- LongSack
- Jan 17, 2003
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Let's see some seriously old stuff here.
My contribution:
SPL (Systems Programming Language)
Architecture - HP/3000
Date - 1984
The HP/3000 minicomputers were a stack-based architecture with some special purpose registers:
- S register = TOS (Top Of Stack)
- Q register was current procedure relative, so that procedure parameters were stored at Q-4 ... Q-x and local variables were stored at Q+0 ... Q+y
- DB register was Global procedure relative, so that global variables were stored at DB+x (and magic stuff only available to Privileged Mode code was stored at DB-x)
Memory was divided into 64K banks of 16-bit words (128K bytes). Code was relatively small since much of the functionality was encoded into Shared Libraries (SL).
SPL was an Algol-based language which had special features designed for writing low level code for the HP/3000 machines, like an "ASSEMBLE(...)" statement that allowed the emitting of assemble code.
Here is the code for a routine that would redefine the current process as a "System Process" which allowed some other things to happen (note that // is not a comment in SPL, I just use it here for readability):
code:INTEGER PROCEDURE SETSYSPROC; // declare subroutine
OPTION PRIVILEGED; // requires privileged mode
BEGIN
PROCEDURE ERRORON; OPTION EXTERNAL; // declare external routine
ERRORON; // call external routine
ASSEMBLE (
LDXI 4; // load 4 into index register
PLDA; // load from absolute address (4)
LDI %11; // put %11 (9) on Top Of Stack (TOS)
LADD, STAX; // add top 2 elements on stack and store result in index register
PLDA; // load from absolute address
DUP, NOP; // copy TOS
LDI 4; // put 4 on TOS
DPF 6:3; // deposit TOS value into TOS-1 bits 6:3
PSTA; // store TOS value into absolute addreee
EXF 6:3; // extract bits 6-8 from TOS
STOR Q-4;
); // store result in Q-4 (return value)
END;
code:PROCEDURE RESETSYSPROC(INDEX);
VALUE INDEX; // INDEX is a value type
INTEGER INDEX; // INDEX is an integer
OPTION PRIVILEGED; // YES, this too requires privileged mode
BEGIN
PROCEDURE ERROREXIT(SDEC,ERR,PARM); // declare external routine
VALUE SDEC, ERR, PARM;
INTEGER SDEC, ERR, PARM;
OPTION EXTERNAL;
BEGIN
ASSEMBLE(
LDXI 4; // load 4 into index register
PLDA; // load from absolute address
LDI %11; // push 9 onto stack
LADD, STAX; // add top 2 items on stack, and store result into index register
PLDA; // load from absolute address
LOAD Q-4; // load parameter
DPF 6:3; // deposit parameter into TOS bits 6 - 8
PSTA
); // store TOS into absolute address
ERROREXIT(1,0,0);
END;
After transferring to Ohio State, I learned CLU and LISP.
So, fellow programming Goons, what is the oldest piece of code you still have around?
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Sep 25, 2017 05:57
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