Re: Apple II ROMs?

["RedskullDC" <RDC@oz.org>]

Hi Ernest,

"Ernest" <leucoplast@seanet.NOSPAM.com> wrote in message
news:mScQb.3561$U%5.19794@attbi_s03...

> The original Apple II was sold with three ROMs (Monitor, and Integer
Basic,)
> but no Applesoft or Autostart ROMs. Later, you could purchase those ROMs
to
> make your Apple II be II+ compatible (applesoft, autostart, etc.) Is that
> correct?

6 x 2k ROMS actually. Very similar to 2716 EPROMS, but the polarity
of the CHIP SELECT lines differ. Your board would have to be modified to
accept
2716 eproms.

>
> If I have an early clone motherboard which only has three ROMs, is it
> reasonably safe to assume that it was built as an Apple II clone, rather
> than a II+ clone?

Most, if not all clones appeared after the arrival of the Autostart monitor.
I have seen a few clone ROM cards fitted with Integer basic.
Reasonably safe to assume it is a II+ clone.

>
> For example, if I have a clone board that is laid out like an Apple II
> board, and it has the six ROM sockets but only three are being used
> (D0,E0,F0,) I would assume that that system is meant to be a clone of the
> II+, and that the owner would provide his own D8,E8,F8 ROMs. Correct?

If the chips are 2716 types, then you are missing three of the roms. If they
are 2732 types, then that is all that you need.
>
> But... if I have a clone board that only has the initial three ROMs, and
no
> room for expansion, should I assume that it's meant to be a clone of the
> original Apple II? I guess that they could have used larger capacity ROMs
> which would hold more information but I'm not sure? If they used 32k ROMs
> instead of 16k ROMs, could they have the Autostart and Applesoft code
> included into those ROMs (D0,E0,F0?) Would that work, as far as addressing
> is concerned?

Yes. Have them as 2 x 8k logical spaces with a switch on the high address
lines.
Was a common thing to do when you were using hacked monitor roms to more
easily crack protected disks.
>
> I have one late model clone board that only has the Monitor ROM on the
> motherboard, and two additional ROMs on an expansion card. The card ROMs
> are different sized -one 16k and one 32k. The card has room for two
> additional ROMs but they were never added. However, the system Autostarts
> from a disk drive, and it loads Applesoft on startup (with no disk in the
> drive.) I don't understand how they were able to do so much with those two
> ROMs?


If you are electronically minded, check to see if the the motherboard's /INH
signal is grounded by the insertion of the ROM card, effectively overlaying
the motherboard ROM space.

Is this a BASE64 by any chance?

The BASE64 (and a few other clones) had a function key, that in combinatuion
with the other keys on the keyboard, produced all of the normal FP BASIC
commands from the single key-press.

Since there is no room in the monitor to store the routine to do that, it
employed
a 2732 ROM whose high address line was attached to a soft-switch in the
$Cxxx
space somewhere. (Much like a 32k Apple2C which uses $C028)
The code in the keyboard read routine in the monitor would bring in the
other 2k
bank which housed the extra code, then switch it back out before it exited.

Neat way of expanding some of the monitor routines, or add the mini-assem to
Autostart for example.


>
> I have a Basis 108 that uses six 32k ROMs. Each ROM is somehow divided
into
> two halves. By using a switch before startup, the system can be set to use
> either Basis Basic or Applesoft. In otherwords, each of the six ROMs
> contains code for both versions of Basic. Could the six Basis Basic ROMs
be
> compressed into three 32k ROMs instead of six 16k ROMs? Or does the
> computer look for different parts of the software at different address
> locations?

Previous case is true with the Basis.
>
> If a board does not have an Autostart ROM (or expansion room for one) can
> you use work around that problem by using a ROM expansion card, like those
> old six ROM cards that I've seen on ebay?

Yes, or just burn a new set of Eproms containing the Autostart ROM for your
clone.

Red