the itemisation loop at line 1455.

### Program 2 – COPY Dump Mechanism

The summary subroutine ends with a `PAUSE 40000` (line 3270) giving the user approximately 40 seconds to press Z. Line 3280 tests `INKEY$="Z"` immediately after the pause expires or the user presses a key; if Z was the key that broke the pause, `COPY` is executed to dump the screen to a printer. This is a common ZX81 screen-print idiom since `COPY` sends the full display bitmap to the printer port.

### Program 2 – Anomalies

- Line 2130 uses `GOTO 2240` rather than `RETURN` after setting `L=C`, skipping the corresponding `RETURN` at line 2230 (which does not exist). This means execution falls through to line 2240 correctly but is structurally fragile.
- “INSTALATIONS” is misspelled at line 3080 (missing one L), as it is at line 300 in the input phase.
- Variable `C` is overloaded: it holds the overhead percentage input at line 410 and is also the running item total inside subroutine 1200. The overhead percentage is safely converted to `O=C/100` at line 430 before any subroutine call, so there is no collision in practice, but the summary at line 3200 prints `C` as the overhead percentage label — which by that point still holds the last value from the itemisation loop, not the original percentage. This is a latent display bug.
- The `GOTO 100` at line 690 re-enters the main loop but does not reinitialise `D`, so the estimate counter correctly increments across quotes in a session.

