Tandy 1000 MS-DOS Product manual

TERMS AND CONDITIONS OF SALE AND LICENSE OF TANDY COMPUTER EQUIPMENT AND
SOFTWARE PURCHASED FROM RADIO SHACK COMPANY-OWNED COMPUTER CENTERS, RETAIL
STORES AND RADIO SHACK FRANCHISEES OR DEALERS AT THEIR AUTHORIZED LOCATIONS
LIMITED WARRANTY
CUSTOMER OBLIGATIONS
A. CUSTOMER assumes full responsibility that this computer hardware purchased (the "Equipment"), and any
copies of software included with the Equipment or licensed separately (the "Software") meets the specifications,
capacity, capabilities, versatility, and other requirements of CUSTOMER.
B. CUSTOMER assumes full responsibility for the condition and effectiveness of the operating environment in which
the Equipment and Software are to function, and for its installation.
II. LIMITED WARRANTIES AND CONDITIONS OF SALE
A. For a period of ninety (90) calendar days from the date of the Radio Shack sales document received upon
purchase of the Equipment RADIO SHACK warrants to the original CUSTOMER that the Equipment and the
medium upon which the Software is stored is free from manufacturing defects. This warranty Is only applicable
to purchases of Tandy Equipment by the original customer from Radio Shack company-owned computer
centers, retail stores, and Radio Shack franchisees and dealers at their authorized locations. The warranty is
void if the Equipment's case or cabinet has been opened, or if the Equipment or Software has been subjected to
improper or abnormal use. If a manufacturing defect is discovered during the stated warranty period, the defective
Equipment must be returned to a Radio Shack Computer Center, a Radio Shack retail store, a participating Radio
Shack franchisee or a participating Radio Shack dealer for repair, alonQ with a copy of the sales document or
lease agreement. The original CUSTOMER'S sole and exclusive remedy In the event of a defect is limited to the
correction of the defect by repair, replacement, or refund of the purchase price, at RADIO SHACK'S election and
sole expense. RADIO SHACK has no obligation to replace or repair expendable items.
B. RADIO SHACK makes no warranty as to the design, capability, capacity, or suitability for use of the Software,
except as provided in this paragraph. Software is licensed on an "AS IS" basis, without warranty. The original
CUSTOMER'S exclusive remedy, in the event of a Software manufacturing defect, is its repair or replacement
within thirty (30) calendar days of the date of the Radio Shack sales document received upon license of the
Software. The defective Software shall be returned to a Radio Shack Computer Center, a Radio Shack retail store,
a participating Radio Shack franchisee or Radio Shack dealer along with the sales document
C. Except as provided herein no employee, agent, franchisee, dealer or other person is authorized to give any
warranties of any nature on behalf of RADIO SHACK.
D. EXCEPT AS PROVIDED HEREIN, RADIO SHACK MAKES NO EXPRESS WARRANTIES, AND ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE IS LIMITED IN ITS DURATION
TO THE DURATION OF THE WRITTEN LIMITED WARRANTIES SET FORTH HEREIN.
E. Some states do not allow limitations on how long an implied warranty lasts, so the above Iimitation(s) may not
apply to CUSTOMER.
III. LIMITATION OF LIABILITY
A. EXCEPT AS PROVIDED HEREIN, RADIO SHACK SHALL HAVE NO LIABILITY OR RESPONSIBILITY TO CUSTOMER
OR ANY OTHER PERSON OR ENTITY WITH RESPECT TD ANY LIABILITY, LOSS OR DAMAGE CAUSED OR
ALLEGED TO BE CAUSED DIRECTLY OR INDIRECTLY BY "EQUIPMENT" OR "SOFTWARE" SOLD, LEASED,
