* NPR2 v1.0. 28th September 1990 * ------------------------------ * The Problem * ----------- * PAL Amigas occasionally boot up with an NTSC 200-line screen. * This is rather annoying, as windows won't open to full size, * and some programs won't run. The machine has to be reset - and * there's always the possibility of the problem recurring on * reboot. * The Solution * ------------ * Declan Mc Ardle wrote a neat little program called NoPalReset * which checked the DisplayFlags in GfxBase. If the screen was * NTSC, the machine was reset using the proper Commodore Reset * Code. * The Other Problem * ----------------- * NoPalReset worked fine on most Amigas (including mine) but * users of newer machines (mostly B2000s) reported repeated Guru * Meditations. Some unfortunates even got their hard disks * scrambled.¹ * -------- * ¹: This is purely on hearsay, so I cannot prove it. * No disrespect is implied in any way towards Mr. Mc Ardle. * -------- * This seemed odd, because the source code supplied with * NoPalReset seemed correct. There was one tiny mistake, but * that would probably not cause any problems (and it would only * be executed if your machine was in a *bad* way anyway). * Disassembling the executable image provided a new lead; the * source and the object code didn't match. There were a couple * of subtle nuances which could lead to problems. * Commodore's Reset Code MUST be LONGWORD aligned. It was only * word aligned in NoPalReset, and this could cause problems. * Also a novel (shortcut ? I'm not sure) method was used in * determining the display mode; this probably wouldn't cause any * damage, but is contrary to Official Policy. * The Solution * ------------ * Enter NPR2 (NoPALReset 2). It does everything that NoPalReset * was supposed to do, but strictly by the book. It's been fairly * heavily tested; assuming the Relocator keeps its promise to * relocate to longword boundaries (as it must) the Commodore * Reset Code will be longword aligned. All libraries opened are * closed on exit, so no memory will be lost * Using NPR2 * ---------- * Copy the NPR2 program into the C: directory of your boot disk * - it's only 188 bytes long. Now edit your S:Startup-Sequence, * and insert a line at the start reading * C:NPR2 * Resave your S:Startup-Sequence, and the next time you reboot * NPR2 will make sure you get a PAL screen. * RUNNING NPR2 ON AN NTSC AMIGA IS SINGULARLY POINTLESS and is * therefore not recommended. * When NPR2 reboots the machine, you get the bright white screen * very suddenly. This can be a disconcerting if you're not * expecting it. Therefore it's not clever to install NPR2 on * someone else's machine without telling them, since nervous * users don't appreciate being traumatised. * About the Source * ---------------- * Declan's code was very well commented, so only needed * rearranging and patching to fix it up. It used a lot of * includes for such a small program, so the relevant details * were spliced in to make the source file self-contained. It's * also strictly Metacomco ASSEM compatible now, only because I * don't have DevPac 2. * [Fixing the source wasn't helped by a misprint in a reference * book which said that gb_DisplayFlags is actually one longword * on from where it really is. That got me for a while.] * To rebuild NPR2, just run this file (NPR2.DOC) through your * favourite assembler. It's your assembler's fault (for not * being ASSEM compatible) if any errors crop up. * For Charlie Gibbs' A68k, * A68K NPR2.DOC * and then link (using The Software Distillery's Blink) * Blink NPR2.o * Depending on your assembler's ability to optimise branches, * you should get an executable of around 188 bytes. * Tools used * ---------- * All the software tools used to build NPR2 are freely * distributable, and available in the Fred Fish Collection. * Tool Name Version Author Fish Disk * ----------------------------------------------------------------- * Text Editor DME 1.40 Matt Dillon 359 * Assembler A68K 2.61 Charlie Gibbs 314 * Linker Blink 6.7 The Software Distillery 314 * Monitor Mon 1.24 Timo Rossi 310 * Calculator Calc 3.0 Jimmy Yang 210 * Distribution * ------------ * This work (NPR2.DOC and the NPR2 executable) may be freely * distributed by any means as long as * - no charge is made for the work itself * - NPR2.DOC and the NPR2 executable are not altered * - NPR2 is not documented in any other way apart from a * verbatim NPR2.DOC * You are free to make changes to NPR2.DOC, but you must not * distribute the modified forms under the same name. If any * changes are made to this document, my name and address MUST be * removed too. * No guarantee is given that this software fulfils any specific * task or purpose. Statements made herein which constitute an * infringement of local statutory rights are invalid. * Stewart C. Russell * 140 Capelrig Road * Newton Mearns * Glasgow * SCOTLAND * Length of file NPR2 is 188 bytes. * Length of file NPR2.DOC is 06975 bytes. * And now, for some source code... IDNT NPR2 * NPR2 by Stewart C. Russell, 28th September 1990 * Based on `NoPalReset' by Declan Mc Ardle. * Detects if Amiga is in NTSC or PAL mode, resets if in NTSC mode. SECTION NoPALReset,CODE _AbsExecBase EQU 4 _LVOOpenLibrary EQU -552 _LVOCloseLibrary EQU -414 _LVOSupervisor EQU -30 gb_DisplayFlags EQU 206 ERROR EQU 20 NTSC EQU 1 MOVE.L _AbsExecBase,a6 Put ExecBase in a6. LEA GfxLib,a1 Put Gfx name in a1. MOVE.L #33,d0 Oldest Current Version. JSR _LVOOpenLibrary(a6) Open Graphics Library. MOVE.L d0,_GfxBase Put pointer in _GfxBase. TST.L d0 Was it 0 (Library Unobtainable) ? BEQ quit If so exit, else - MOVE.L _GfxBase,a1 Put _GfxBase in a1. MOVE.W gb_DisplayFlags(a1),d0 Put Display Flags in d0. CMP.W #NTSC,d0 Compare it with NTSC (= 1). BEQ reboot If it's equal, RESET. JSR CloseGfx Close Graphics library. CLR.L d0 Clear d0. (No error code) RTS Go back to CLI. quit: MOVE.L #ERROR,d0 Set d0 to FAIL error code. RTS Go back to CLI. CloseGfx: MOVE.L _GfxBase,a1 Move address in _GfxBase to a1. JSR _LVOCloseLibrary(a6) Close the Graphics Library. RTS * What follows is the official Commodore-Amiga Reset Code. * Accept *no* substitutes. reboot: MOVE.L _AbsExecBase,a6 Get a pointer to ExecBase. LEA.L MagicResetCode(pc),a5 Location of code to Trap to. JSR _LVOSupervisor(a6) Start Code (must use JSR). CNOP 0,4 IMPORTANT: Must be longword aligned. MagicResetCode: LEA.L 2,a0 Point to JMP instruction at start of ROM. RESET All RAM goes away now! JMP (a0) Rely on prefetch to execute this instruction. * Only data and stuff follows. Technically it should go in a hunk of its own, * but that makes the program unnecessarily large. GfxLib: DC.B 'graphics.library',0 CNOP 0,4 _GfxBase: DC.L 0 END