Scor­pio News

needed, to a full Z3 system and fancy BIOS, for maximum flexibility, but with the loss of say 6k of T.P.A.

Both Z2 and Z3 are supplied with full source code for all of the software which includes some sixty or seventy utilities that are able to use the special features of their related Z system. It also includes SYSLIB which is a large library of subroutines that are used in the construction of the Z utilities, and may also be used in any other software that the user chooses. The user is thus supplied with all of the information needed to do whatever he likes.

Z3 is upward compatible with Z2, and so comments from here on will generally relate to Z3. The three memory extensions above CP/M with Z2 are the same as with Z3. There is one major difference which concerns the named directory facility. The Named Directory segment of Z2 is 200H bytes long, whereas that with Z3 is only 100M bytes long, (but could be made larger), and deals with 14 names. In practice this seems adequate. Also Z2 itself is not able to use or recognize the names, whereas the Z2 utilities can. This seemed to me to be a major deficiency of Z2, on a Winchester based system. On a Floppy based system, where the media is continually changing, names are perhaps of limited use. especially on systems where the disks are under say 500k. (Although the system allows the directory segment to be easily changed, and so a new one could be loaded for each application.)

Fig 1 – ZCPR2 and ZCPR3 Memory Maps – Typical