Toshiba T-Series T4900CT User manual

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1.1 Features
The Toshiba T4900CT is one of the lightest and most advanced portable computers available.
Utilizing advanced technology and high-speed components, the T4900CT offers excellent
color display legibility, battery operation, and IBM PC/AT compatibility. The T4900CT
system unit consists of the following features:
❑Microprocessor
The T4900CT uses an Intel PentiumTM Processor (referred to as Pentium in this
manual) that operates at 75 MHz, 3.3 Volts.
❑Math co-processor
The T4900CT has a math co-processor which is stored in the Pentium.
❑Cache memory
The T4900CT has a writeback type 16 KB cache memory which is stored in the
Pentium. The 16 KB cache consists of an 8 KB instruction cache and an 8 KB data
cache.
❑Disk storage
The T4900CT has an internal 2.5-inch 810 MB HDD. A 3.5-inch FDD supports 2 HD
(1.44 MB) floppy disks and 2DD (720 KB) floppy disks.
❑Memory
The T4900CT comes standard with 8 MB of CMOS type Dynamic Random Access
Memory (DRAM) 3.3 Volts. This includes 640 KB of conventional memory and
7,360 KB of extended memory which can be utilized as expanded memory compatible
with the Lotus/Intel/Microsoft Expanded Memory Specifications (LIM-EMS).
❑TFT color LCD
The T4900CT has a high-resolution 10.4-inch full-color, Thin Film Transistor (TFT)
color LCD that displays 640 x 480 pixels.
The T4900CT internal display controller supports VGA functions on the internal
display and SVGA functions on an external display.
❑Keyboard
An easy-to-use 82/84-key enhanced keyboard with full-size keys and standard spacing
is compatible with IBM standard software. The T4900CT’s keybard supports soft-
ware that used a 101/102-key enhanced keyboard.

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❑Batteries
The T4900CT has three different batteries: a main battery, a backup battery, and a
Real Time Clock (RTC) battery.
❑Status indicator panel
The T4900CT has a status indicator panel. It is a liquid crystal display (LCD) panel
which displays a battery charge indicator and 11 icons indicating the system status.
❑Memory card slot
The T4900CT has one optional memory card slot, which enables you to install an
optional memory card.
❑Personal Computer Memory Card International Association (PCMCIA) card slot
The T4900CT has two PCMCIA slots, which enable you to install a MiNC Toshiba
card modem or other industry standard PCMCIA release 2.0 card. These slots are a
type II (5mm) and type III (10.5mm) card thickness.
❑Expansion port
The T4900CT has one unique 150-pin expansion port, which attaches to a Desk
Station IV.
❑RS-232C port
The T4900CT has one 9-pin serial interface port.
❑PRT port
The T4900CT’s Centronics compatible parallel interface port serves two purposes
and can be used to connect a Centronics compatible printer.
❑Mouse port
The T4900CT has one 6-pin mouse port on the back that can be connected to an IBM
PS/2 mouse.
❑Keyboard port
The T4900CT has one 6-pin keyboard port on the back that can be connected to an
IBM PS/2 keyboard.

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❑RGB port
The T4900CT has one 15-pin RGB port on the back that can be connected to an
external video display.
❑Audio ports
•Headphone, standard 3.5 mm diameter miniature stereo jack with speaker shut-off
switch.
•Use a headphone with an impedance of 16W.
•Microphone, standard 3.5 mm diameter miniature monaural jack.
❑Accu point
The T4900CT pointer control stick, located in the center of the keyboard, provides
convenient control of the cursor without requiring desk space for a mouse.

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The T4900CT Personal Computer is shown in figure 1-1. The system configuration is shown
in figure 1-2.
Figure 1-1 T4900CT personal computer
Figure 1-2 T4900CT system unit configuration

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1.2 System Unit Block Diagram
Figure 1-3 is a block diagram of T4900CT system unit.
Figure 1-3 T4900CT system board block diagram

