Tandy Professional Forum   Section: T1000/1400/3000/4K
Subject: 4K Controller Card   Total messages: 4
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#62605   1 Reply   11/01/96   13:06:05
From: Phillip Garnes, 70771,1105
To:   All

    I've been given an old Tandy 4000 ,sans cords, keyboard and
monitor, that hasn't been in use for the last three years.  After
making the necessary connections with some used equipment I get a
seek error in "diskette drive 0".  It has 3.5" and 5.25" floppy
drives and an old ST-225 hard drive.  I suspect that I may have
connected the three (3) ribbon cables  between  the controller
card and the drives improperly.  On the card there are two 34-pin
connections labeled J1 & J5 and two 20-pin connections labeled J4
& J3.  Does anyone have an idea as to their proper connection?
Thanks for any help.

Phillip Garnes


#62606   Reply to #62605   1 Reply   11/02/96   02:21:14
From: F. Barry Mulligan, 70035,140
To:   Phillip Garnes, 70771,1105

Phillip,

    From your description, I suspect you have the # 25-4060 Dual Controller
board. Reading from the left, the connectors are:
        J3 (20 pin) - secondary HD data
        J4 (20 pin) - primary HD data
        J5 (34 pin) - HD controller
        J1 (34 pin) - floppy controller/data
The HD cables (J4 & J1) come out to the left of the connector, while the
floppy cable ordinarily feeds to the right (it's not polarized, so check
the pin & socket numbers to be sure). The floppy cable should run to the
bottom drive first (typically the 5.25" drive), then on to the top drive.
There should be a twist in several lines between the drives (both are
jumpered as "B" drives, the twist makes the adjustment for the top one).

    The controller board jumpers should be:
        E2-E3  select primary addrs '3Fx for the floppys
        E5-E6  select primary addrs '1Fx for the HDs
        E7-E8  always connected

    A few notes - you'll probably find that the 3.5" floppy is actually
an oddball with power delivered via the 34 pin socket. It sits in an
adapter tray that allows it to be mounted in a 5.25" space and contains
a small pc board that combines the power and data lines. This arrangement
allows either type of drive to be mounted in either position with standard
cabling. The only problem arises when you have to replace a failed 3.5"
drive with a current standard one (I kept the adapter tray, minus the board,
and fabricated a new data cable).

    The T4000 motherboard contains a floppy controller, which can be used
in a non-HD configuration. The connector (J4) is to the left of the drive
tower. When using the dual controller board to run both the HD and floppies,
the motherboard controller must be disabled. The manual says to remove the
jumper at E5-E6-E7, but this is wrong. Set it to E6-E7 (nominally the
secondary address position). If this is not done, the two controllers will
fight it out and you'll get either errors or nothing.
    During your testing, you might want to pull the HD controller board and
connect the floppies to the motherboard controller. In this case, set the
jumper to E5-E6.

    You described the HD as "an old ST-225", but the standard drive was a
40-megger (Microscience HH-1050 or CDC 94205-51). You might want to check
it before reformatting. In particular, if this was a Radio Shack store
POS/inventory machine, you might find a quite servicable Xenix system
installed. There were several thousand of these on the surplus market when
Tandy upgraded their store systems. They earned a reputation as solid,
run-forever machine (why do I suddenly have the feeling I just put a curse
on my 9-year-old, 24 hr/day machine?).

                                                      /* barry /&


#62624   Reply to #62606   1 Reply   11/09/96   19:21:01
From: Phillip Garnes, 70771,1105
To:   F. Barry Mulligan, 70035,140


Barry,
     Thanks for your quick reply and  __very__  detailed
description of the different controller card components in my 4K.
 I made all the connections as outlined in your reply but it
seems my problem now is that the hard drive (it is a Seagate
ST-225) has "gone south" and refuses to be recognized - the drive
light stays on but when I try to access I get an "invalid drive
specification" error message.  This may not be worth the trouble
so unless I can get a 5.25 HD real cheap or free it's scrap.
Thanks again for the help.  BTW, while the 4K was going through
POST, as it counted off available memory, it only registered 640K
Base Memory and 00000K Extended.  I'm puzzled because there are 4
SIMMs onboard butI don't know how much RAM is on each one.  I
should think it would show at least 1MB. Thanks again

Phil


#62625   Reply to #62624   11/10/96   15:22:19
From: F. Barry Mulligan, 70035,140
To:   Phillip Garnes, 70771,1105

Phil,

    The "Invalid drive specification" message usually means that you have
entered a drive letter greater than the system recognises. You might want
to check for a "lastdrive=.." statement in CONFIG.SYS and that the CMOS
has the correct definition for drive C (an ST-225 is type 2). If you don't
have SETUP.COM on a floppy, the Basic statements -
        OUT &H70, 25 : PRINT INP(&H71)
will return the CMOS stored drive type.

    It is possible that the drive is simply unformatted, or formatted with
a standard that DOS doesn't recognise. If it was a Radio Shack POS machine,
the system was a Unix varient, which should have been erased before sale.
If you can't boot from or access the hard disk, try reformatting before
consigning it to the junk pile.

    As to the memory, the POST display is correct for a machine with one
meg of memory. The BIOS (and unaugmented DOS) only recognises the first
640K. The four SIMMs are each 256K, the factory issue complement.

                                                         /* barry /&


