Turbo Pascal was written by Borland way back when I first started programming. I played a game back then called Trade Wars 2002 and I recently rediscovered it. I read some forums about how certain days seem to be "better" for trading than others and it smacked of a crappy random number generator.
I disassembled a program written in Turbo Pascal and here is the assembly for the random functions:
; Randomize(void)@Randomize$qv proc farmov ah, 2Chint 21h ; DOS - GET CURRENT TIME; Return: CH = hours, CL = minutes, DH = seconds; DL = hundredths of secondsmov word ptr RandSeed, cxmov word ptr RandSeed+2, dxretf@Randomize$qv endp; Random(Word)@Random$q4Word proc farcall permuteSeedmov bx, spmov cx, dxmul word ptr ss:[bx+4]mov ax, cxmov cx, dxmul word ptr ss:[bx+4]add ax, cxadc dx, 0mov ax, dxretf 2@Random$q4Word endp; PermuteSeed(void)PermuteSeed proc nearmov ax, word ptr RandSeed; uint16_t seedHi = RandSeed1;mov bx, word ptr RandSeed+2; uint16_t seedLo = RandSeed2mov cx, ax; uint16_t tmp = seedHi;mul cs:word_1DA26 ; dw 8405h; uint32_t result = seedHi * 0x8405;; uint16_t seedHi = (result >> 16) & 0xFF;; uint16_t resultLo = result & 0xFF;shl cx, 1shl cx, 1shl cx, 1; tmp <<= 3;add ch, cl; tmp |= (tmp << 16) & 0xFF00;add dx, cx; resultLo += tmp;add dx, bx; resultLo += seedLo;shl bx, 1shl bx, 1; seedLo <<= 2;add dx, bx; resultLo += seedLo;add dh, bl; resultLo += (seedLo & 0xFF) << 16;mov cl, 5; tmp = (tmp & 0xFF00) | 0x05;shl bx, cl; seedLo <<= 5;add dh, bl; resultLo += (seedLo & 0xFF) << 16;add ax, 1; seedHi++;adc dx, 0;mov word ptr RandSeed, axmov word ptr RandSeed+2, dxretnpermuteSeed endp