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The T4900CT system board shown in figure 1-3 is composed of the following major compo-
nents:
❑A pentium processor, which incorporates a math co-processor and16 KB cache
memory.
❑The following memory components:
Standard RAM: 8 MB, 64-bit data width (70 ns)
Cache memory: Total 16 KB (inside a Pentium)
System, Video, 128 KB (96 KB are used), 8-bit data width
BIOS: A 1-Mbit flash ROM is used (150 ns).
This ROM contains Initial Reliability Test (IRT), Basic
Input/Output System (BIOS), and video BIOS.
Video RAM: 1 MB, 16-bit data width.
Two 256Kx16 bit chips are used.
Memory card: 4, 8, 16, or 32 MB memory card can be installed.
32-bit data width.
❑Super Integration (SI) T6W23, which stores the following components:
•Two Direct Memory Access Controllers (DMAC): 82C37
•Two Programmable Interrupt Controllers (PIC): 82C59
•One Programmable Interval Timer (PIT): 82C54
•One Floppy Disk Controller (FDC): TC8565
•One Serial Input/Output Controller (SIO): 16550
•One Variable Frequency Oscillator (VFO): TC8568
•One I/O Controller
•One Printer Port Controller
•One Speaker Controller
❑A Real Time Clock (RTC)
One T9934 chip is used. The T9934 has 128 bytes of memory. Fourteen bytes of
memory are used for the calendar and clock. The remaining 114 bytes are used for the
system configuration data.
❑A Keyboard Controller (KBC)
One M37452M4 chip is used. This KBC includes the keyboard scan controller and
keyboard interface controller. The KBC controls the internal keyboard, external
keyboard port, PS/2 mouse port, and pointing stick.
❑VGA display controller: F65545 (208-pin)
3.3 volt operation. This controller controls internal and external VGA compatible
display and external SVGA compatible display with Analog Digital Converter (DAC).
It can display data on the internal and external display at the same time.

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❑Sound Controller
Windows Sound System compatible sound unit is used. One AD1848 chip supports
PCM sound, and YMF262 (OPL3) with YAC512 (DAC) supports FM synthesizer
sound.
❑Clock Generator receives 14.31818 MHz (X1) and generates the following frequen-
cies:
•50 MHz for the CPU (CPU operates 75MHz)
•14.7456 MHz for the COM
•24 MHz for the FDC and VFO
•16 MHz is used for GA
•14.31818 MHz for Video Controller
OSC (X3) generates 32.768 KHz for RTC.
❑Gate Array
System Controller Gate Array
This gate array has the following functions:
•CPU Controller
-SMI Control
-CPU Clock Control
•Memory Controller
-64-bit bus memory control (standard DRAM area)
-32-bit bus memory control (expansion memory area)
•Bus Controller
-64 to/from 32-bit data path width convert
-32-bit local bus control
•Address Latch Controller
-Address convert
-Address Latch
•I/O Register
-Register re-storing for resume
-Special Register
•Processing Speed Controller

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ISA Bus Controller Gate Array
This gate array has the following functions:
•Bus controller
-32 to/from 16-bit bus width convert
-ISA bus interface control
-ISA bus access control
-DMAC control
-DMA address generate
-I/O control
•Memory Controller
-ISA bus interface control
-Refresh address control
•I/O Register
-ISA compatible bus I/O port
-Special Registers
•Suspend/Resume Controller
Sub LCD Controller Gate Array
This gate array has the following functions:
•Status Indicator Panel Controller
-LCD Segment Flashing Controller
•Internal Communication Controller
-KBC/Power Supply (PS) Micro Processor Interrupt Controller
-KBC/PS microprocessor/Main CPU Communication Controller
IC Card Controller Gate Array
This gate array has the following functions:
•IC Card Controller
-PCMCIA IC Card Controller
-Toshiba Modem Card Controller
•EEPROM (for security) Controller
-KBC-Security-EEPROM Communication Controller
•Others
-KBC Communication Controller
-Disable the PRT/FDD Port, HDD Access Controller
-EEPROM (for BIOS) Access Mode Controller
-Sound System Access Controller

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1.3 3.5-inch Floppy Disk Drive
The T4900CT 3.5-inch Floppy Disk Drive (FDD) is a thin, high-performance reliable drive
that supports 720-KB (formatted) 2DD and 1.44-MB (formatted) 2HD 3.5-inch floppy disks.
The T4900CT FDD is shown in figure 1-4. The specifications for the FDD are described in
table 1-1.
Figure 1-4 3.5-inch FDD
Table 1-1 3.5-inch FDD specifications
Item 2-MB mode 1-MB mode
Storage capacity (KB)
Unformatted 2,000 1,000
Formatted 1,475 737
Number of heads 2 2
Number of cylinders 80 80
Access time (ms)
Track to track 3 3
Average 94 94
Head settling time 15 15
Recording track density (tpi) 135 135
Data transfer rate (Kbps) 500 250
Rotation speed (rpm) 300 300
Recording method Modified Frequency Modulation (MFM)

