Decompiled Source

Ren14500 has been building a phenomenally good disassembler to start taking apart system source files and turn them into genuine Centurion assembly. The resulting assembly is accurate enough that it can be reassembled using P.ASM. We do not have the source code for the original Operating System, so this is as close as we can get to peering into the inner workings and seeing how things function.

Example (XSMCB)

This is a decompiled example of the executable "XSMCB." The "X" stands for "eXecutable" and "SMCB" stands for "Set Mux Control Byte."

* Label naming:
* ENTRY = Main entry point
* ENTnn = Additional entry point
* B = Byte
* D = Displaced branch/jump target
* F = Function JSR target
* I = 32-bit integer
* J = Jump target
* L = Label (generic)
* N = Bignum
* P = Pointer
* S = String
* W = Word
*
8000:      DB    0,100      ; =0x00,0x0064
*
* Function ENTRY
*
8064:ENTRY XFR=  ENTRY,S    ; =0x8064 =32868(-32668) [Transfer immediate to S]
8068:      SVC   X'5C'      ; =92 [Service call GBKV - get OS block value]
806a:      DB    X'00'      ; =0x00 =0 =NUL [TODO: arg1]
806b:      DB    X'01'      ; =0x01 =1 [TODO: arg2]
806c:      DB    X'15'      ; =0x15 =21 [TODO: arg3]
806d:W806D DW    W806D      ; =0x806d =32877(-32659) [address to store block value]
806f:      LDB=  W807C      ; =0x807c =32892(-32644) [Load B with immediate]
8072:      SVC   X'5D'      ; =93 [Service call PBKV - set OS block value]
8074:      DW    X'0101'    ; =0x0101 =257 [TODO: arg1]
8076:      DB    X'19'      ; =0x19 =25 [TODO: arg2]
8077:      DW    W806D      ; =0x806d =32877(-32659) [address to read block value]
8079:      SVC   X'0A'      ; =10 [Service call EXIT - exit to OJX00]
807b:      DB    X'FF'      ; =0xff =255(-1) [completion code]
*
807c:W807C DW    X'0000'    ; =0x0000 =0 =NUL,NUL
807e:ENDPT

Decompiled Files

Boot

File	Notes	Link
CPU4 Autoload	ROM located on DSK/AUT board to bootstrap CPU4 systems	Link
CPU5 Early Bootstrap	ROM located on Backplane to bootstrap CPU5 systems off the Hawk Drive	Link
CPU5 Late Bootstrap	ROM located on Backplane to bootstrap CPU5 systems off the Hawk Drive	Link
CPU6 Bootstrap	ROM located on Backplane to bootstrap CPU6 systems to D= prompt	Link
FDIPL	Warrex Initial Program Loader unique to the floppy drive	Link
CPU5 WIPL	CPU5 Warrex Initial Program Loader	Link
CPU6 WIPL	CPU6 Warrex Initial Program Loader	Link

CPU5 OpSys

File	Notes	Link
XPDIR	Essential part of CPU5 OpSys	Link

CPU6 OpSys

File	Notes	Link
OJX00	Main JCL parser. Prints "CRT0 READY", launches other @OJX files	Link
OJX02	JCL command `.FSPEC` and `.DSPEC`	Link
OJX03	JCL command `.STA`	Link
OJX04	JCL `.START, .STOP, .LOG, .NOLOG, .PRI, .TIME, .NOTIME, .DUMP, .NODUMP, .MULTP`	Link
OJX07	JCL command `.IOA`	Link
OJX11	JCL command `.FORMAT`	Link
OJX16	JCL command `.REL` and `.CODE`	Link
OJX17	JCL command `.SETA` and `.SETC`	Link
OJX18	JCL command `.SKIP` and `.SKIPR`	Link
OJX19	JCL command `.JOB` and `.PARM`	Link
OJX23	JCL command `.VOL` and `.VSPEC`	Link
OJX24	JCL command `.PAUSE, .ENTER, .GUARD, .NOGUARD`	Link
TX002	OpSys transient file:	Link
TX003	OpSys transient file:	Link
TX004	OpSys transient file: get string date	Link
TX009	OpSys transient file: load private library	Link
TX010	OpSys transient file: get integer date	Link
TX011	OpSys transient file: convert date in GRIN to INTEGER	Link
TX012	OpSys transient file: gets the current date of a file into the A register	Link
TX013	OpSys transient file: sets the date on a file from the A register	Link
TX014	OpSys transient file: open file by name/disk	Link
TX015	OpSys transient file: performs low level disk I/O	Link
PD000	OpSys predriver for MUX terminal	Link
PD001	OpSys predriver for MUX terminal	Link
PD002	OpSys predriver for MUX terminal	Link
PD003	OpSys predriver for MUX terminal	Link
PD004	OpSys predriver for MUX terminal	Link
PD005	OpSys predriver for MUX terminal	Link
PD006	OpSys predriver for MUX terminal	Link

P Folder Assembler/Compiler Related

File	Notes	Link
OSLIB6	Implements a variety of CPL functions (LEN, MOD, MIN, MAX, etc.), as well as other useful functions	Link

Executables

File	Notes	Link
BASIC Monitor	Called to load the BASIC monitor to allow BASIC executables to run	Link
KOMPOZ	Executable for the KOMPOZ text editor	Link
XASSM	Assembler that builds CPU6 machine code from Assembly code	Link
XASSM5	Assembler that builds CPU5 machine code from Assembly code	Link
XBCOM	Called to compile a BASIC program into pseudocode	Link
XEJECT	Simply clears the screen	Link
XHEXLST	Hexadecimal viewer	Link
XLINK	Interactive linker used when compiling executables	Link
XSDUMP	Hex dumper and editor	Link
ZSDUMP	Recreated CPL source code for XSDUMP	Link
XSMCB	Sets the control byte of the MUX board to change baud rate, data, etc.	Link