LICENSED OR FURNISHED BY RADIO SHACK, INCLUDING, BUT NOT LIMITED TO, ANY INTERRUPTION OF
SERVICE, LOSS OF BUSINESS OR ANTICIPATORY PROFITS OR CONSEQUENTIAL DAMAGES RESULTING FROM
THE USE OR OPERATION OF THE "EQUIPMENT" OR "SOFTWARE." IN NO EVENT SHALL RADIO SHACK BE
LIABLE FOR LOSS OF PROFITS, OR ANY INDIRECT, SPECIAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
ANY BREACH OF THIS WARRANTY OR IN ANY MANNER ARISING OUT OF OR CONNECTED WITH THE SALE,
LEASE, LICENSE, USE OR ANTICIPATED USE OF THE "EQUIPMENT" OR "SOFTWARE."
NOTWITHSTANDING THE ABOVE LIMITATIONS AND WARRANTIES, RADIO SHACK'S LIABILITY HEREUNDER FOR
DAMAGES INCURRED BY CUSTOMER OR OTHERS SHALL NOT EXCEED THE AMOUNT PAID BY CUSTOMER FOR
THE PARTICULAR "EQUIPMENT" OR "SOFTWARE" INVOLVED.
B. RADIO SHACK shall not be liable for any damages caused by delay in delivering or furnishing Equipment and/or
Software.
C. No action arising out of any claimed breach of this Warranty or transactions under this Warranty may be brought
more than two (2) years after the cause of action has accrued or more than four (4) years after the date of the
Radio Shack sales document for the Equipment or Software, whichever first occurs.
D. Some states do not allow the limitation or exclusion of incidental or consequential damages, so the above
limitation(s) or exclusion(s) may not apply to CUSTOMER.
IV. SOFTWARE LICENSE
RADIO SHACK grants to CUSTOMER a non-exclusive, paid-up license to use the TANDY Software on one computer,
subject to the following provisions:
A. Except as otherwise provided in this Software License, applicable copyright laws shall apply to the Software.
B. Title to the medium on which the Software is recorded (cassette and/or diskette) or stored (ROM) is transferred to
CUSTOMER, but not title to the Software
C. CUSTOMER may use Software on one host computer and access that Software through one or more terminals if
the Software permits this function.
D. CUSTOMER shall not use, make, manufacture, or reproduce copies of Software except for use on one computer
and as is specifically provided in this Software License Customer is expressly prohibited from disassembling the
Software.
E. CUSTOMER is permitted to make additional copies of the Software only for backup or archival purposes or if
additional copies are required in the operation of one computer with the Software, but only to the extent the
Software allows a backup copy to be made. However, for TRSDOS Software, CUSTOMER is permitted to make a
limited number of additional copies for CUSTOMER'S own use.
F. CUSTOMER may resell or distribute unmodified copies of the Software provided CUSTOMER has purchased one
copy of the Software for each one sold or distributed. The provisions of this Software License shall also be
applicable to third parties receiving copies of the Software from CUSTOMER.
G. All copyright notices shall be retained on all copies of the Software.
V. APPLICABILITY OF WARRANTY
A. The terms and conditions of this Warranty are applicable as between RADIO SHACK and CUSTOMER to either a
sale of the Equipment and/or Software License to CUSTOMER or to a transaction whereby Radio Shack sells or
conveys such Equipment to a third party for lease to CUSTOMER.
B. The limitations of liability and Warranty provisions herein shall inure to the benefit of RADIO SHACK, the author,
owner and or licensor of the Software and any manufacturer of the Equipment sold by Radio Shack.
VI. STATE LAW RIGHTS
The warranties granted herein give the original CUSTOMER specific legal rights, and the original CUSTOMER may
have other rights which vary from state to state. 12/84