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1.4 2.5-inch Hard Disk Drive
The Hard Disk Drive (HDD) is a random access non-volatile storage device. It has a non-
removable 2.5-inch magnetic disk and mini-winchester type magnetic heads.
T4900CT supports 810 MB HDD. The T4900CT HDD is shown in figure 1-5. Specifica-
tions for the HDD are described in table 1-2.
Figure 1-5 2.5-Inch HDD
Table 1-2 2.5-Inch HDD specifications
810MB
DVAA-2810
Physical specifications
Formatted capacity (MB) 810.0
Disks 3
Heads 6
Cylinders 1,571
Bytes per sector (bps) 512
Cording 1-7RLL
Performance specifications
Access time (average) 14.5
(track to track) 4
Maximum stroke 23.5
Rotation speed (rpm) 3,800
Data transfer rate (Mbps) 24.9 to 36.0
Power requirement
DC voltages (V) +5 only
Power (typical)
Seek (W) 2.8
Read (W) 2.8
Write (W) 2.8
Standby mode
(Spin only) (W) 0.4
Sleep mode
(Motor off) (W) 0.4
Spin-up mode (mA) 940

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1.5 Keyboard
The 82-(USA) or 84-(European) keyboard is mounted on the T4900CT’s system unit. The
keyboard is connected to the keyboard controller on the system board through a 19-pin flat
cable. The keyboard is shown in figure 1-6.
See Appendix F for optional keyboard configurations.
Figure 1-6 Keyboard

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1.6 TFT Color LCD
The TFT Color Liquid Crystal Display (LCD) contains an LCD module, a Fluorescent Lamp
(FL), and an FL inverter board.
1.6.1 TFT Color LCD Module
The T4900CT TFT color LCD supports 640 x 480 pixels with an internal display controller
and 262144 colors for graphics and characters. This controller includes the functions of Video
Graphics Array (VGA) and Super VGA (SVGA) for external display.
The T4900CT’s LCD receives 18-bit data signals, data enable, and shift clock for data trans-
mission. All signals are CMOS-level compatible.
The TFT LCD and FL invertor board are shown in figure 1-7. The specifications for the LCD
are described in table 1-3.
Figure 1-7 TFT color LCD
Table 1-3 TFT color LCD specifications
Item Specifications
Number of dots (dots) 640x480
Dot pitch (mm) 0.33 (W)x0.33 (H)
Display area (mm) 211.2 (W)x158.4 (H)
Contrast 60:1 (minimum)
FL current (mA) 4
FL frequency (KHz) 47

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1.6.2 Fluorescent Lamp (FL) Inverter Board
The FL inverter board supplies high frequency current to light the LCD’s Fluorescent Lamp.
The specifications for the T4900CT’s FL inverter are described in table 1-4.
Table 1-4 FL inverter board specifications
Item Specifications
Input Voltage (VDC) 18
Power (W) 3
Output Voltage (VAC) 1,100
Current (mA) 4.0
Frequency (KHz) 47
Current limits (mA) 2.5 to 4.5

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1.7 Power Supply
The power supply supplies five kinds of voltages to the T4900CT system board. The
T4900CT power supply has one microprocessor and it operates at 500 KHz (power off) or 20
MHz (power on). It contains the following functions:
1. Determines if the AC adapter or battery is connected to the computer.
2. Detects DC output and circuit malfunctions.
3. Controls the speaker and the brightness.
4. Controls the Battery capacity icon, Power on icon, and AC adapter icon on the
status indicator panel.
5. Turns the battery charging system on and off and detects a fully charged battery.
6. Determines if the power can be turned on and off.
7. Provides more accurate detection of a low battery.
8. Calculates the remaining battery capacity.
The power supply output rating is specified in table 1-5.
Table 1-5 Power supply board output rating
DC Regulation Maximum
Use for Name voltage tolerance current Ripple
(V) (%) (mA) (mV)
System logic, FDD, HDD VCC +5 ±5 2,200 100
RS-232C, Flash ROM 12V +12 ±5 120 240
Display DSPV +9.5 to +23 –4.02 W –
RAM, CPU B3V +3.3 ±5 2,200 60
RS-232C M12V –7 to –12.6 – 10 –

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1.8 Batteries
The T4900CT has three types of batteries:
❑Main battery pack
❑Backup battery
❑Real Time Clock (RTC) battery
These batteries’ specifications are described in table 1-6.
Table 1-6 Batteries’ specifications
Battery name Material Output voltage Capacity
Main battery Nickel Metal Hydride 12 V 2,600 mAh
Backup battery Nickel Metal Hydride 7.2 V 35 mAh
RTC battery Lithium-Vanadium 3.0 V 50 mAh
1.8.1 Main Battery
The removable main battery pack is the computer’s main power source when the AC adapter
is not attached. The backup and main battery maintain the state of the computer when you
enable AutoResume.

