Tandy 1000 Technical Reference Manual

Tandy 1000
Technical Reference Manual
8272A
A.C. CHARACTERISTICS (Continued)
(TAO°C to +70°C,V
cc
=
+ 5.0V
1:10%)
WRITE CYCLE
Symbol
Parameter
Typ.1
Min.
Max. Unit
Notes
'AW
Select Setup to WRl
0
Select Hold from WR+
0
WR Pulse Wloth
250
Data Setup to WA' 150
IWO
Data Hold from WR'
INT Delay from RO'
INT Delay tram WR'
DMA
ORa CyCle Period 13
"5
Note 6
DACK. 10 DRQ, 200
DRQ' 10 RD.
800
Note 6
DRO' 10 INR,
200
Note 6
ORO' to RD' or WR'
12
Note G
FDD INTERFACE
WeK Cycle Time 20r4
f.'~-'
~~~:~ Note 2
1 nr 2
WCK High Time 250 eo 350
Pre-Shilt Delay from WeK' 100
WOA Delay from WeK'
20 100
Write Oala Wldlh
IWCH
50
WE' to WCK' or WE. to WCK. Delay
20 100
Window Cycle Time
MFM
MFM
=
Window Setup to ROO' 15
Window Hold from ROD. 15
ROD Acllye Time (HIGH) 40
FDD SEEKJDIRECTtONISTEP
IUS
USa' Setup to RWiSEEK'
12
Note 6
USOI Hold after RW/SEEK.
15
Note 6
ISO
RWISEEK Setup to LeTIDIR
Note 6
RW/SEEK Hold from LCT'DIR 30
Note 6
lOST
LCTIDIR Selup 10 FR/STEP'
Note 6
'STO
LCTIDIR Hold from FR/STEP.
24
Note 6
'STU
DS21 Hold from FR/Step_
"'
Nole 6
tSTP
STEP Actlye Time (High)
Note 6
STEP Cycle Time
33
Nole 3. 6
FAULT RESET ACllye Time (High) 8
10
"$
Note 6
1iOX
INDEX Pulse Width 10 ICY
Terminal Count Width 1CY
NOTES
1, Typical yalues for TA= 25
a
C and nominal supply voltage
2, The former values are used for standard floppy and the latter values are used for mindloppies
3 tsc = 33 /-ls min, IS for dilferent drive units In the case of same unit. tsc can be ranged from 1 ms 10 16 ms with a MHz clock period. and 2 ms
to 32 ms with 4 MHz clock. under software control
4 From 2.0V to + 2.0V
5 At 4 MHz, the clock duty cycle may range from 16% to 76%, Using an 8 MHz clock the duty cycle can range from 32% to 52%. Duty cycle is
defined as: D.C = 100 (tCH - ICY) with typical rise and fall times of 5 ns
6 The specified values listed are for an 8 MHz clock period. Multiply timings by 2 when using a 4 MHz clock period
6-237

Tandy 1000 Specifications

General

Processor	Intel 8088
Processor Speed	4.77 MHz
RAM	128 KB (expandable to 640 KB)
Operating System	MS-DOS 2.11
Manufacturer	Tandy Corporation
Release Year	1984
Storage	Single or double 5.25" floppy disk drive (360 KB), optional hard drive
Sound	Tandy 3-voice sound
Ports	Parallel, Serial
Graphics	CGA (Color Graphics Adapter)
Graphics Modes	320x200, 640x200