Tandy 1000 Technical Reference Manual
Tandy 1000 Computer
25-1504

Tandy@ 1000 BIOS
© 1984 Tandy Corporation and
Phoenix Compatibility Corporation
All Rights Reserved.
Some
of the system software in the Tandy 1000 is retained in read-only
memory
(ROM) format. All portions of this system software, whether in the
ROM format or other source code format, and the ROM circuitry, are
copyrighted and are the proprietary and trade secret information
of Tandy
Corporation. Use, reproduction, or publication
of any portion of this material
without the prior written authorization
by Tandy Corporation is strictly pro-
hibited.
Tandy@ 1000 Technical Reference Manual
© 1985 Tandy Corporation
All Rights Reserved.
Reproduction
or use without the express written permission from Tandy
Corporation,
of any portion of this manual is prohibited. While reasonable ef-
forts have been taken to assure its accuracy, Tandy Corporation assumes no
liability resulting from any errors or omissions
in this manual, or from the use
of the information contained herein.
The FCC wants you to know ...
Warning: This equipment generates, uses, and can radiate radio frequency
energy and if not installed and used
in accordance with the instructions
manual, may cause interference to radio communications. It has been tested
and has been found to comply with the limits for Class Acomputing devices
pursuant to Subpart J
of Part 15 of FCC Rules, which are designed to provide
reasonable protection against such interference when operated
in a commer-
cial environment. Operation
of this equipment in aresidential area is likely to
cause interference in which case the user at his own expense will
be required
to take whatever measures may
be required to correct the interference.
Tandy is aregistered trademark
of Tandy Corporation.
IBM and PCjr are is aregistered trademarks
of
International Business Machines Corporation.
10 9 8 7 6 5 4 3 2 1

Tandy 1000
Table of Contents
Technical Reference Manual
Introduction .
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 3
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 5
Mechanical ..........................................
.. 6
Connector Pin Assignments .
1000 and IBM I/O Bus Cross Reference Chart .
Bus Interface Specifications .
7
10
13
Theory of Operation 17
Main Logic Board 17
IFL Equations. ....................................... .. 21
Introduction to the Video System Logic. . . . . . . . . . . . . . . . . . . . .. 38
Video System Modes 45
Display Modes 45
Operating Modes 46
Graphics
Mode. .................................. .. 47
System Logic Registers ................................
.. 50
Video Array Register "50
Palette Mask
Register. ............................. .. 50
Border Color
Register. ............................. .. 51
Mode Control Register ............................. .. 51
Palette Register. .................................. .. 52
Video
Memory Map Register .. . . . . . . . . . . . . . . . . . . . . . . .. 53
Mode Register. ...................................
.. 55
Color Select Register. ..............................
.. 55
Status Register ..........
.. 56
CRT/Processor Page Register. .......................
.. 57
General
Memory Information. ........................... .. 58
Mode Selection
Summary. .......................... .. 58
I/O
Map 58
System Configuration Port 59
ROM 59
RAM 59
Detailed Memory
Map 60

Tandy 1000 Technical Reference Manual
256K Memory Expansion Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 73
Jumper Options 73
Theory
of Operation "74
RS-232 Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 77
Introduction "77
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 78
300 Baud Modem 85
Introduction 85
Theory
of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 86
Mouse Clock/Calendar Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 91
Introduction " 91
Theory of Operation Hardware . . . . . . . . . . . . . . .. 91
Theory of Operation Software . . . . . . . . . . . . . . . . . . .. 92
Keyboard Assembly
101
Keyboard Specifications 101
Key Code Chart 102
Keyboard Timing 104
Keyboard Layout 105
Appendices
AI Comparative Tables for IBM
PC and PCjr Computers
BI Printer Specifications
CI Intel Corporation Specifications:
8088-2 8237A-5
8253-5 8255A-5
8259A-8 8272A .
8284A-1
01 Texas Instruments Specifications:
76496
EI Motorola Semiconductors Specifications:
MC6845
FI Teac Disk Drive Manual
GI Connectors and Pin Designations
HI Schematics

