kws1x@dale.acc.Virginia.EDU (Kenneth W. Smith Jr) (04/14/89)
Yet another problem has arisen to be presented to the CBM-Sages of Netland...(praise, praise...) (First an aside: Thanx to all those who sent me info regarding the Koala screen problem. It works, it works! ;) ) While using the C= Assembler System, you know the one, I used the slash symbol to attempt to load a program from my 1581. (This system allows you to load using "/filename".) Anyway, the drive errored out. Reading the error channel gave me error#23, a supposed checksum problem. Dummy-me didn't have a backup of the disk I was accessing, and the same error pops up for half of the programs on the disk. (I need these programs!!!) After searching through various books, I could find nothing to get me on the right track. The only track/sector reading program I have is unfortunately one of the erroring programs. (The only one for the 1581, that is). My problem is how can I reclaim those programs. Mucking about with disk headers and sectors is a relatively new frontier for me, and I fear mangling the program files any further. Any advice and/or book references for help would be GREATLY appreciated!! Thanx in advance, K W Smith, Jr. +--------------------------------------------------------+ | "But it's only a toilet seat!" | | "Oh, no. It is much more. It is a means | | to summon us!" | | -Quotes from Clive Barker's little | | known film: "LIDRAISER" | +--------------------------------------------------------+
brendan@jolnet.ORPK.IL.US (Brendan Kehoe) (04/15/89)
In article <441@galen.acc.virginia.edu> kws1x@dale.acc.Virginia.EDU (Kenneth W. Smith Jr) writes: > My problem is how can I reclaim those programs. Mucking about >with disk headers and sectors is a relatively new frontier for me, and I >fear mangling the program files any further. Any advice and/or book >references for help would be GREATLY appreciated!! Get a copy of "Inside Commodore DOS" by Dick Immers & Gerald Neufeld..on page 469 of it, there is a program called "Recover Track & Sector"..you may have to change lines 420 and 530, due to possible differences in the zero page of the 1581 as compared to the '41 (yoo hoo Commodore...$71 and $8 = what on the 81?)..a few other changes (like 140-150, where it decides the track # and max sectors) may also have to be done..or you could even just rip the routines that read then re-write the sector out and write a lil prg of your own. While we're at it, does anyone know where to get aa half-decent memory map of the 1581? -- Brendan Kehoe brendan@cup.portal.com | GEnie: B.KEHOE | Oh no! I forgot to say goodbye brendan@chinet.chi.il.us | CI$: 71750,2501 | to my mind! brendan@jolnet.orpk.il.us | Galaxy: Brendan | - Abby Normal
fred@cbmvax.UUCP (Fred Bowen) (04/18/89)
In article 441@galen.acc.virginia.edu> kws1x@dale.acc.Virginia.EDU writes: > While using the C= Assembler System, you know the one, I used the >slash symbol to attempt to load a program from my 1581. (This system allows >you to load using "/filename".) Anyway, the drive errored out. Reading the >error channel gave me error#23, a supposed checksum problem. Dummy-me >didn't have a backup of the disk I was accessing, and the same error pops >up for half of the programs on the disk. (I need these programs!!!) This problem is fairly common to some (by no means all) 1581's. Like the SAVE-@ problems of earlier drives, the cause has proven elusive and it's not certain that it's a software problem. Miklos Garamszeghy wrote about this in an article in Twin Cities 128 (issue #21), and included a program called '1581 Fix Track' which attempts to recover from these CRC errors. I know the program is available on QLink and GEnie, and probably elsewhere. The program takes advantage of the data in the track cache, writing it back to disk. This will eliminate the error, but cannot guarantee the validity of the data. I will see if Miklos has any objection to uploading the small BASIC program here (the program is (C) Herne Data System, LTD.). You should also check that your drive contains a WD1772 controller (not a WD1770). The replacement is still free I believe. I posted a program to report the controller type here not too long ago. In article <487@jolnet.ORPK.IL.US> brendan@jolnet.ORPK.IL.US writes: > Get a copy of "Inside Commodore DOS" by Dick Immers & Gerald Neufeld..on > page 469 of it, there is a program called "Recover Track & Sector"..you may > have to change lines 420 and 530, due to possible differences in the zero > page of the 1581 as compared to the '41 [...] Methods other than Miklos' to recover the data by reading/writing the sector given in the error message will often not work because the error could be anywhere in the track and not necessarily at the specific sector indicated. Also be careful using recovery programs written for other drives- the 1581 does not use GCR encoding, and the memory map is quite different! -- -- Fred Bowen uucp: {uunet|rutgers|pyramid}!cbmvax!fred arpa: cbmvax!fred@uunet.uu.net tele: 215 431-9100 Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380