APPLICATIONSDIVERS ★ DOS USER DOS OR DOS USER DON'T USE ROMDOS? ★

Art Studio Loader for ROMDOS mk 2Applications Divers
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OK. So you've got the Art Studio running with ROMDOS and you're enjoying the vast storage capacity of a ROMDOS format disk. “Yes, but when I catalogue the disk from the Art Studio it doesn't show all the screen files that I've saved!", I hear someone say. (Not me. Did you say anything, Adam? - Ed)

“Limited buffer size”, I reply, “What you need is a good dose of... User Area Relocation".

So let's get serious. When you select < Catalogue disc > from one of the Art Studio's Filing Menus, the relevant filenames, from the disk in the currently selected drive, are stored in an area of memory set aside for the purpose. Each filename is given a drive prefix (A: or B:) to aid identification. Catalogue a disk in the other drive and the new filenames will be added to those already in store.

With 178K capacity disks, this buffer is more than adequate, but add a 792K capacity disk (something which was not expected when the program was written) and it's quite possible to fill the buffer, and more besides. At best this will result in some files "disappearing" or at worst, cause a very nasty crash.

To avoid this potential disaster, we need to make use of USER AREAS. Not a popular subject, I know, probably due to the fact that they seem totally unnecessary when dealing with 178K capacity disks. But, with a possible 256 files on a D20 format (792K) disk, splitting the directory into manageable chunks makes a lot of sense. The problem is that the Art Studio does not have the facility to change from one User Area to another. Until now...

A little investigative work with a Multiface reveals that the Art Studio makes use of the firmware routine KM_READ_KEY (at &BB1B) to interrogate the keyboard when < Enter Filename > is selected from the Filing Menus. If we can intercept this routine then we can use it to enter a User Number instead of a filename, provided a “special" key is pressed first. And that is exactly what the poke below does. Use it to load the Art Studio instead of STUDIO.BAS and you will be able to select User Areas 0 to 9 as follows:-

  1. Select < Enter Filename > from the Filing Menus.
  2. Press the COPY key. (You will hear a beep)
  3. Enter a User Number. (Use the numeric keys)

All filing operations will use the selected User Area for both drives. Unfortunately the Art Studio does not display the currently selected User Area so it is up to you to exercise due care and attention when loading and saving files.
Next month we'll see how this poke works in greater detail by having a look at the source code listing. And finally, a word of apology to all those of you who typed in the previous loader but it was only after I had written it that the idea for this new loader occured to me.

By Jess Harpur, Campursoft & WACCI

(Note, Jess is the UR in campURsft, Peter Campbell is the CAMP from CAMPursoft. If you're wondering where the soft comes from, that's easy as well, it's from all the ZX81 owners, they're all a bit soft.)

★ EDITEUR: AMSTRAD ACTION
★ YEAR: 1992
★ LANGUAGE:
★ LICENCE: LISTING
★ AUTEUR: Jess Harpur

★ AMSTRAD CPC ★ DOWNLOAD ★

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» Art  Studio  Loader  for  ROMDOS  mk2DATE: 2016-06-07
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★ AMSTRAD CPC ★ A voir aussi sur CPCrulez , les sujets suivants pourront vous intéresser...

Lien(s):
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» Coding Src's » Des illustrations musicales
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» Coding Src's » Duo de Mozart

QUE DIT LA LOI FRANÇAISE:

L'alinéa 8 de l'article L122-5 du Code de la propriété intellectuelle explique que « Lorsque l'œuvre a été divulguée, l'auteur ne peut interdire la reproduction d'une œuvre et sa représentation effectuées à des fins de conservation ou destinées à préserver les conditions de sa consultation à des fins de recherche ou détudes privées par des particuliers, dans les locaux de l'établissement et sur des terminaux dédiés par des bibliothèques accessibles au public, par des musées ou par des services d'archives, sous réserve que ceux-ci ne recherchent aucun avantage économique ou commercial ». Pas de problème donc pour nous!

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L'Amstrad CPC est une machine 8 bits à base d'un Z80 à 4MHz. Le premier de la gamme fut le CPC 464 en 1984, équipé d'un lecteur de cassettes intégré il se plaçait en concurrent  du Commodore C64 beaucoup plus compliqué à utiliser et plus cher. Ce fut un réel succès et sorti cette même années le CPC 664 équipé d'un lecteur de disquettes trois pouces intégré. Sa vie fut de courte durée puisqu'en 1985 il fut remplacé par le CPC 6128 qui était plus compact, plus soigné et surtout qui avait 128Ko de RAM au lieu de 64Ko.