19 Jul
1998
19 Jul
'98
2:21 a.m.
Lawrence Walker wrote:
To clearify, a Model II requires an additional CPU
card. This is a MC68000 CPU
with a daughter card or two that may contain from 128K to 1 Meg of RAM. It
depends. There were several memory card configurations. I have some from
the 128K to the 1 Meg varity. The really rare ones are the 4 Meg memory cards.
There was never a Tandy 4 Meg card. Bob Snapp had boards to take a 16
or 6000 up to 8 Meg, but the memory management permitted only a max of
1 Meg "user" RAM -- the rest could be used as RAM disk, permitting a
/dev/swap far larger and faster than Tandy hardware. It was damned
impressive to see his stuff at the Tangent conference in Fort Worth in
1986, 15 terminals (plus console) filePro databases faster than a stock
system could with three users.
In addtion, You should have a HD controller. This card
will have the WD1010
or WD1020 chipset. It will allow you to attach up to 2 MFM drives. The
standard MFM cabling has one "Control" cable that is dasiy-chained to all
drives. Then the smaller "Data" cable is connected directly from the HD to
the drive controler card. I have not see a controler card that was able
to use more than two HDs at a time. All the Tandy manufactured card would
use the WD1010 chipset which allows up to 70Mb HDs. Some after-market
people upgraded to the WD1020 chipset which increased the HD capacity to
the 130 ro 150Mb range. I dont remember the exact upper limit although
they did not make MFM drives much larger that 150 Mb as I recall. All the
HDs should be free standing. Only a possiable drive select jummper should
differ the HDs in the external cases.
Actually, except for the 6000HD which would only accept one external
drive after the internal, all hard disk subsystems for the Model
II/12/16/6000 line would permit four external drives, either all 8.4
Meg (the 8" Shugart "original" system) or any combination of 5, 12, 15,
35 or 70 MB (the later 5.25" system). At least that was the case with
official Tandy hard drives.Those latter would also attach in quantities
up to four to any of the Model One/3/4 product line or the Color
Computer. That's what always surprised me when PCs and compatibles
were limited to two drives, at least until SCSI and EIDE.
--
Ward Griffiths <mailto:gram@cnct.com> <http://www.cnct.com/home/gram/>
They say that politics makes strange bedfellows.
Of course, the main reason they cuddle up is to screw somebody else.
Michael Flynn, _Rogue Star_