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1.8.2 Battery Charging Control
Battery charging is controlled by a power supply microprocessor that is mounted on the
power supply. The microprocessor controls whether the charge is on or off and detects a full
charge when the AC adapter and battery are attached to the computer. The system charges
the battery using quick charge or trickle charge.
NOTE: When the temperature difference between the computer and the battery pack is
more than 10°C, a full charge may be detected even if the battery is not fully charged.
Remove the battery pack for about five minutes to let the computer and battery reach the
same temperature. Then, reinstall the battery pack.
❏Quick Battery Charge
When the AC adapter is attached, there are two types of quick charge: quick charge 1
when the system is powered off and quick charge 2 when the system is powered on.
Table 1-7 Time required for quick charges
Kind of battery Charging time
Quick charge 1 Nickel Metal Hydride About 1 hour, 30 minutes
(power off)
Quick charge 2 Nickel Metal Hydride 4 to 6 hours (typical: 5 hours)
(power on)
NOTES 1: The time required for quick charge 2 is affected by the amount of
power the system is consuming. Use of the fluorescent lamp and
frequent disk access diverts power and lengthens the charge time.
2: Using quick charge 1, the power supply microprocessor automatically
stops the charge after two hours and twenty minutes regardless of the
condition of the battery.
If one of the following occurs, the battery quick-charge process stops.
1. The battery becomes fully charged.
2. The AC adapter or battery is removed.
3. The battery or output voltage is abnormal.

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❏Trickle Battery Charge
When the main battery is fully charged and the AC adapter is attached, the micropro-
cessor automatically changes quick charge 1 or 2 to trickle charge.
❏Detection of full charge
A full charge is detected only when the battery is charging at quick charge. A full
charge is detected under any of the following conditions:
1. A battery voltage fall is detected.
2. The charging time exceeds the fixed limit.
3. The thermal rise (+DT) exceeds the fixed limit.
4. The battery’s temperature is over 60°C.
1.8.3 Backup Battery
The backup battery maintains data for AutoResume. The power source used to back-up the
AutoResume data is determined according to the following priority:
AC adapter > Main battery > Backup battery
The backup battery is charged by the main battery or AC adapter when the system power is
turned on and off. Table 1-8 shows the charging time and data preservation period of the
backup battery.
Table 1-8 Backup battery charging/data preservation time
Time
Charging Time Power On 3 H
Power Off 3 H
Data preservation period (full charge) 3 H
1.8.4 RTC battery
The RTC battery provides power to keep the current date, time, and other setup information
in memory while the computer is turned off. Table 1-9 shows the charging time and data
preservation period of the RTC battery.
Table 1-9 RTC battery charging/data preservation time
Time
Charging Time Power On 24 H
Power Off 24 H
Data preservation period (full charge) 1 month

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2.1 Troubleshooting
Chapter 2 describes how to determine if a Field Replaceable Unit (FRU) in the T4900CT is
causing the computer to malfunction. The FRUs covered are:
1. Power Supply Board
2. System Board(s)
3. Floppy Disk Drive
4. Hard Disk Drive
5. Keyboard
6. Display
7. Status Indicator Panel
The Diagnostics Disk operations are described in Chapter 3 and detailed replacement proce-
dures are given in Chapter 4.
The following tools are necessary for implementing the troubleshooting procedures:
1. A T4900CT Diagnostics Disk
2. A Phillips head screwdriver (2 mm)
3. A Toshiba MS-DOS system disk
4. A 2DD or 2HD formatted work disk for floppy disk drive testing
5. A cleaning kit for floppy disk drive troubleshooting
6. A printer port LED
7. An RS-232-C wraparound connector
8. A printer wraparound connector
9. A multimeter
10. An external CRT

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2.2 Troubleshooting Flowchart
Use the flowchart in figure 2-1 as a guide for determining which troubleshooting procedures
to execute. Before going through the flowchart steps, verify the following:
❑Ask the user if a password is registered, and if it is, ask him or her to enter the pass-
word. If the user has forgotten the password, contact your Toshiba representative for
further action.
❑Verify with the customer that Toshiba MS-DOS is installed on the hard disk. Non-
Toshiba operating systems can cause the computer to malfunction.
❑Make sure all optional equipment is disconnected from the computer.
❑Make sure the floppy disk drive is empty.
UPDATE

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Figure 2-1 Troubleshooting flowchart (1/2)