---
title: "2068 Code Bytes #5"
type: "article"
slug: "2068-code-bytes-5"
url: "http://localhost/article/2068-code-bytes-5/"
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published_at: "2026-03-12T18:32:29+00:00"
modified_at: "2026-07-25T23:35:04+00:00"
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  url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg"
excerpt: "Fifth installment of the Z80 machine language series, presenting the world-map printing routine for CONQUEST. Covers FMO (find map start based on player position), PMAP (print map to screen), WRAP (horizontal and vertical wrapping logic for a 64x64 toroidal map), FINDAT (attribute address calculation), and PRUDG (print User Defined Graphic characters for map symbols). Full…"
category:
  - name: "SMUG Bytes"
    slug: "smug-bytes"
    taxonomy: "category"
    url: "http://localhost/category/periodicals/smug-bytes/"
post_tag:
  - name: "Best of Timex/Sinclair 2068 Articles and Documents"
    slug: "ts2068best"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts2068best/"
  - name: "Machine language programming"
    slug: "machine-language"
    taxonomy: "post_tag"
    url: "http://localhost/tag/machine-language/"
  - name: "TS 2068"
    slug: "ts2068"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts2068/"
  - name: "Type-in program"
    slug: "type-in-program"
    taxonomy: "post_tag"
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model:
  - name: "Timex/Sinclair 2068"
    slug: "ts-2068"
    taxonomy: "model"
    url: "http://localhost/model/ts-2068/"
indiv:
  - name: "Lloyd Dreger"
    slug: "lloyd-dreger"
    taxonomy: "indiv"
    url: "http://localhost/indiv/lloyd-dreger/"
publication_r:
  id: 37935
  title: "SMUG Bytes"
  type: "periodical"
  url: "http://localhost/periodical/smug-bytes/"
authors_r:
  - name: "Lloyd Dreger"
    slug: "lloyd-dreger"
    taxonomy: "indiv"
    url: "http://localhost/indiv/lloyd-dreger/"
volume: "10"
issue: "4-7"
issues_articles:
  - id: 50216
    title: "SMUG Bytes v10 n4-7"
    type: "issue"
    url: "http://localhost/issue/smug-bytes-v10-n4-7/"
pages: "3"
pubdate: "August - November 1993"
related_articles:
  - id: 64989
    title: "2068 Code Bytes #3"
    type: "article"
    url: "http://localhost/article/2068-code-bytes-3/"
  - id: 64991
    title: "2068 Code Bytes #4"
    type: "article"
    url: "http://localhost/article/2068-code-bytes-4/"
  - id: 64996
    title: "2068 Code Bytes #6"
    type: "article"
    url: "http://localhost/article/2068-code-bytes-6/"
  - id: 64998
    title: "2068 Code Bytes #7"
    type: "article"
    url: "http://localhost/article/2068-code-bytes-7/"
archive_link: false
---

# 2068 Code Bytes #5

Fifth installment of the Z80 machine language series, presenting the world-map printing routine for CONQUEST. Covers FMO (find map start based on player position), PMAP (print map to screen), WRAP (horizontal and vertical wrapping logic for a 64×64 toroidal map), FINDAT (attribute address calculation), and PRUDG (print User Defined Graphic characters for map symbols). Full assembly listings with addresses and mnemonics.

***

A routine to print a map that wraps in both directions, i.e., go off the map westward puts you on the eastern edge, northward on the southern edge or vise versa. The map itself is 64×64. We have two variables called Mapcox and Mapcoy (stored at 52396/7) which define what map coordinates (starting with 1,1) is being printed in the upper left corner of the screen. Since this routine also prints the player maps, it uses the variable Player (at 31539). The master map is stored at 32000. Each map requires 4096 bytes of space so player 1’s map starts at 36096, etc. We need a special variable called WRAPF (at 52389). The routine is entered at 60475 preceded by PMO which is a routine that finds the correct space in memory to start from.