## Source Code

```
  10 PRINT AT 10,6;"BREAK-EVEN  ANALYSIS"
  20 PRINT ,,"PRODUCES COSTS/REVENUE SCHEDULES"
  30 PAUSE 200
  40 FOR N=1 TO 6
  50 SCROLL 
  60 NEXT N
  70 PRINT "WHAT ARE THE FIXED COSTS?"
  80 INPUT F
  90 SCROLL 
 100 PRINT ,F
 110 SCROLL 
 120 SCROLL 
 130 PRINT "WHAT IS THE PARTS COST PER UNIT?"
 140 INPUT V
 150 SCROLL 
 160 PRINT ,V
 170 SCROLL 
 180 SCROLL 
 190 PRINT "WHAT IS THE UNIT SELLING COST?"
 200 INPUT P
 210 SCROLL 
 220 PRINT ,P
 230 SCROLL 
 240 SCROLL 
 250 PRINT "UNITS IN STOCK AT START?"
 260 INPUT B
 270 SCROLL 
 280 PRINT ,B
 290 SCROLL 
 300 SCROLL 
 310 PRINT "UNITS IN STOCK AT FINISH?"
 320 INPUT C
 330 SCROLL 
 340 PRINT ,C
 350 SCROLL 
 360 SCROLL 
 370 PRINT "ANALYSIS INCREMENT NUMBER?"
 380 INPUT S
 390 SCROLL 
 400 PRINT ,S
 410 PAUSE 200
 420 FAST 
 430 CLS 
 432 PRINT ,,"DO YOU WANT HARD COPY?"
 434 INPUT Y$
 440 SCROLL 
 450 PRINT "QUANT COST  REV   P/L   UN COST"
 455 IF Y$(1)="Y" THEN LPRINT "QUANT COST  REV   P/L   UN COST"
 457 IF Y$(1)="Y" THEN LPRINT 
 460 LET D=F/(P-V)
 470 LET G=P*D
 480 LET H=F+V*D
 490 SCROLL 
 500 SCROLL 
 510 SLOW 
 520 IF B=0 THEN LET B=B+S
 530 FOR N=B TO C STEP S
 540 LET R=P*N
 550 LET E=F+V*N
 560 LET U=E/N
 565 LET U=INT (10*U+.5)/10
 570 LET A=R-E
 580 IF N<D THEN GOTO 1000
 590 PRINT "--------------------------------"
 595 IF Y$(1)="Y" THEN LPRINT "--------------------------------"
 600 SCROLL 
 610 PRINT INT D;TAB 6;INT H;TAB 12;INT G;TAB 18;"BREAK-EVEN"
 613 SCROLL 
 615 IF Y$(1)="Y" THEN LPRINT INT D;TAB 6;INT H;TAB 12;INT G;TAB 18;"BREAK-EVEN"
 620 SCROLL 
 630 PRINT "--------------------------------"
 635 IF Y$(1)="Y" THEN LPRINT "--------------------------------"
 640 SCROLL 
 650 LET D=99999999
 1000 PRINT N;TAB 6;E;TAB 12;R;TAB 18;A;TAB 24;U
 1003 SCROLL 
 1005 IF Y$(1)="Y" THEN LPRINT N;TAB 6;E;TAB 12;R;TAB 18;A;TAB 24;U
 1010 SCROLL 
 1020 SCROLL 
 1030 NEXT N
 1040 SCROLL 
 1050 SCROLL 
 1060 IF Y$(1)="Y" THEN LPRINT "                                QUANT COST  REV   P/L   UN COST"
 2000 SCROLL 
 2010 SCROLL 
 2020 PRINT "PRESS ENTER TO RECYCLE :::"
 2030 LET Y$=INKEY$
 2040 IF Y$="" THEN GOTO 2040
 2050 CLS 
 2060 RUN 
 9998 SAVE "BREAK EVE%N"
 9999 RUN 
 
  10 CLS 
  20 LET D=0
 100 CLS 
 110 PRINT AT 12,0;" %*%*%*% %J%O%B% %Q%U%O%T%E% %E%S%T%I%M%A%T%E%R% %*%*%*"
 200 SCROLL 
 205 LET D=D+1
 210 PRINT "   PRESS ENTER TO START :::"
 220 INPUT Y$
 230 CLS 
 240 SCROLL 
 250 PRINT "JOB NAME?  ";
 260 INPUT N$
 270 PRINT N$
 280 SCROLL 
 290 SCROLL 
 300 PRINT "NUMBER OF INSTALLATIONS?"
 310 SCROLL 
 320 INPUT Q
 330 PRINT ,Q
 340 SCROLL 
 350 SCROLL 
 360 GOSUB 1000
 370 GOSUB 2000
 380 SCROLL 
 390 PRINT "OVERHEAD (PER. OF DIRECT LABOR)?"
 400 SCROLL 
 410 INPUT C
 420 SCROLL 
 425 PRINT ,C
 426 SCROLL 
 430 LET O=C/100
 440 SCROLL 
 450 PRINT "PROFIT (PER OF JOB COST)?"
 460 SCROLL 
 470 INPUT Z
 480 PRINT ,Z
 490 SCROLL 
 500 SCROLL 
 510 LET P=Z/100
 520 PRINT "PRESS ENTER TO SEE QUOTE :::"
 530 INPUT Y$
 540 CLS 
 550 LET B=Q*M
 560 LET K=Q*L
 570 LET J=H*Q
 590 LET V=O*(L+H)
 600 LET W=V*Q
 610 LET R=P*(B+K+J+W)
 620 LET X=R/Q
 630 LET S=B+K+J+R+W
 640 LET T=S/Q
 650 GOSUB 3000
 660 SCROLL 
 665 SCROLL 
 670 PRINT "PRESS ENTER FOR ANOTHER QUOTE ::"
 680 INPUT Y$
 690 GOTO 100
