Dear John, Since I'm buried under work at the moment, I'm forwarding your question to the cbm-hackers mailing list. (Note: when replying to the message, be sure to send a CC to John.) I have never required the UI- or UI+ commands, but your situation could be different, since the PAL VIC-20 runs at 1.108 MHz while the NTSC VIC-20 runs at 1.023 MHz. The PAL C64 is much more slower than the PAL VIC-20: 0.985 MHz minus the cycles stolen by the VIC-II. The NTSC C64 runs at 1.023 MHz. The drive runs at 1 MHz in any case. I'd rather suspect some kind of a hardware problem. The UI-/UI+ setting is definitely not written on the disk; it just alters some delays in the drive's serial bus protocol. Marko ---------- Forwarded message ---------- Date: Tue, 14 Nov 2000 13:40:59 -0800 From: "Kotrba, John" <KOTRBJO@mail.northgrum.com> To: "'Marko.Makela@HUT.FI'" <Marko.Makela@HUT.FI> Cc: 'home' <email@example.com> Subject: CBM 1541 Marko; I see you have considerable interest in details of old CBM equipment. Maybe you can advise me since I see you provided a disassembly of 1541 ROM. I am using a 1541 drive with my VIC-20, operating BASIC and FORTH (Datatronic v1.1). The owner's guide for 1541 refers to "matching drive to computer" by sending "UI-" to control channel if VIC and "UI+" if C64 computer. I have found I need to do this reading BASIC program files, else drive spins without finding program. When I use FORTH (ramdom file format), it seems that it I forget to send command "UI-" command, my disc reads fine (written previously on same drive). Now I may have used that command possibly when I first wrote to that disc, but not now. However, I'm making a new system disc and having trouble getting it to write to a newly formatted disc. Now I'm wondering it this is because I got used to not sending the UI- and this is how its showing up. I guess my question is: should that command be manditory anytime disc is used, or is it possible its needed when first creating disc and then accomodates even if not sent? Also, might the nature of file system eg sequential program vs ramdom blocks matter. I eventually find answers to these type of questions experimentally, but its a big waste of time. I'm currently trying to create several FORTH system discs for backup purposes so I don't have an accident and loose much effort. I can only devote so much time to a hobby! Your opinion? John Kotrba - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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