BBS: Inland Empire Archive Date: 02-05-93 (08:51) Number: 362 From: JERRY HUNTER Refer#: NONE To: DIK COATES Recvd: NO Subj: COM4 and COM3 Conf: (2) Quik_Bas
> My BIOS (?) does not premit use of the ports associated > with COM3 and 4, and the port values are zero and zero > for these locations... > Simply swapping port addresses does not work... Cram the base port address (BPA) for the port you want to use into the slot for COM1: or COM2: (Use the port with the correct IRQ, e.g. if you're trying to access COM4:, cram it to COM2's BPA, since the IRQ for COM4 and COM2 share IRQ 3 by default.) A typical method for obtaining this result might be as follows : DEF SEG = &H40 Poke 0,&HE8 Poke 1,&H03 DEF SEG This example (untested, but really pretty hard to screw up) crams 3E8 (the semi-standard BPA for COM3:) into the slot for COM1. (Grin - the ONLY way I could have screwed it up is to have flipped the high- and low-order bytes.... use DEBUG<CR> d 0040:0<CR> to view the BIOS data area to verify that they're falling into place as . E8 03 F8 02 E8 03 E8 02 This _should_ work (off the top of my head, but I've been forced to use it enough times that I should be able to sleepwalk thru it)... that is, unless I'm accused of blatant OPPORTUNISM or something (giggle)... Hope it helps, J.Hunter --- GEcho 1.00/beta * Origin: DarkStar - QB45 Comes ALIVE! - (501) 631-5976 (1:391/2090)
Books at Amazon:
Back to BASIC: The History, Corruption, and Future of the Language
Hackers: Heroes of the Computer Revolution (including Tiny BASIC)
Go to: The Story of the Math Majors, Bridge Players, Engineers, Chess Wizards, Scientists and Iconoclasts who were the Hero Programmers of the Software Revolution
The Advent of the Algorithm: The Idea that Rules the World
Moths in the Machine: The Power and Perils of Programming
Mastering Visual Basic .NET