Time, Date, Alarms and System Commands

DateMenu

Show a softkey menu for date-related commands, including:

Date
DateTime
DateAdd
DateSub
SetDate
JulianDayNumber
DateFromJulianDayNumber

TimeMenu

Show a softkey menu for time-related commands:

Time
ToHMS
FromHMS
HMSAdd
HMSSub
ChronoTime
Ticks
DateTime
Wait
TimedEval
SetTime

Date format

The date format is YYYYMMDD, with an optional fractional part defining the time, as in YYYYMMDD.HHMMSS.

Note: the date format is intentionally different from the format on the HP-48.

Time format

The time format is HH.MMSS with optional hundredths of a second as in HH.MMSSCC.

SetDate

Set current system date.

The date format is YYYYMMDD, with an optional fractional part defining the time, as in YYYYMMDD.HHMMSS. If the fractional part is zero, then the time is not changed.

Note: the date format is intentionally different from the format on the HP-48.

Date+

Add days to a date. The date format is YYYYMMDD, with an optional fractional part defining the time, as in YYYYMMDD.HHMMSS, and an optional unit, as in YYYMMDD_date. The unit enables special rendering as a date.

For example, to compute the date corresponding to 22222 days in the life of some anonymous programmer, you can use the following code:

19681205 22222 DATE+
@ Expecting Mon 8/Oct/2029

The opposite commands to compute the difference between dates is DDays.

The command accepts the inputs in any order. However, if both inputs can be intepreted as dates, then the first one is a date and the second one a number of days.

SetTime

Set current time from a stack value HH.MMSSCC.

An HMS value can also be given, as returned by the Time command.

→HMS

Convert decimal time to HH.MMSS (Hours, Minutes, Seconds) format.

For example, twelve hours and a half are converted to twelve hours and thirty minutes as follows:

12.5 →HMS
@ Expecting 12:30:00

HMS→

Convert time in HH.MMSS (Hours, Minutes, Seconds) format to numerical time.

DB48x converts the time as a fraction to keep the result exact:

12.30 HMS→
@ Expecting 12 ¹/₂

HMS+

Add time in HH.MMSS format.

10.30 2.40 HMS+
@ Expecting 13:10:00

HMS-

Subtract time in HH.MMSS format

10.30 2.40 HMS-
@ Expecting 7:50:00

→DMS

Convert value to DMS format.

The →DMS command converts a decimal value to DMS (Degrees, Minutes, Seconds) format. The input is interpreted as decimal degrees and converted to the DMS format. The result is returned as a unit object with the _dms unit.

12.5 →DMS
@ Expecting 12°30′00″

DMS→

Convert value from DMS format.

The DMS→ command converts a DMS (Degrees, Minutes, Seconds) value to decimal format. The input can be a unit object with the _dms unit. The result is returned as a decimal value representing degrees.

12.30 DMS→
@ Expecting 12 ¹/₂

Ticks

Return system clock in milliseconds

TEVAL

Perform EVAL and measure elapsed time

Date

Return the current system date as a unit object in the form YYYYMMDD_date. This displays on the stack according to date format settings, in a way similar to what is shown in the header, e.g. 23/Feb/2024 or 2024-02-23.

DateTime

DDays

Number of days between dates.

To compute the number of days in 2024, use:

20250101 20240101 DDAYS
@ Expecting 366 d

Time

Return the current system time as a unit object in the form HH.MMSS_hms. This displays on the stack as HH:MM:SS.

JulianDayNumber

Return the Julian day number for the given date and time.

For dates the Gregorian calendar is assumed. The Gregorian calendar jumps from 1582-10-04 to 1582-10-15. This command ignores that gap, so the Julian day number given by this command for dates on or before 1582-10-14 may deviate from other converters like The NASA Julian Date/Time Converter.

To compute the Julian Day Number for the first day of the millenium:

20000101 JDN
@ Expecting 2 451 545

Datefromjuliandaynumber

Return the date for a given Julian day number.

This command converts a Julian day number to a date in the Gregorian calendar. It is the opposite of the JDN command.

2451545 JDN→
@ Expecting Sat 1/Jan/2000

ACK

Acknowledge oldest alarm (dismiss)

ACKALL

Acknowledge (dismiss) all alarms

RCLALARM

Recall specified alarm

STOALARM

Create a new alarm

DELALARM

Delete an existing alarm

FINDALARM

Get first alarm due after the given time

Version

Return DB48X version information as text.

▶ "Version information"

Chuck

The most powerful command in DB48x.

