Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!lavaca.uh.edu!uhnix1!sugar!splut!jay From: jay@splut.conmicro.com (Jay "you ignorant splut!" Maynard) Newsgroups: comp.os.cpm Subject: Re: MOVCPM has copy protection Summary: Not intended as copy protection... Message-ID: Date: 12 Feb 90 23:59:59 GMT References: <1534@shell.shell.com> <9719@spool.cs.wisc.edu> Reply-To: jay@splut.conmicro.com (Jay "you ignorant splut!" Maynard) Distribution: usa Organization: Confederate Microsystems, League City, TX Lines: 35 In article <9719@spool.cs.wisc.edu> tonyrich@titanic.cs.wisc.edu (Anthony Rich) writes: >According to the book "Inside CP/M" by David E. Cortesi, MOVCPM has a kind >of copy protection built into it. When it starts up, it does some >checking to see whether the copy of CP/M you're trying to generate with >MOVCPM matches the copy of CP/M you're currently running. If not, it >displays the message "Synchronization error" and quits. (I'm not sure >what it actually tries to match. I think it does some kind of checksum.) >As a result, you can't run MOVCPM to generate a new copy of your CP/M >while running someone else's copy of CP/M. This is not intended as copy protection; it's intended to prevent MOVCPM from building a garbage CP/M image. MOVCPM uses a bitmap to determine which bytes to relocate when moving the CP/M image. This includes the BIOS area as well as the BDOS and CCP. The original intent was that you'd MOVCPM 54 (or whatever...it's been a looo-o-o---oong time :-), then SYSGEN the resulting image, and then boot. Each licensed CP/M distributor had utilities that built the MOVCPM program from his customized image. For those of us who had to install our own BIOSes, you had to MOVCPM, then load the BIOS on top of that, then SYSGEN and boot. The "Synchronization error" message is produced when the resulting image, because of a difference between the systems, would have the wrong bytes relocated, and therefore would be garbaged. Nobody had even *thought* of copy protection when MOVCPM was developed... -- Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can jay@splut.conmicro.com (eieio)| adequately be explained by stupidity. {attctc,bellcore}!texbell!splut!jay +---------------------------------------- Free the DC-10!