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Path: utzoo!watmath!clyde!cbatt!ihnp4!alberta!calgary!ingoldsby
From: ingoldsby@calgary.UUCP
Newsgroups: comp.sys.m6809
Subject: Re: Multipak Upgrades
Message-ID: <724@vaxb.calgary.UUCP>
Date: Tue, 9-Dec-86 15:41:37 EST
Article-I.D.: vaxb.724
Posted: Tue Dec  9 15:41:37 1986
Date-Received: Sun, 14-Dec-86 00:03:58 EST
References: <1431@lsuc.UUCP>
Distribution: na
Organization: U. of Calgary, Calgary, Ab.
Lines: 44
Summary: Upgrading CoCo disk controller

In article <1431@lsuc.UUCP>, jimomura@lsuc.UUCP (Jim Omura) writes:
> 
> I can't use my disk controller at all (it is the original Shack
> controller which requires the 12 volt line) nor can I use the disk

I'm in a similar situation.  I have the old (needs 12v) disk controller
and I plan on using it with my CoCo 3.  I built Multipak like box
shortly before Radio Shack came out with the real Multipak, and have
been using it ever since.  My interface box has its own 5v supply
that tracks the computer's 5 volt supply, but since the interface didn't
need much 12 volts, I just used (and passed through to the program Paks)
the computer's +/- 12 volts.  My options are:

       1) Open the CoCo 3 and put 12 volt supplies inside it.
          I wouldn't have to touch the custom interface, but
          would void the warranty on the Coco III.

       2) I could put a 12 volt supply in the box that would
          always (even when the 5 volt supply was off) send
          12 volts to the program paks and disk controller.
          Some chips dislike having one power supply voltage
          on and others off.  I can find no reference to any
          such problems in the WD1793 spec sheets.  Does anyone
          know whether the WD1793 would dislike this situation?

       3) I could make a 12 volt supply for the interface box
          that turned on with the computer's 5 volt supply.  This
          is a little more complicated than 2.  Also, some devices
          require specific power up/power down sequences for the
          different supply voltages.  Does anyone know if the
          WD1793 (and other common program pak chips) care?
          (This is really the same question as 2).

Also, is there any problem using the Ver 1.1 Disk Basic Roms with
the new CoCo III?  I presume I won't have the DOS command, but I
could probably live without it.  Will Ver 1.2 (or whatever's newest)
plug into the ROM sockets, or do the new controllers use different
ROMs?

Any comments appreciated.

                                 Terry Ingoldsby

...ihnp4!alberta!calgary!ingoldsby