 1000 PRINT "ARE MATERIAL COSTS TO BE"
 1010 SCROLL 
 1020 PRINT "ITEMIZED (Y/N)?"
 1030 SCROLL 
 1040 INPUT B$
 1050 IF B$(1)="Y" THEN GOTO 1100
 1060 IF B$(1)="N" THEN GOTO 1160
 1070 GOTO 1040
 1100 SCROLL 
 1110 SCROLL 
 1120 PRINT "MATERIAL COSTS :::"
 1130 SCROLL 
 1140 SCROLL 
 1150 GOSUB 1200
 1155 LET M=C
 1156 RETURN 
 1160 SCROLL 
 1170 SCROLL 
 1180 PRINT "TOTAL MATERIAL COST?  ";
 1184 INPUT M
 1186 PRINT M
 1188 SCROLL 
 1190 RETURN 
 1200 LET C=0
 1205 SCROLL 
 1210 PRINT "ESTIMATE NO.";D
 1220 SCROLL 
 1230 SCROLL 
 1240 PRINT "ITEM?",
 1250 INPUT B$
 1255 IF B$="" THEN GOTO 1600
 1260 PRINT B$
 1270 SCROLL 
 1280 SCROLL 
 1290 PRINT "COST?",
 1300 INPUT A
 1310 PRINT A
 1320 SCROLL 
 1340 SCROLL 
 1350 PRINT "QUANTITY?",
 1360 INPUT G
 1370 PRINT G
 1380 LET E=A*G
 1390 SCROLL 
 1400 SCROLL 
 1410 SCROLL 
 1430 PRINT "ITEM    COST    QUANT   EXTEND"
 1440 SCROLL 
 1450 SCROLL 
 1455 LET E=INT (100*E+.05)/100
 1460 PRINT B$;TAB 8;A;TAB 16;G;TAB 24;E
 1470 SCROLL 
 1480 SCROLL 
 1490 LET C=C+E
 1500 GOTO 1220
 1600 SCROLL 
 1605 SCROLL 
 1610 PRINT "TOTAL",C
 1620 SCROLL 
 1630 SCROLL 
 1640 PRINT "PRESS ENTER TO CONTINUE :::"
 1650 INPUT B$
 1660 CLS 
 1670 RETURN 
 2000 SCROLL 
 2010 SCROLL 
 2020 PRINT "DO YOU WANT SHOP LABOR ITEMIZED?"
 2030 INPUT Y$
 2040 IF Y$(1)="N" THEN GOTO 2140
 2050 IF Y$(1)="Y" THEN GOTO 2070
 2060 GOTO 2030
 2070 SCROLL 
 2080 SCROLL 
 2090 PRINT "SHOP LABOR PER HOUR"
 2100 SCROLL 
 2110 SCROLL 
 2115 GOSUB 1200
 2120 LET L=C
 2130 GOTO 2240
 2140 SCROLL 
 2150 SCROLL 
 2160 PRINT "COST FOR TOTAL SHOP LABOR?"
 2170 SCROLL 
 2180 SCROLL 
 2190 INPUT L
 2200 PRINT ,L
 2210 SCROLL 
 2240 SCROLL 
 2260 PRINT "ON SITE LABOR TO BE ITEMIZED?"
 2270 SCROLL 
 2280 INPUT B$
 2290 IF B$(1)="Y" THEN GOTO 2320
 2300 IF B$(1)="N" THEN GOTO 2500
 2310 GOTO 2280
 2320 CLS 
 2330 PRINT ,,"ON SITE LABOR PER HOUR :::"
 2340 GOSUB 1200
 2350 LET H=C
 2360 RETURN 
 2500 SCROLL 
 2510 SCROLL 
 2520 PRINT "ON SITE LABOR TOTAL COST?"
 2530 INPUT H
 2540 SCROLL 
 2550 RETURN 
 3000 SCROLL 
 3010 SCROLL 
 3020 PRINT "NAME   ";N$;TAB 16;"ESTIMATE ";D
 3030 SCROLL 
 3040 SCROLL 
 3050 PRINT "EST PAR    NO. UNITS    EXTENDED"
 3060 SCROLL 
 3070 SCROLL 
 3080 PRINT "NUMBER OF INSTALATIONS   ";Q
 3090 SCROLL 
 3100 SCROLL 
 3102 LET M=INT (100*M+.05)/100
 3104 LET B=INT (100*B+.05)/100
 3110 PRINT "MATERIAL COST ";M;TAB 25;B
 3120 SCROLL 
 3130 SCROLL 
 3132 LET L=INT (100*L+.05)/100
 3134 LET K=INT (100*K+.05)/100
 3140 PRINT "SHOP LAB COST ";L;TAB 25;K
 3150 SCROLL 
 3160 SCROLL 
 3162 LET H=INT (100*H+.05)/100
 3164 LET J=INT (100*J+.05)/100
 3170 PRINT "SITE LAB COST ";H;TAB 25;J
 3180 SCROLL 
 3190 SCROLL 
 3195 LET W=INT (100*W+.05)/100
 3196 LET V=INT (100*V+.05)/100
 3200 PRINT "OVRHD";" (";C;")";TAB 14;V;TAB 25;W
 3210 SCROLL 
 3220 SCROLL 
 3225 LET R=INT (100*R+.05)/100
 3226 LET X=INT (100*X+.05)/100
 3230 PRINT "PROFIT";" (";Z;")";TAB 14;X;TAB 25;R
 3240 SCROLL 
 3250 SCROLL 
 3255 LET S=INT (100*S+.05)/100
 3256 LET T=INT (100*T+.05)/100
 3260 PRINT "JOB QUOTE";TAB 14;T;TAB 25;S
 3262 SCROLL 
 3263 SCROLL 
 3265 PRINT AT 21,0;"PRESS <Z> FOR COPY ::"
 3270 PAUSE 40000
 3275 PRINT AT 21,0;"                     "
 3280 IF INKEY$="Z" THEN COPY 
 3290 RETURN 
 9998 SAVE "QUOT%E"
 9999 RUN
```