Tandy 1000 Technical Reference Manual
INTRODUCTION TO THE TANDY 1000 COMPUTER
The Tandy 1000 Computer is modular in design to allow maximum flexibility
in system configuration. The computer consists of aMain Unit, adetachable
keyboard with coiled cable, and amonitor. The Main Unit
is supplied with one
internal floppy disk drive.
(A second floppy disk drive is optional.) The stan-
dard types of monitors used with the Tandy 1000 are the monochrome com-
posite and the color
RGB monitor. Since these units are modular, they may
be placed on top of the Main Unit or at any convenient location.
Internal storage
is expanded by adding asecond 51/4" floppy disk drive. Each
disk drive has acapacity of 360K bytes formatted.
The Tandy 1000 has astandard 128K of system RAM. An optional DMA/RAM
board allows the Tandy 1000 to be expanded
in increments of 128K of RAM.
This board
will fit into one of the expansion slots. With two fully populated RAM
boards installed, the Tandy 1000
will have 640K bytes of maximum RAM allow-
ed by the system memory map.
Other features include aparallel printer port, two built-in joystick interfaces,
aspeaker for audio feedback, and alight pen interface.
The Main Unit is the heart of the Tandy 1000. It houses the Main Logic
Assembly, system power supply, and floppy disk drives.
The Main Logic Assembly is alarge board mounted to the bottom of the Main
Unit and interconnected to the keyboard, power supply, and disk drives by
aseries of cables. The illustration
in Figure 1shows the major components
of aTandy 1000 system.
The Power Supply is a54W switching regulator type, designed to provide ade-
quate power capacity for afully configured system using
all the option slots.
The Floppy Disk Drive uses 51/4" double-sided, double-density diskettes to read,
write, or store dpta. These are soft sector diskettes.
The Disk Drive assembly
is installed in the standard unit. The floppy disk stores approximately 360K
bytes (formatted) of data.
All system programs, with the exception of the system
startup sequence, are stored on disk.
Either amonochrome or acolor display may be used with the Tandy 1000.
The monochrome monitor
is ahigh-resolution green phosphor display which
provides excellent visual quality.
It features a 12" screen with an anti-glare sur-
face. Each display
is capable of 25 lines of 80 characters. The character matrix
is 8wide x 9 high.

Tandy 1000 Technical Reference Manual
Tandy 1000 System
Figure 1
2

Tandy 1000
SPECIFICATIONS
Technical Reference Manual
Processor: Intel 8088
Dimensions:
6x17 x13 %inches (HWD)
Weight:
17 Ibs. 4 oz. with 1Disk Drive
Power Requirements:
120 VAC, 60 Hz, 1Amp maximum
With 2Floppy Disk Drives, 2Memory Cards, and RS-232:
AC Current: 0.7 -0.8 Amps with Floppy doing R/W tests.
Leakage Current: 0.5 mA
Disk Drive:
Idle + 5
VDC 0.23 Amps +12 VDC 0.106 Amps
R/W 0.286 Amps 0.295 Amps
R/W 0.2 Minimum 0.550 Max.
Main Logic Board: + 5 VDC 4.07 Amps +12 VDC 0.056 Amps
Main Logic Board Option Cards:
-12 VDC 0.032 Amps
Environment:
Air Temperature
System
ON: 60 to 90 degrees F(15.6 to 32.2 degrees C)
System OFF: 50 to 110 degrees F(10 to 43 degrees C)
Humidity
System ON-OFF:
8% to 80%
Disk Drive Specifications
Power:
Supply
Voltage
Ripple
o to 50 kHz
Tolerance
Including Ripple
Standby Current
Nominal
Worst Case
Operating Current
Nominal
Worst Case
Environment:
Temperature
Operating
Nonoperating
Relative Humidity
Operating
Nonoperating
+5 VDC Input +12 VDC Input
100 mV
100 mV
+/-5% +/-5%
600 mA
400 mA
700 mA
500 mA
600 mA
900 mA
700 mA
2400 mA
50 to 122 degrees F(10 to 44 C)
-40 to 140 degrees F (-40 to 60 C)
20% to 80% (noncondensing)
5% to 95% (noncondensing)
3