▶ "Chuck pearl of wisdom"

The CHUCK command is by far the most powerful command in DB48x. Users must run it regularly to keep their calculator in shape.

CHUCK does not have arguments, it wins every single one.
CHUCK does not merely produce a result, it produces the best result every single time, effortlessly.
CHUCK does not need help, it provides help.
CHUCK never fails, any error is a user error.
CHUCK does not drain the battery, it exercises power.
CHUCK is so fast it has to slow down for you to keep up.
CHUCK can identify if your DB48x build is genuine.

FreeMemory

Return the number of bytes immediately available in memory, without performing a cleanup of temporary values (garbage collection).

AvailableMemory

Return the number of bytes available in memory.

Remark: The number returned is only a rough indicator of usable memory. In particular, recovery features consume or release varying amounts of memory with each operation.

Before it can assess the amount of memory available, AvailableMemory removes objects in temporary memory that are no longer being used. Like on the HP48, you can therfore use MEM DROP to force garbage collection. However, there is also a dedicated command for that, GarbageCollect.

GarbageCollect

Perform a clean-up of temporary objects and return number of bytes reclaimed.

In order to speed up normal operations, temporaries are only discarded when necessary to make room. This clean-up process, also called garbage collection, occurs automatically when memory is full. Since garbage collection can slow down calculator operation at undesired times, you can force it to occur at a desired time by executing GarbageCollect.

GarbageCollectorStatistics

Return an array containing garbage collector statistics, including:

The number of garbage collection cycles
The total number of bytes collected
The total time spent collecting garbage
The number of bytes collected during the last collection cycle
The duration of the last collection cycle
The number of bytes cleared by temporaries cleaning

RuntimeStatistics

Return an array containing runtime statistics, including:

The time spent running (i.e. the calculator is in high-power state)
The time spent sleeping (i.e. the calculator is in low-power state)
The number of times the calculator entered high-power state

Note that the calculator tends to spend more time in active state when on USB power, because of additional animations or more expensive graphical rendering.

Bytes

Return the size of the object and a hash of its value. On classic RPL systems, the hash is a 5-nibbles CRC32. On DB48X, the hash is a based integer of the current wordsize corresponding to the binary representation of the object.

For example, the integer 7 hash will be in the form #7xx, where 7 is the value of the integer, and xx represents the integer type, as returned by the Type command.

X ▶ Hash Size

Type

Return the type of the object as a numerical value. The value is not guaranteed to be portable across versions of DB48X (and pretty much is guarantteed to not be portable at the current stage of development).

HP-compatible types

If the CompatibleTypes setting is active, the returned value roughly matches the value returned by the HP50G. It always returns 29 for arrays, not 3 (real array) nor 4 (complex array). It returns 1 for both polar and rectangular complex numbers, irrespective of their precision. 128-bit decimal values return 21 (extended real), 32-bit and 64-bit return 0 (real number). The separation between 18 (built-in function) and 19 (built-in command) may not be accurate.

The values returned by Type in HP-compatible mode are as follows:

0: Real number
1: Complex number
2: Text (called character string in HP manuals)
3: Real array (DB48x returns 29)
4: Complex array (DB48x returns 29)
5: List
6: Global name
7: Local name
8: Program
9: Expression
10: Based integer (binary integer in HP manuals)
11: Graphic object
12: Tagged object
13: Unit object
14: Library reference (XLIB name)
15: Directory
16: Library (not on DB48x)
17: Backup object (not on DB48x)
18: Built-in function (DB48x returns 19)
19: Built-in command
20: System binary (not on DB48x)
21: Extended real (DB48x returns 0)
22: Extended complex (DB48x returns 1)
23: Linked array (not on DB48x)
24: Character (not on DB48x)
25: Code object (not on DB48x)
26: Library data (not on DB48x)
27: Mini font (dense font on DB48x)
28: Real integer
29: Symbolic vector/matrix (all arrays on DB48x)
30: Font (sparse fonts on DB48x)
31: Extended object (not on DB48x)

DB48x detailed types

If the DetailedTypes setting is active, the return value is negative, and matches the internal representation precisely. For example, distinct values will be returned for fractions and expressions.

Note The TypeName command returns the type as text, and this is less likely to change from one release to the next. DB48X-only code should favor the use of TypeName, both for portability and readability.

The values returned by Type are negative, beginning at -2, in the order shown in the table for TypeName below. Commands each have their individual type number. Returned values are not guaranteed from release to release, and they may differ depending on build options or hardware platform (e.g. the values on DM32 or DM42) may differ. The values for data types are not necessarily contiguous either. For example, the Type for a tagged object may be -1473 on version 0.9.1, and may change over time (the reason being that rarely used types have a two-byte type prefix).

