Tandy 1000 Technical Reference Manual

Tandy 1000
Technical Reference Manual
For the straddle erase head, the write gate and the erase gate signals
have the same timing. The tunnel erase or the straddle erase produces
a guard band between the tracks preventing deterioration of the SIN
ratio resulting from a off-track (positioning error). It also ensures
disk interchangeability.
The WRITE DATA input pulse is latched by the data latch. And
appropriate write current is supplied to the read/write head by turning
on and off the two write drivers alternately. When the write driver is
active, no read data pulse is generated by the read circuit.
WRITE GATE input
Write gate (WG)
(UI ,pin 16)
Erase gate (EG)
(TP2)
SIDE ONE SELECT
WRITE DATA
Data latch output
I \1
r-t Erase on delay • rEUSe off
JI ~ delay
~ ~ L
-,--------,,-------r
_L ----------11-- L
Write driver output _ L ~ . J\ "t\__~
(Ul,pin 21 or 22) ----- ~ ~ -vr'r- ~ -------------
Write current
Magnetization on
disk
Note:
Magnetized
previously
Solid line of the Erase gate (EG) signal shows the tunnel
type and dotted line shows the straddle erase type. Erase
delay and Erase off delay are applied only for the tunnel
type.
(Fig.306) Write circuit waveforms
- 313 -
erase
on
erase

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