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Most, if not all, users of the new Tandy 1400LT will also be users of
other MS-DOS machines, and have a bunch of software, data, etc., on the
standard 5 1/4" 360K disks. The information included here will permit these
users to make a cable that will connect the 1400LT DB37 port to a standard
disk drive 34 pin edge connector.
The setup described here has been in use for a long enough time to
indicate that there are no apparent problems using this cable. The 5 1/4"
drive being used is a Mitsubishi, and is fairly standard in comparison to
others, such as TEAC, Fuji, Shugart, etc.
DISCLAIMER! - ALTHOUGH WE HAVE NO PROBLEMS WITH THIS SETUP, IT GOES WITHOUT
SAYING THAT THERE IS NO GUARANTEE IT WILL WORK WITH ALL DRIVES... THE DB37
PINOUT INFORMATION IS FROM 'PRELIMINARY' FACTORY SCHEMATICS. NO LIABILITY FOR
DAMAGE TO YOUR DRIVES, OR THE 1400LT, WILL BE ASSUMED BY EITHER MYSELF, NOR
ANYONE AT TANDY!!
1400LT DB37 DRIVE 34 EDGE
N.C. [ 1]
N.C. [ 2]
Ground [ 3]-------------------[ 7]
Ground [ 4]-------------------[ 9]
Ground [ 5]-------------------[11]
Ground [ 6]-------------------[13]
Ground [ 7]-------------------[15]
Side 1 Select [ 8]-------------------[32]
Direction [ 9]-------------------[18]
Write Protect [10]-------------------[28]
Read Data [11]-------------------[30]
Write Data [12]-------------------[22]
Write Gate [13]-------------------[24]
N.C. [14]
Drive Select 3 [15]-------------------[14]
N.C. [16]
N.C. [17]
N.C. [18]
N.C. [19]
N.C. [20]
N.C. [21]
N.C. [22]
N.C. [23]
Index [24]-------------------[ 8]
Track 00 [25]-------------------[26]
Step [26]-------------------[20]
Motor on/enable [27]-------------------[16]
N.C. [28]
N.C. [29]
N.C. [30]
N.C. [31]
Ground [32]-------------------[17]
N.C. [33]
Ground [34]-------------------[19]
Ground [35]-------------------[21]
Ground [36]-------------------[23]
Ground [37]-------------------[25]
(This illustration should not be assumed as a 'straight through' connection
from the DB37 to the Edge 34... several of the lines 'cross over', or connect
to pins that are not possible with a cable such as flat ribbon, unless the
conductors are separated and individually connected.)
Note that DB 37 pins run from right to left across the top row and then
from right to left on bottom row looking at pins on back of the 1400 LT,
while the edge connector on drive has staggered pins with number 2 on com-
ponent side of most drives and a key slit between 4 and 6. Drive should be
set for drive select #3, no connection at MUX and HS shorted for the R/W head
to be loaded when the Drive Select line is activated. In the CONFIG.SYS file
the line DEVICE = DRIVER.SYS should be included along with a copy of
DRIVER.SYS on the boot disk. Apparently, DRIVER.SYS does not require any
parameters to be set. The machine will boot up on drive A: and the 5 1/4
drive will be drive C: with the usual 370k of space.
Note that there is no provision for disk drive power from the 1400LT DB37
port... the drive must be connected to it's own power source. A handy case
with power supply would be one like is used for the external drives on the
Tandy Color Computer. The external drives sold by Radio Shack for the '1000'
series machines DO NOT have the required power supply.
In addition to the information on the disk drive DB37 port, we are also
including the pinout for the Serial port DB9 connector for those who may wish
to make their own serial cables...
Serial DB9 port connections
[1] CD Carrier Detect
[2] RxD Receive Cata
[3] TxD Transmit Data
[4] DTR Data Terminal Ready
[5] Gnd Ground
[6] DSR Data Set Ready
[7] RTS Ready to Send
[8] CTS Clear to Send
[9] RI Ring Indicator
The required connectors are NOT available at your local Radio Shack store.
Although a ribbon type edge 34 pin is stocked by most Radio Shack stores, it
is not the highest quality (tin rather then gold contacts). Connectors may be
purchased from several sources... JAMECO, JDR, and others who advertize in the
'Computer Shopper' and other general computer magazines, such as BYTE.
Special thanks goes out to Ted Juszcak who spent more than a few hours
conducting several experiments with cables, ribbons, cutters, soldering irons,
and a few choice words, getting the final product into a useable format...
Uploaded on October 31st by Clay Howe - CIS 72157,2773