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Introduced June 1979
Discontinued January 1983
Release Price     $1195

 

        The Apple II Plus is an upgraded version of Apple's first mass produced computer the Apple II. It was released approximately 2 years after the release of the Apple II in June of 1979. The computer is actually the same as it's predecessor with a few 'enhancements'.

      One improvement was the amount of RAM on the system board. It came standard with 48 kilobytes of RAM, on the mother board, and could be expanded to a full 64 kilobytes by inserting a 16 kilobyte expansion card into slot 0 and using a bank switching technique to trick the MOS Technology 6502 processor into seeing it. 

      This was necessary because the 6502 processor is an 8 bit chip with only 16 address lines which limits it to be able to address only 65,536 (64k)address locations. And since the Apple II Plus uses 16 kilobytes of those locations to store it's ROM instructions, only 48 kilobytes of space is left for RAM usage. But the engineers at Apple came up with this neat little trick of swapping 16k blocks of RAM into the address area reserved for ROM as needed to give the illusion that there is a full 64k of RAM available for programming.

      The ROM was rewritten and gone was the hand assembled BASIC written by the man who invented the Apple II, Steve Wozniak, replaced with a new integer BASIC written by a small software company owned by..... [ you hard core Apple types should look away now :-) ] ...Bill Gates. An auto-starting routine was added to the ROM to speed up booting and a spring was put under the reset key to solve that little problem that must have annoyed the early Apple users who would accidentally hit the reset key and lose hours of typed work.

      This Apple II Plus is one of two working models I have in my museum. I was able to put them together from three broken ones and some spare parts acquired from Ebay auctions. I would like to thank Brandon Cobb, Ron Watson, and Robert Ackermann for their contributions to this exhibit.

 

System Architecture Ports Data Storage
Processor: MOS Technology  6502
PMMU: n/a
FPU: n/a
Data Buss: 8 bits
Address Buss: 16 bits
L1 Cache: n/a
L2 Cache: n/a
2nd Processor: n/a
No. of Expansion Slots: 8
Clock Speed: 1.023 MHz
Buss Type: Apple Proprietary
   
USB: n/a
ADB: n/a
Video: 1 RCA
Floppy: n/a
SCSI: n/a
Geoports: n/a
Ethernet: n/a
FireWire: n/a
Mic Type: n/a
AirPort Ready: n/a
Other Ports:  Int Game
Tape Drive: Standard
Disk Drive: Optional
Floppy Size: 5 1/4 inch
No. of FD's:: up to 2
Int Hard Drive: none
Int HD Size: n/a
Int HD Interface: n/a
Int CD Support: n/a
Orig CD Speed: n/a
No. of Internl Bays: none
Memory Video and Graphics
Logic Board: 4K or 16K
RAM Slots or Sockets: 24 (3 Banks of 8 sockets)
Min - Max RAM: 4K - 48K (64K using plug in board)
Min RAM Speed: 200 ns Dynamic RAM
RAM Sizes:  
Install in Groups of: 8 - 16 Pin DIP Memory Chips
Notes: Uses TMS4116-20 chips for 16K to 64K
   
Graphics Processor uses CPU
Screen size - columns & rows 40 x 24
Video on board yes
Video RAM Shares Logic Board RAM
Max colors 16
RGB output no
Composit Video Output yes
Screen Resolution 280 x 192
Physical Specs. Software Power
Introduced: January 1977
Discontinued: June 1979
Form Factor: Apple II
Gestalt ID: n/a
Weight (lbs): 11.5
Dimensions (in): 4.25 H x 15.25 W x 17.75 D
Notes:  
Addressing Modes: 8 bit
Orig SSW: Integer Basic
Orig Enabler: n/a
ROM ID: n/a
ROM Ver: n/a
ROM Size: 16K
AppleTalk Ver: n/a
Mac OS Supported: n/a
Max Watts: 60
Amps:  
BTU per Hr:  
Voltage: 120
Freq Range: 60 Hz
Battery Type: n/a
Soft Power: n/a
Pass Through: no
Sound Keyboard Specs.  
Sound Interface Device: uses CPU
Sound Generation: tone output to speaker
ADSR Capable: no
Sound Output: internal speaker only
Sound Input: no
Notes:  
   
Number of keys: 52 full stroke
Built In: yes
Detached: no
Upper / Lower case yes / yes