PET In Transition

Jim Butterfield, Toronto

A transition issue of the PET GAZETTE is very appropriate, because the PET itself is in transition. New products and new software are going to change the nature of the machine. Old hands at PET system use will have to learn new tricks.

A lot of "old" software won't work on the new machines. Those chess and music playing programs, for example, can't make the transition in their present form. Many of the POKEs and PEEKs have shifted to new locations. SYS, USR and WAIT commands will need reworking.

The machines themselves have a few hardware changes. A new memory arrangement eliminates screen hash. The screen can no longer be blanked, so that certain special effects (explosions, etc.) are difficult to achieve. The character generator has changed, giving an unfamiliar reversal of upper and lower case. The memory expansion edge connector is physically different; it appears as if Commodore doesn't intend it to be user accessible any more. Instead, a "mother board" architecture is hinted at; and empty ROM sockets suggest that new software may be forthcoming. An assembler? New languages? It's anybody's guess right now.

Further hardware changes are rumoured. Most of the ones I hear are associated with screen format changes (80 characters? Colour? Programmable characters?)

With all these changes, what should the PET owner do? Stay with his original machine? Retrofit with the new ROM chips? Buy the new model?

My recommendation is this: upgrade with new ROMs, or buy a new unit; but either way, take the plunge. You'll want the new model if you are strong on large keyboards, green screens, and/or ROM expansion capability; otherwise, stay with your existing machines but fit the new ROM programs.

There's too much good stuff in the new software to hold back. The limit on array size is lifted; tape files behave correctly; the IEEE-488 bus works better; the built-in Machine Language Monitor is very valuable; you can now pull the computer out of a total crash without losing memory; and numerous little improvements have been made.

Commodore may introduce more ROM's in the future. But I believe that they won't tinker with lower memory (locations 0 to 1023 decimal) to any great extent. So an upgrade which is made now should last for a while.

Commercial software houses will have to wrestle with the upgrade, of course. Buyers will have to closely examine programs on sale to make sure that they are compatible with their computer model. "AC/DC" programs, which will run on any existing ROM, will be a help (I understand that such a version of Microchess will soon be available). Eventually, I believe that the upgraded ROMs will become standard, and most software will be written for them; the original ROM will fade out of the picture.

Clubs, and newsletters like The PET GAZETTE, will also need to cope with this transition. Programs and techniques will have to be carefully identified: which ROM set will they work on? Where possible, two versions will be desirable.

Eventually — hopefully — we'll all settle back into a standard machine. And then we can focus our attention fully on the main objective: making it do the jobs we want to do.

Memory locations for ROM upgrade on PET computers

Jim Butterfield, Toronto