The Findat routine depends upon how you set the various UDG characters on your map. For Conquest they are: 0 blank, 1 sea, 2 land, 3 mountain, 4 shoal, 5 city, 6-15 units whose color will be yellow, red and white for players 1 to 3 respectively. For cities and units ownership is designated in the top 2 bits.

We are running out of space so we will finish this routine in the next installment.

PLAYEREQU 31539from article prose

WRAPFEQU 52389from article prose

PRUDGEQU 60791printed at this address in issue #6

P1EQU 60726issue #6 resumes the listing here

MAPCOYEQU 52396issue #6 gives MAPCOX as 52397, so 52396 is MAPCOY

60442120PMOLD A,BBC=MAPCOX,MAPCOY

6044361DEC A

6044438,0LD H,0

60446167AND A

6044723RLA

6044823RLA

6044923RLA

60450203,20RL H

6045223RLA

60453203,20RL H

6045523RLA

60456203,20RL H

6045823RLAinserted per the correction in issue #6

60459203,20RL Hinserted per the correction in issue #6

60461111LD L,ATHE RIGHT STARTING POINT OF ANY MAP

NOW FIND OUT WHOS MAP

6046258,51,123LD A,(PLAYER)

60465167AND A

6046623RLA

6046723RLA

6046823RLA

6046923RLA

60470132ADD A,H

60471198,125ADD A,125ADD THE OFFSET TO MAP ZERO (MASTER)

60473103LD H,A

60474121LD A,C

6047561DEC A

60476133ADD A,L

60477111LD L,A

60478201RET

60479237,75,172,204PMAPLD BC,(MAPCOY)

60483205,26,236CALL PMO

60486175XOR A

6048750,165,204LD (WRAPF),ARESET WRAP FLAG

60490229PUSH HLSAVE HL ADDRESS FOR CALC. ATTR

6049117,0,64LD DE,16384SET DE TO TOP OF SCREEN

604946,3LD B,3WE ARE GOING TO PRINT ALL 24 LINES OF THE SCREEN, NOT JUST THE FIRST 21

60496197NEXTPUSH BCSAVE COUNT

6049714,8LD C,88 LINES

604996,32NEXT1LD B,3232/LINE

60501126NEXT2LD A,(HL)GET USER DEFINED CHARACTER

60502205,119,237CALL PRUDGPRUDG CONVERTS THE CHARACTER CODE TO THE CORRECT SPOT IN THE UDG TABLE AND PRINTS IT TO THE SCREEN

60505205,232,236CALL WRAPTHIS SUBROUTINE DOES THE ACTUAL DETERMINATION OF WHEN WE ARE AT A SEAM AND ADJUSTS HL ACCORDINGLY. A=WRAPF, 0=NO WRAP, 255=WRAP

60508254,255CP 255

6051032,8JR NZ,PM1

60512213PUSH DESAVE POINT ON SCREEN

6051317,64,0LD DE,64

60516167AND A

60517237,82SBC HL,DE

60519209POP DE

6052035PM1INC HLNOW RESET DE

60521122LD A,D

60522214,8SUB 8

6052487LD D,A

6052519INC DE

6052616,229DJNZ NEXT2

60528213PUSH DE

6052958,165,204LD A,(WRAPF)

60532254,0CP 0

6053440,5JR Z,AD-3AT END OF LINE WE HAVE TO ADD EITHER 96 OR 32 TO HL

6053617,96,0LD DE,96

6053924,3JR AD

6054117,32,0LD DE,32

6054425ADADD HL,DE

6054558,51,123LD A,(PLAYER)

60548167AND A

6054923RLA

6055023RLA

6055123RLA

6055223RLA

60553198,141ADD A,141

6055587LD D,A

60556124LD A,H

60557186CP D

6055832,3JR NZ,PM2RESET TO TOP OF MAP

60560214,16SUB 16

60562103LD H,A

60563209PM2POP DE

6056413DEC C

6056532,188JR NZ,NEXT1ADJUST DE TO NEXT SET OF 8

60567122LD A,D

60568198,7ADD A,7

6057087LD D,A

60571193POP BC

6057216,178DJNZ NEXT

NOW DO ATTRIBUTES

60574225POP HL

6057517,0,88LD DE,22528

6057814,24LD C,24

605806,32NEXT3LD B,32

60582197NEXT4PUSH BC

60583126LD A,(HL)

