Re: What type of HD can I use with my ][+

[dempson@actrix.gen.nz (David Empson)]

Vince Briel <vbriel@telocity.com> wrote:

> I have my original ][+ that I've had for 20years now.  I never had a hard
> drive for it, but it would be nice to be able to back up some of my disks.
> Can I use a focus hard drive?  The specs I've read about say for the ][e
> or ][gs?

I don't know whether the Focus would work, but you would be able to use
the original Apple SCSI Card (but _not_ the High Speed, one, which
requires an enhanced IIe or later machine).  There are also some much
older hard drives and controller cards (like the Sider) which would work
on the II+.

Apple's 5 MB or 10 MB ProFile would work, but I'd hesitate to recommend
it, since it is very difficult to do a low level format (you need an
Apple /// with the right hardware and software, and special firmware to
install into the drive).

> Also, can you use DOS 3.3 or do you have to use prodos?

All "recent" hard drive interfaces (including all SCSI cards, the Focus
and even the ProFile) only support ProDOS (and Apple II Pascal 1.3,
which can use the ProDOS driver on the card).

Older hard drive interface cards which were designed for the II+ (like
the Sider) generally have support for DOS 3.3, and if they are old
enough, they won't support ProDOS at all.  I think the Sider was able to
partition the drive into regions for use by DOS 3.3, ProDOS, Pascal and
CP/M.

It is difficult to use DOS 3.3 on a hard drive, because the file system
was only designed to allow a volume size up to 400 KB, with no support
for subdirectories, so you can't organise the files on the volume (other
than physically rearranging the order of directory entries, and using
tricks like fake files as headers).

The hard drive interface cards with special support for DOS 3.3 usually
work by making use of the "volume" mechanism to logically divide a
larger hard drive into multiple volumes, each of which is either 140 KB
(the same size as a 5.25" disk) or 400 KB (the maximum size supported by
DOS 3.3).

To switch volumes, you use the 'V' parameter in a DOS command, e.g.

CATALOG,V1
CATALOG,V2

etc.

There are a maximum of 253 volume numbers available, so with 140 KB
logical volumes, you have a maximum of 34.5 MB (35420 KB) which can be
accessed on a single physical drive.  With 400 KB logical volumes, the
limit is 98.8 MB (101200 KB).

Another complication of using DOS 3.3 with a hard drive is that the
operating system has to be patched to work with anything apart from a
5.25" floppy drive.  These patches usually work by disabling some
standard part of DOS 3.3, e.g. the ability to format a floppy disk.


With ProDOS, the maximum volume size is 32 MB, and it supports
subdirectories, which makes file organisation much easier on large
volumes.

If you have a hard drive which is larger than 32 MB, SCSI cards allow
you to partition the drive, given the right software.  You can easily
access two partitions (as drive 1 and drive 2), but exceeding this limit
is a little tricky.

If you are running ProDOS-8 1.2 or later and the SCSI card is in slot 5,
and you don't have a disk controller card (or something which looks like
one) in slot 2, then ProDOS can provide access to a third and fourth
partition, which are logically remapped as S2,D1 and S2,D2.  (This
feature must be supported by the SCSI card - it is supported by Apple's
one, but might not be by some third-party cards.)

ProDOS-8 1.9 is the last version which works on the II+, unless you
replace the CPU with something which is compatible with the 65C02 (and
most standard 65C02 processors won't work in the II+).

With ProDOS-8 2.0 or later, ProDOS supports remapping extra drives into
all slots which don't have disk controller cards, so you have a
theoretical limit as high as 12 partitions, depending on the SCSI card
and what is in your other slots.  The original Apple SCSI card only
supports 7 partitions in total.

Another one worth noting is the RamFast SCSI card.  I don't know whether
it would work on a II+, but it supports manual assignment of extra
partitions to any unused slot/drive, and can do this with any ProDOS
version.

-- 
David Empson
dempson@actrix.gen.nz