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Tandy 1000 Technical Reference Manual
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Tandy 1000 Technical Reference Manual
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6

Tandy 1000 Technical Reference Manual
Connector Pin Assignments
J2 -Speaker Interface
(2-Pin Vertical Header)
-Sound 2-Ground
J3
-Right Joystick
(6-Pin
Rt. Angle Circular Din)
1 Y Axis 2XAxis
3-Ground 4Switch 1
5-
+5 VDC
6Switch 2
J4 -Left Joystick
(6-Pin
Rt. Angle Circular Din)
1 Y Axis 2- X Axis
3-Ground 4Switch 1
5-
+5 VDC 6-Switch 2
J5
-Keyboard Interface
(8-Pin
Rt. Angle Circular Din)
1KBDDATA 2KBDBUSY*
3Ground 4KBDCLK
5
+5 VDC 6KBDRST
7MULTIDATA 8MULTICLK
J6 -Floppy Disk Interface
(Dual 17-Pin Vertical Header)
1Ground 2NC
3Ground 4NC
5Ground 6NC
7Ground 8INDEX*
9Ground 10
DSO*
11 Ground 12 DS1
13 Ground 14 NC
15 Ground 16 MTRON*
17 Ground 18 DIR*
19 Ground 20 STEP*
21 Ground 22 WRDATA*
23 Ground 24 WEN*
25 Ground 26 TRKO*
27 Ground 28 WRPRT*
29 Ground 30 RDDATA*
31 Ground 32 SIDESELECT*
33 Ground 34 DRVRDY*
7

B01 -Ground
B02 -
RESET
B03 - +5 VDC
B04 -IR2
B05 - (- 5 VDC)
B06 -FDCDMARO*
B07 -
-12 VDC
B08 -AUDIOIN
B09 - +
12 VDC
B10 -Ground
B11 -MEMW*
B12 -MEMR*
B13
-IOW*
B14 -IOR*
B15 -(DACK3 *)
B16 -(DRQ3*)
B17 -(DACK1
*)
B18 - (DRQ1 *)
B19 -REFRESH*
B20 -
ClK
B21 -RFSHRQ
B22 -BREQ*
B23
-IR5
B24 -IR4
B25 -IR3
B26 -FDCDACK*
B27 -DMATC
B28 -ALE
B29 -
+5 VDC
B30 - OSC
B31 -Ground
Tandy 1000
J7 - DC POWER
(9-PIN VERTICAL HEADER)
1
+5 VDC
3 +5 VDC
5Ground
7Ground
9 +
12 VDC
J8,J9,J10 -Expansion Interface Connectors
(Dual 31-Pin Card Edge)
A01 -NMI
A02 -
07
A03 - 06
A04 - 05
A05 - 04
A06 - 03
A07 - 02
A08 - 01
A09 - 01
A10 -READY
A11 -AEN
A12 - A19
A13 - A18
A14
-A17
A15 -A16
A16 - A15
A17
-A14
A18 - A13
A19 - A12
A20 -
A11
A21
- A10
A22 - A09
A23 - A08
A24 - A07
A25 - A06
A26 -A05
A27 - A04
A28 - A03
A29 - A02
A30 -
A01
A31 - AOO
2
4
6
8
Technical Reference Manual
+5 VDC
Ground
Ground
-12 VDC
Note: Signals in parentheses on J8, J9, and J10 are shown for PC Com-
patible Reference only and are not used
on the main logic board of the
Tandy 1000.
8

