MA18@SYSE.SALFORD.AC.UK (05/07/88)
Subject: UNARC revisited My thanks were slightly premature! ON my return home I have discovered that my eyesight is not failing, nor is my brain, and UNARC will not extract! A good dose of Z8E has solved the problem, but not explained it. UNARC is sensitive to the value of location 3E. If that is zero (it is on my machines) then the help info and the action of the program is adjusted to stop file extraction! UNARC will now work OK if I precede it (in an alias) by a swift poke of this location. NOW - why is UNARC checking this location? My CP/M documentation says 'NOt currently used, reserved'. Is this another form of 'wheel' byte used by BYE or some such program? -- Tony Addyman
raf@cup.portal.com (05/10/88)
Tony Addyman (MA18@SYSE.SALFORD.AC.UK) writes about the inability to extract from archive files using a wheel-byte protected version of the UNARC program. This is a classic example of what happens when programs are distributed in a form other than that recommended by the author. Apparently, Tony is using a version of UNARC which has been modified for use on remote BBS systems (RCP/M's). Let me assure Tony that (1) UNARC has the capability to extract, as well list and typeout, archive files (that is the the primary reason for the program's existence), and (2) the authorized distribution of UNARC.COM will work on virtually any standard CP/M system without alteration (or sensitivity to location 3E). The latest (and only such) "authorized" distribution, version 1.6, is contained within a file named UNARC16.ARK. This is a "self-extracting" archive. If no earlier version of UNARC is available, this file can be renamed to UNARC16.COM and then executed on the user's system. This will generate working program versions for both Z80 systems (UNARC.COM) and 8080 systems (UNARCA.COM), along with program documentation (UNARC.DOC) and all associated files. In particular, an assembly language overlay file (UNARCOVL.ASM) is provided for purposes of local modifications to UNARC for non-universal options (such as wheel-byte protection used on RCP/M systems). That file contains an explicit warning to not redistribute modified versions of the program. This warning was apparently ignored by whoever supplied Tony with his copy of the UNARC program. Bob Freed Internet: Robert_A_Freed@cup.portal.com Newton Centre, MA UUCP: ...!sun!portal!cup!Robert_A_Freed