Operating Modes

Figure 2-2. 1/0 Address Space OOOOh

Reserved 0020h

HP-IL Interface 0040h

OOSOh Serial Interface

0060h Timer 1

PPU 0080h

Display Controller OOAOh

Keyboard/Modem Interface OOBOh

OOCOh Timer 2

Plug-In Port 2 OOEOh

Plug-In Port 0100h

Reserved

0400h

I I

Available for plug-in modules

8000h

I I

Configuration EPROM

COOOh

I I

Available for plug-in modules FFFFh

,

2.3 Operating Modes

The computer has several operating modes, which are controlledbya single chip

micro-computer, known as the peripheral processor unit (PPU): The mainframe has two 5 volt supplies, known as VccS and VccDS. These supplies are switched on and off

depending on the mode the mainframe is in. _1~

• Awake Mode: Both 5 volt supplies are on. The display is turned on; the CPU is running or idle. RAM is preserved.

• Sleep Mode: VccS is off (the display is turned off; most circuits are powered down).

VccDS is on but reduced to 3.25 volts nominal (RAM is preserved). The PPU remains in a low power state) monitoring system events. This mode is used to prolong battery life when the computer is not in use.

• Stop Mode: All internal power supplies are turned off. RAM memory is lost. All digital logic in the mainframe) plug-in cards and modem are turned off. This mode isonlyentered if a plug-in card is removed while the mainframe is in Awake Mode.

The following descriptions illustrate the system)s behavior under various conditions.

2.3.1 Sleep Mode

User Initiated sleep mode to remove plug-In module: System is awake; CPU running. User wants to change a plug-in drawer.

Action Required:

User must put system into its sleep mode (by pressing the "Off" softkey in PAM).

System Behavior:

PAM accepts the "Off" command and then issues a sleep command to the PPU.

User removes plug-in drawer. PPU senses the removal and waits until both plug-in drawers are present. During this wait) the PPU keeps updating the real time clock and the battery charge level.

When the user has plugged in both drawers) he must press the @ key to wake the system up. When the system wakes up) power isapplied to the mainframe and both plug-in drawers. The CPU is initially reset. When allowed to run) it reboots.

2

I

Any time a RAM plug-In module Is removed Its contents are lost. You must back up the electronic disc before removing or installing a RAM plug -in module.

User initiated Sleep Mode to conserve battery: System is awake; CPU running.

2 User wants to put system to sleep in order to save power.

Action Required:

User presses the "Off" softkey in PAM.

System Behavior:

The PPU unpowers the CPU and the LCD display. Built-in RAM,

display RAM, and plug-in RAM remain powered. The keyboard continues to be scanned.

System remains in sleep mode until one of the following occurs:

Any key is depressed.

The alarm time is reaphed.

A system interrupt is generated (for example, modem ring detected, serial ring detected, plug-in interrupt detected).

As the system wakes up, the CPU is initially reset. As it begins running, the BIOS determines that the system was in sleep mode (as opposed to a cold start) and restores the system to the state that existed before sleep mode was initiated.

Timeout initiated Sleep Mode to conserve battery: System is awake; CPU is

running. The battery charger is not plugged in. The program running (MS-DOS, PAM, ~

or an application) makes repeated calls to the keyboard driver's status without calling } other I/O drivers. (This occurs when a program is waiting for keyboard input--refer to

"Power-Save Mode" in chapter 10.) System Behavior:

The BIOS monitors I/O driver "call" activity. If the keyboard driver's status is called often enough (with no calls to other I/O device drivers), after the timeout period has expired (set from PAM) the BIOS suspends operation of the current program, does some housekeeping, and then issues the sleep command to the PPU.

The PPU unpowers the CPU and the LCD display. Built-in RAM, display RAM, and plug-in RAM remain powered. The keyboard continues to be scanned.

System remains in sleep mode until one of the following occurs:

Any key is depressed.

The alarm time is reached.

A system interrupt is generated (for example, modem ring detected, serial ring detected, plug-in interrupt detected).

As the system wakes up, the CPU is initially reset. As it begins running, the BIOS ~ determines that the system was in sleep mode (as opposed to a cold start) and , )

r

2.3.2 stop Mode

Situation: System is awake; CPU is running. User removes a plug-in drawer but forgets to put the computer in sleep mode.

System Behavior:

Removal of a plug-in drawer while the system is awake causes the system to enter stop mode. The power supply turns off completely, which turns off all mainframe digital logic and removes power to both plug-in ports. (All built-in RAM, LCD memory, and plug-in RAM data is lost. The real time clock is lost. The battery charge level is lost.)

When both plug-in ports are again occupied, the power supply for the PPU energizes and the PPU is reset.

The PPU waits until the (i) key is pressed before it wakes up the system (by applying power to the mainframe and both plug-in ports). The CPU is initially reset. When allowed to run, it reboots the BIOS (which reinitializes the RAM disk and the real-time clock).

The battery charge level initially reads 0 percent.