Osborne 1 disassembly of BIOS and PROMS

Th堠 file OsBIOS.DOC OsBIOS.SY͠ an OsBIOS.CT̠ contai 
informatio t generat disassemblie o Osborn  BIOӠ an 
PROMS Thes ca b use i conjuntio wit Z8 derivative o 
War Christensen' RESOURCŠ disassemble (e.g ZESOURCŠ o 
REZILOG t regenerat th sourc cod fo th Osborne' Basi 
Inpu Outpu System includin th pro part Als required  
course i a Osborn computer Fo reason o copyrigh 
protectio o thi proprietar software i i no allowe t 
distibute the actual disassembled instructions.

Th conten o OsBIOS.DOC/SYM/CT an TX ar cyrigh Fran Va 
Duinen 1982 an ma b freel distributed Commercia us i 
expressl prohibited Anyon explorin thes innermos an 
darkes Secret O Th Osborne,i encourage t pu tha 
informatio bac o th Bulleti Boards.

T disassebl th BIO par o th Osborne' CP/ system whic 
is in RAM memory from E500(Hex) to EFFFH, proceed as follows:
o load REZILOG or ZESOURCE disassembler
o u7000   - reserve space for comments (.DOC) file
o rOsBIOS.all - read all three of .DOC, .SYM & .CTL
  use rOsBIOS.ctl
      rOsBIOS.sym
      rOsBIOS.doc  for REZILOG (does not allow all)
o ^P  - to turn on printer, and
o le500,f000 to list to printer, or use
o sOsBIOS.asm   - to open assembly output file,
o pe500,f000    - generate prolog (ORG & EQU)
o le500,f000    - to disassemble to file
                  th en statemen a f00 wil automatcall 
                  cause the file to be closed
     
T disassembl ROM th cod  RO firs ha t b copie t th 
RA͠ memor ban (se pag 259-26 o th Osborn manual) Thi 
require  progra tha reside i memor abv 4000H an ban 
switche a outlne o p 261,26 o th manual Thi copie cod 
mus the b save t  fil name xxx.CO (e.g PROMS.COM) Thi 
fil ca the b rea i an processe b th disassembler 
Ther i  program OSROM.ASM/COM o variou BulletinBoards 
that provides such a ROM copy facility.

T disassembl PROMS.COM us th followin step unde 
ZESOURCE/REZILOG:
o u7000
o rOsBIS.all
 O4f0  - loa objec cod a offse 4f0 o it norma locatio 
           (RESOURC et assum 100 a th norma start howeve 
           the ROM code starts at 0)
o rPROMSCOM  - read incpy of ROM object code
o O5000   - adjust offset to allow start at 0
o l0,e8d  - to list the disassembled ROM code
o SPROMS.asm  - to open assembly output file
 ce8d,    - defin en entr t generat ENĠ statemen o               assembly
o p0,e8d      - to generate prologue & EQU statements
o l0,ffff     - to list disassembled code to the file
              th EN statemen a e8 wil automaticall clos 
              the file.

T d furthe work ge th documentatio o Ward' excellen 
disassemble (RESOURCE) and/o it derivatives Thi 
documentati probabl exist o  loca CP/ boar unde th nam 
RESOURCE.DOà o RESOURCE.HLP Whe usin ZESOUC watc ou fo 
the bugs:
K (kll) command does not work
; (comment) lines over 80 characters crash the system,
; may hang the system
& ZESOURCE occasionally clobbers the .DOC file.
REZILOǠ seem t wor fine bu lack som nic tuche tha 
ZESOURCŠ provide (r...al  automati kil o  command) 
REZILOǠ doe provid som othe features notabl th  an  
cmands and, of course, the more intelligible Zilog mnemonics.

Wel, have fun with this one,  Frans Van Duinen, July 1982.
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