Use TypeName for portability.

TypeName

Return the type of the object as text. For example:

12 typename`
@ Expecting "integer"

The values returned by Type in detailed mode are as follows, where the spelling is what TypeName returns:

directory
text
list
program
block (unquoted code block)
locals (local variables structure)
expression
funcall (function call in expression, e.g. F(1;2;3)
local (local variable name)
symbol (global variable name)
equation (reference to equation library, e.g. ⒺSimple Shear)
xlib (reference to library, e.g. ⓁDedicace)
array
menu
unit (e.g. 1_km)
assignment (e.g. X=3)
rectangular (complex numbers such as 2+3ⅈ)
polar (complex numbers such as 2∡30°)

hex_integer (based number with enforced base 16)
dec_integer (based number with enforced base 10)
oct_integer (based number with enforced base 8)
bin_integer (based number with enforced base 2)

based_integer (based number with current base)

hex_bignum (large based number with enforced base 16)
dec_bignum (large based number with enforced base 10)
oct_bignum (large based number with enforced base 8)
bin_bignum (large based number with enforced base 2)

based_bignum (large based number with current base)
bignum (large integer, typically more than 64 bits)
neg_bignum (negative large integer)
integer (typically for integers where value takes less than 64 bits)
neg_integer (negative small integer)
fraction
neg_fraction
big_fraction
neg_big_fraction
hwfloat (hardware-accelerated 32-bit binary floating point)
hwdouble (hardware-accelerated 64-bit binary floating point)
decimal (variable precision decimal)
neg_decimal (variable precision negative decimal)
comment
grob (HP-compatible graphic object)
bitmap (hardware-optimized bitmap)
Drop (commands have their name as type name)
font
dense_font
sparse_font
dmcp_font
tag
polynomial
standard_uncertainty
relative_uncertainty

PEEK

Low-level read memory address

POKE

Low level write to memory address

NEWOB

Make a new copy of the given object

USBFWUPDATE

PowerOff

Turn calculator off programmatically

SystemSetup

Display the built-in system setup

SaveState

Save the machine's state to disk, using the current state if one was previously loaded. This is intended to quickly save the state for example before a system upgrade.

ScreenCapture

Capture the current state of the screen in a dated file stored on the flash storage under the SCREENS/ directory. This is activated by holding 🟨 and O simultaneously. Pressing the keys one after another activates the DisplayMenu.

BatteryVoltage

Return the current battery voltage as a decimal value.

USBPowered

Returns True if the calculator is connected to USB power.

Programmers can use this command in a long-running program to alter the frequency of power-hungry operations such as displaying on the screen.

For example, the CollatzConjecture library program only displays the amount of memory used when powered by USB:

ⓁCollatzBenchmark

LowBattery

Returns True if the calculator is running low on battery, which is defined as having less than 1/4th of the charge between 3000 mV and the value defined in MinimumBatteryVoltage.

Programmers can use this command in long-running programs to automatically pause their programs in order to avoid draining the battery and losing memory.

DMCPLowBattery

Returns True if the calculator is running low on battery according to the DMCP get_lowbat_state() function. Experimentally, this function is not very reliable in detecting low-battery conditions. Use LowBattery instead.

MinimumBatteryVoltage

This setting defines the minimum battery voltage in millivolts where the calculator will automatically switch off to preserve battery. The default value is 2600mV, which appears to be safe even with no-brand batteries.

Experimentally, the DM42 can operate at much lower voltages than 2.4V, but some operations become unreliable or even cause a reset. Notably, the calculator may not be able to wake up without rebooting, losing user data in the process.

If the battery goes below MinimumBatteryVoltage, the calculator will automatically switch off with a message on the screen requesting to connect to USB power or to change the battery. Selecting a higher value than the default can be used to have an early reminder that you need to purchase replacement batteries.

BatteryRefresh

This setting defines the refresh interval in milliseconds between checks or updates of the battery levels. The default is 5000 (5 seconds).

Note that explicitly calling BatteryVoltage, USBPowered or LowBattery causes the corresponding values to be immediatley refreshed, but does not necessarily cause the battery status on screen to update.

DMCPDisplayRefresh

On hardware calculators, use the DMCP system background display refresh. This is the default setting, and presumably should use less energy.

SoftwareDisplayRefresh

On hardware calculator, use the software display refresh. This should be used for debugging purpose only.

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