Apple II Plus
Source: Wikipedia

Apple II Plus

The Apple II Plus, introduced in June 1979, included the Applesoft BASIC programming language in ROM. This Microsoft-authored dialect of BASIC, which was previously available as an upgrade, supported floating-point arithmetic, and became the standard BASIC dialect on the Apple II series. It shipped with 16 KB, 32 KB or 48 KB of main RAM, expandable to 64 KB by means of the Language Card, an expansion card that could be installed in the computer’s slot 0. The Apple’s 6502 microprocessor could support a maximum of 64 KB of address space, and a machine with 48KB RAM reached this limit because of the additional 12 KB of read-only memory and 4 KB of I/O addresses. For this reason, the extra RAM in the language card was bank-switched over the machine’s built-in ROM, allowing code loaded into the additional memory to be used as if it actually were ROM. Users could thus load Integer BASIC into the language card from disk and switch between the Integer and Applesoft dialects of BASIC with DOS 3.3’s INT and FP commands just as if they had the BASIC ROM expansion card. Like the Apple II, the Apple II Plus had no lowercase functionality. All letters from the keyboard were upper-case, there was no caps lock key, and there were no lowercase letters in the text-mode font stored in the computer’s ROM.

History of Apple II Plus is provided by wikipedia 
Apple II Plus
Source: apple2online – Apple II Plus

Apple II Plus – General information

Overview
IntroducedJune 1979
DiscontinuedDecember 1982
Order NumberA2S1016 (16 KB memory)
A2S1032 (32 KB memory)
A2S1048 (48 KB memory)
Price$1,195 (with 16 KB memory)
$1,295 (with 48 KB memory)
$1,395 (with 48 KB memory)
ColorsBeige
Weight11.5 Ibs.
5.21 KG
Dimensions4.25” H x 15.25” W x 18” D
10.79 cm H x 38.73 cm W x 45.72 cm D
Hardware
ProcessorMOS Technology 6502
Speed1 MHz
Architecture8-bit
Number of Cores1
System Bus1 MHz
StorageNone
Built-in MemoryNone
Maximum Memory48 KB or 64 KB witch Language Card
Memory Slots24 sockets in 3 rows for 16-pin 4 KB (4096, 2104 type)
or 16 KB (4116, 2116 type) modules
Memory minimum speed350 ns
ROM12 KB
Software
SoftwareApple DOS 3.2 (initially optional; later included)
FirmwareApplesoft BASIC
Connections
Cassette1 – in
1 – out at 1500 bps
Game1 – internal 16-pin GAME I/O
Display Connection1 – RCA composite positive video
Display1 – RCA for composite video output
(Display resolution 40 x 48 – 16 colors or 280 x 192 – 6 colors)
Text Display40 characters per row (max. 24 rows)
Audio Out1 – Built-in 8 ohm speaker
Expansion Slots8 – 50-pin Apple II peripheral
Accesories
KeyboardBuilt-in 52-key uppercase keyboard
MediaOptional Cassette Interface or Disk II floppy drive
Power
Line Voltage110 or 110/220V AC

Source: Wikipediaapple2onlineApple

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