Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!rutgers!cbmvax!fred From: fred@cbmvax.UUCP (Fred Bowen) Newsgroups: comp.sys.cbm Subject: Re: trouble with 128 running in 64 mode Message-ID: <2315@cbmvax.UUCP> Date: Fri, 11-Sep-87 15:28:52 EDT Article-I.D.: cbmvax.2315 Posted: Fri Sep 11 15:28:52 1987 Date-Received: Sat, 12-Sep-87 19:41:37 EDT References: <3495@rutgers.rutgers.edu> <1662@ulowell.cs.ulowell.edu> Organization: Commodore Technology, West Chester, PA Lines: 37 In article <1662@ulowell.cs.ulowell.edu>, sbrunnoc@hawk.CS.ULowell.Edu writes: > The 1571 is NOT 100% compatible with the 1541 even when it is in > 1541 mode. This has been documented in RUN magazine. I believe that > Activision programs written for the C64 cannot be loaded on the 1571. It is DOS command compatible, of course, but some copy-protect schemes are not compatible. Some changes to the ROM (extending the data density tables, for example, to cover tracks >35) and the hardware (data separator) were actually done to *improve* reliability for many programs (GEOS, etc.). Unfortunately not everything was improved by this. Please note that "extra tracks" are "out of spec" to begin with- kinda like using un-implemented opcodes, really. Also, while 1541's can seemingly improve load reliablility by adjusting the motor spindle speed via a pot, the 1571's do not have this adjustment (another improvement- no belt). The best you can do send the 1571 a 'go 1541 mode' command of the form OPEN 1,8,15,"U0>M0": CLOSE 1. Also, some protect schemes actually diddle with the 6510 port- if you are using a C128, enter 64 mode by holding down the C= key at powerup or reset AND put the CAP LOCK key DOWN. That makes things as C64-like as possible. Finally, some mods made to the 6526 CIA changed timing ever so slightly, adversely affecting some copy-protect schemes (such as Digital Solution's stuff). In just about every case, you see, it is the copy-protection stuff that falls outside our specs that cause the real problem. -- -- Fred Bowen uucp: {ihnp4|rutgers|caip}!cbmvax!fred arpa: beats me tele: 215 431-9100 Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380