Tandy 1000 Technical Reference Manual
J11 -Parallel Interface
(34-Pin Card Edge)
1PPSTROBE* 2Ground
3PPDATAO 4Ground
5PPDATA1 6Ground
7PPDATA2 8Ground
9PPDATA3 10 Ground
11 PPDATA4 12 Ground
13 PPDATA5 14 NC
15 PPDATA6 16 Ground
17 PPDATA7 18 Ground
19 PPACK* 20 Ground
21 PPBUSY 22 Ground
23 PPPAEM 24 Ground
25 PPBUSY* 26 NC
27 Ground 28 PPFAULT
29 NC 30 PPINIT* .
31 Ground 32 PPAUTOFEED*
33 Ground 34 NC
J12 -Light Pen
(9-Pin Connector Male
Rt. Angle D-Subminiature)
1
+5 VDC
2Ground
3LPIN 4LPSW*
5NC 6NC
7NC 8NC
9NC
J13 -
RGBI Video
(9-Pin Socket
Rt. Angle D-Subminiature)
1Ground 2Ground
3Red 4Green
5Blue 6Intensity
7+12 VDC 8HSYNC
9VSYNC
J14 -Composite Output
(Dual
Rt. Angle RCA-Type Phone Jack)
A - Video
B - Audio
9

Tandy 1000
1000 and IBM I/O Bus Cross Reference Chart
Technical Reference Manual
Pin No.
B18
B17
B16
B15
B05
B21
B22
B08
10
Signal Name
DRQ1 *
DACK1 *
DR03*
DACK3*
-5VDC
RFSHRQ*
BREQ*
AUDIOIN
Description
IBM -This signal is always available on the
IBM
PC.
TANDY 1000 -DMA request 1 is available
only
on the I/O bus when the Memory/DMA
board
is installed.
IBM -This signal
is always available on the
IBM
PC.
TAN DY 1000 -DMA grant 1 is only
available
on the I/O bus when the
Memory/DMA board
is installed.
IBM -This signal
is always available on the
IBM
PC.
TAN DY 1000 -DMA request 3ionly
available
on the I/O bus when the
Memory/DMA board
is installed.
IBM -This signal
is always available on the
IBM
PC.
TAN DY 1000 -DMA grant 3 is only
available
on the I/O bus when the
MemorylDMA board
is installed.
IBM - - 5VDC
is always available.
TAN DY 1000 - - 5VDC is not installed on
the I/O bus, but amodification
is available
through
an authorized repair center.
IBM -This signal functions
as arefresh re-
quest on the I/O bus, but is labeled Interrupt
Request
7.
TANDY 1000 -Same function as on the IBM
PC, but different pin designation.
IBM -This signal functions
as abus request
on the I/O bus, but is labeled Interrupt Re-
quest 6.
TANDY 1000 -Same function as on the IBM
PC, but different pin designation.
IBM -Reserved
TANDY 1000 -Audio input
is supplied from
an optional board on the I/O bus to a
multiplexer
on the main logic board for an
output to the external speaker.

Tandy 1000 Technical Reference Manual
1000 and IBM I/O Bus Cross Reference Chart (Continued)
Pin No.
B06
B26
B27
Signal Name
FOCOMARQ*
FOCOACK*
OMATC
Description
These signals are functionally the same as
those on the IBM PC, however, the Tandy
1000 was designed with
an FOC Controller
on the main logic board and the OMA Con-
troller
on the optional memory board. The
IBM PC has the OMA Controller on the
main logic board and the optional
FOC Con-
troller
on the I/O bus.
Note:
All other pins are identical to the IBM PC. See Section 3for the
connector pin assignments.
11

