27 May
1997
27 May
'97
11:25 a.m.
My best guess is that maybe you have a 13-sector (DOS
3.2) disk
controller and one 13-sector disk (the one that works), and the
rest of your disks are 16-sector so the 13-sector controller
doesn't know what to do with them. Unfortunately I can't remember
where to peek to find out the DOS or controller version number,
so I don't know how you could verify this.
I seem to remember that if you pull the disk controller card, the 13
sector PROMs say 'P5' and 'P6' on them, while the 16 sector ones are
'P5A'
and 'P6A'.
The other alternative is that if your Apple II+ has less than 48k
of memory, the other disks may be expecting a 48k system and loading
DOS into a part of memory that doesn't exist on your computer. The
I can't remember where to peek to find the top of memory, but anyway, it's
easier to flip the lid and see what RAM chips are fitted. Early Apple ]['s
can take either 4K DRAMs or 16K ones (4116's), with little jumper modules
that are used to strap the signals appropriately. Later apples only take
16K DRAMs.
The RAM chips are inside the while rectangle on the motherboard. There are
3 rows of 8 chips. If you don't have 3 rows full of 4116's, it's time to
upgrade - it's very easy to do.
eric
--
-tony
ard12(a)eng.cam.ac.uk
The gates in my computer are AND,OR and NOT, not Bill