Scor­pio News


January–March 1987 – Volume 1. Issue 1.

Page 53 of 63

feature is extremely useful even on a two floppy system, but is invaluable in systems with Virtual or Winchester dives. (If the default USER is changed by the DFU command, the new default USER will be searched instead of USER 0 in the above example.

NOTE that CCPZ has been standard with all Gemini CP/Ms for some time now.

Improving the CCP – ZCPR3

A second method of CCP improvement is possible by the use of the more recent versions of ZCPR. In addition to replacing the CCP, additional memory is used above CP/M and a considerable system enhancement is obtained. App. 2 Ref. 10 describes the system more fully. I am hoping to try ZCPR3 in the near future, but I have not used it yet so I can only indicate a few of the features :–

Environment Descriptor – Holds information on the ZCPR3 system.
Named Directories – Allows Drives and USER areas to be named.
Commands –
Resident Command CCP – GO, SAVE, GET, JUMP.

Flow control – Allows conditional testing of CCP processing.
Input/​Output Package – Routes I/O and redirects data
Terminal Descriptor – Describe the Terminal and its commands.
Five level search PATH. (Easily redefinable)
Wheel Byte – Improves system security.
Drive and USER access via C6: type command. Support is provided for security via Passwords.
Large number of support utilities like HELP, MENU, SHOW, UNERASE, CONFIG, CLEANDIR etc;

One penalty of ZCPR3 is that some additional system memory is needed which reduces the available TPA by about 4k. If this were a problem with certain programs, a more standard operating system could be loaded with such programs.

Improving the BDOS – BDOSZ

This area of CP/M is the last amenable to modification. However a BDOS replacement known a BDOSZ is available, and improvements have been incorporated by using Z80 code to provide extra room for refinements in the 3.5k of space available. BDOSZ provides the user with much better recovery from errors than the standard BDOS. A summary of features that are provided by BDOSZ :–

  1. When a ‘SELECT ERROR’ occurs you may enter a valid drive No. and continue.
  2. When a Disk is ‘R/O” you will be asked ‘DO IT ANYWAY’. If you answer ‘>%rsquo; BDOSZ will reset the disk and proceed.
  3. If a ‘R/O’ file is found during ERA, the screen will display the file name and the sane query will be printed. If you answer ‘Y’ the file R/O flag will be reset, and the ERA carried out. This applies to REN and SAVE activities as well.
  4. If a bad sector is found, a ‘READ’ of ‘WRITE’ error message will be displayed. ^C will cause a Warm Boot, but any other key will cause the error to be ignored, so that it is possible to recover partly bad files.
  5. DISK or DIRECTORY FULL errors. BDOSZ will display a ‘Change Disk Y/N/^C’ option and allows the Disk to be changed if desired.

BDOSZ is a worthwhile improvement to CP/M. (N.B. I have found a Bug – see note in App 1.)

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