Tandy 1000
12
Technical Reference Manual

Tandy 1000 Technical Reference Manual
BUS INTERFACE SPECIFICATIONS
This specification IS for the primary bus on the Tandy 1000 main logic board,
which also
is available to the option board connectors. The specification
describes the signals
in the following manner. See Figures 5and 5.1.
•The following signal nomenclature IS used In the schematic and literature.
Signals designated with the suffix" *" are logically; 'true low" (normal in-
active state is high); if they are not so designated, the signal is logically' 'true
high,"
•Dlrection-- input or output-is referenced to the CPU.
•Brief functional description of the signal,
•Description of the
"drive" or "load" characteristics of the signal This in-
cludes the specific source by IC type and reference designator, drive
capability for
"output" signals, and actual load for "input" signals The
drive/load
is defined in "unit loads" and speCified as "high/low." This
speCification is for the main logiC board only. Some signals have an alter-
nate source, an external bus master such as the DMA.
• 1 Unit Load (UL) is defined as loh ,04mA @2.4V
101 = 1,6mA @0,5V
Signal Listing
AOO - A19 0ADDRESS
00-07
ALE
10W*
IOR*
MEMW*
MEMR*
CLK
OSC
NMI
SOURCE: U41, U42, U61
Drive -65/15
UL
Latch Strobe -ALE
Output Enable -AEN
Alternate external
source
I/O DATA SOURCE: U62
Drive - 37/15 UL
Di rection Control - R0*
(CPU read signal)
Enable -DEN *
oADDRESS LATCH STROBE SOURCE: U46
oI/O WRITE STROBE Drive -50/7,5 UL
oI/O READ STROBE Output Enable -AEN
o MEMORY WRITE STROBE Pull-Up -4.7K ohms
o MEMORY READ STROBE Alternate external source
oCPU CLOCK 4.77MHz, 33% duty cycle
SOURCE:
U82
Drive -75/7.5 UL
oOSCILLATOR 14.32MHz, 50% duty cycle
SOURCE: U82
Drive -75/7.5
UL
NON-MASKABLE To System NMI
INTERRUPT Load: 1/1 UL, U117
13

Tandy 1000 Technical Reference
Manual
AUDIO OUT 0
From Extemal Sound Source
Load:
10k ohms.
To Extemal Source
Drive: 1.25 Volts
P-P into 10K
INTERRUPT REQUEST#4
SOURCE: OPEN-COLLECTOR
OR 3-STATE BUFFERS
Load: 1 ULand 1.0K ohm
pull-up. 10/0.9 UL
Set LOW by Peripherals (I/O or
Memory) to extend READ or
WRITE cycles.
Power On or Manual
SOURCE:
U82
Drive: 75/7.5 UL
From extemal masters
Load: 1 ULand 10K ohm
pull-up. 10/0.9 UL
To extemal masters
SOURCE: U82
Drive -75/7.5
UL
INTERRUPT REQUEST#2 To system interrupt controller
INTERRUPT REQUEST#3 Load: 1
UL and 2.2K
pull-down
oBUS GRANT
IBUS REQUEST
oSYSTEM RESET
ISYSTEM WAIT
AEN
IR4
AUDIO IN
BREQ*
IR2
IR3
RESET
READY
1MOS load 40/160 UL
Dedicated output
acknowledges from DMA.
Drive:
8237 A-5/9517A
2/2
UL
Load: 8237 A-5/9517A
REFRESH*
DACK1 *
FDCDACK*
DACK3*
DR03
DR01
The following are not sourced by the CPU but are to be SOURCED (0) Output
or LOADED (I) Input by an extemal DMA source
RFSHRQ IREQUEST DMA Dedicated input requests
CHANNEL#O to DMA
REQUEST DMA
CHANNEL#1
FDCDMARQ IREQUEST DMA
CHANNEL#2
REQUEST DMA
CHANNEL#3
o ACKNOWLEDGE DRQO*
o ACKNOWLEDGE DRQ1 *
o ACKNOWLEDGE DRQ2 *
o ACKNOWLEDGE DRQ3*
DMATC o
TERMINAL COUNT
Used by DMA Controller to
indicate Terminal Count
reached.
Drive: 2/2 UL
+5VDC +5VDC ± 4% 3.0 Amps available on the bus.
+12VDC +12VDC ± 5% 0.5 Amps available on the bus.
-12VDC -12VDC + 8.3% - 25% 0.06 Amps availabie on the bus.
GROUND Power Retum for + 5, +12, -12 VDC.
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