60584205,254,236CALL FINDATTHIS ROUTINE CALCULATES BOTH INK AND PAPER FOR THE CHARACTER AND STORES IT IN A

6058718LD (DE),A

60588205,232,236CALL WRAP

60591254,255CP 255

6059332,8JR NZ,NIX

60595213PUSH DE

6059617,64,0LD DE,64

60599167AND A

60600237,82SBC HL,DE

60602209POP DE

6060319NIXINC DE

6060435INC HL

60605193POP BC

6060616,230DJNZ NEXT4

60608213PUSH DE

6060958,165,204LD A,(WRAPF)

60612254,0CP 0

6061440,5JR Z,A1-3

6061617,96,0LD DE,96

6061924,3JR A1

6062117,32,0LD DE,32

6062425A1ADD HL,DE

6062558,51,123LD A,(PLAYER)

60628167AND A

6062923RLA

6063023RLA

6063123RLA

6063223RLA

60633198,141ADD A,141

6063587LD D,A

60636124LD A,H

60637186CP D

6063832,3JR NZ, PR3

60640216,16SUB 16

60642103LD H,A

60643209PR3POP DE

6064413DEC C

6064532,189JR NZ,NEXT3

60647201RET

60648125WRAPLD A,L

60649254,63CP 63NOTE: 63, 127, 191 AND 255 FOR L INDICATE THE EASTERN EDGE OF THE MAP

6065140,11JR Z,CONT

60653254,127CP 127

6065540,7JR Z,CONT

60657254,191CP 191

6065940,3JR Z,CONT

60661254,255CP 255

60663192RET NZ

6066462,255CONTLD A,255

6066650,165,204LD (WRAPF),A

60669201RET

60670254,0FINDATCP 0

6067232,3JR NZ,AT1

6067462,7LD A,7P=BK,I=W

60676201RET

60677254,1AT1CP 1

6067932,3JR NZ,AT2

6068162,15LD A,15P=BL,I=W

60683201RET

60684254,4AT2CP 4

6068648,3JR NC,AT4

6068862,32LD A,32P=GR,I=BK

60690201RET

60691254,4AT4CP 4

6069332,3JR NZ,AT5

6069562,41LD A,41P=AQ,I=BL

60697201RET

60698254,5AT5CP 5

6070032,3JR NZ,C2

6070262,59LD A,59P=W,I=MG

60704201RET

60705254,69C2CP 69PLAYER1?

6070732,3JR NZ,C3

6070962,48LD A,48P=BK,I=Y

60711201RET

60712254,133C3CP 133PLAYER2?

6071432,3JR NZ,C4

6071662,16LD A,16P=BK,I=R

60718201RET

60719254,197CP 197PLAYER3?

6072132,3JR NZ,P1

6072362,56LD A,56P=BK,I=W

60725201RETprinted at 60721 in issue #5; two bytes at the previous line put it here

***

#### About this transcription

This listing was transcribed from the original scan and checked line by line. The published address column, object-byte column and mnemonics each independently determine the program, so all three were cross-referenced against one another: 173 lines carried both bytes and mnemonics and were cross-checked against each other.

2 lines could not be reconciled: the address, byte and mnemonic columns disagree, so the listing as printed cannot be correct at these points. Which column is at fault is noted in each case.

- **60640**, should read `214,16` — 216 is RET C, a single byte; the parallel code at 60560 prints 214,16 and the address column requires two bytes here. Not covered by the correction in issue #6
- **60714**, printed as `JR NZ,C4` — the label C4 belongs on line 60719, which is printed without it; the jump itself is correct

Anyone typing this listing in should expect to work through these before it will run, and should treat the surrounding code with some caution: where a listing has demonstrably been disturbed in one place, quieter faults elsewhere are plausible even though nothing here detected them.