altered. The A- and X-REGs are altered and the Y-REG is cleared.

Uses: MD1, MD2, MDEND.

Cautions: An exit to location $3F5 is taken if the quotient is less than -2^128 or greater than +2^128-1

Notes: MD2 contains the remainder mantissa (equivalent to the MOD

function). The remainder exponent is the same as the quotient exponent, or 1 less if the dividend mantissa magnitude is less than the divisor mantissa magnitude.

Example: Prior to calling FDIV, FP1 contains -60 (dividend), and FP2 contains +12 (divisor).

 

_____

 

_____

 

_____

 

 

_____

 

 

 

 

 

 

 

FP1:

$85

$80

0

0

(-60)

_____

_____

_____

_____

 

 

X1

 

 

M1

 

 

 

 

 

 

 

 

 

_____

 

_____

 

_____

 

 

_____

 

 

 

 

 

 

 

FP2

$83

$60

0

0

(+12)

_____

_____

_____

_____

 

X1 M1

After calling FMUL, FP1 contains -5 and M2 contains 0.

 

_____

 

_____

 

_____

 

_____

 

 

FP1:

$82

$B0

0

0

(-5)

_____

_____

_____

_____

 

 

X1

 

M1

 

 

 

 

 

FLOAT Subroutine (address $F451)

Purpose: To convert integers to floating point representation.

Entry: A signed (two's complement) 2-byte integer is stored in M1 (high-order byte) and M1+1 (low-order byte). M1+2 must be cleared by user prior to entry.

Uses: NORM1.

Exit: The normalized floating point equivalent is left in FP1. E, FP2, SIGN, and SCR are not disturbed. The A-REG contains a copy of the high-order mantissa byte upon exit but the X- and Y-REGs are not disturbed. The carry is cleared.

Notes: To float a 1-byte integer, place it in M1+1 and clear M1 as well as

Page 74
Image 74
Apple II manual

II specifications

The Apple II, launched in April 1977, was one of the first highly successful mass-produced microcomputer products. It marked a significant leap in personal computing, setting standards for future developments in the industry. Created by Steve Wozniak and Steve Jobs, the Apple II differentiated itself with its user-friendly design, appealing aesthetics, and robust capabilities.

One of the standout features of the Apple II was its open architecture, which allowed users to expand and enhance the computer's functionality. This design enabled hundreds of third-party hardware and software developers to contribute to its ecosystem, resulting in an array of peripherals, including printers, modems, and storage devices. The Apple II utilized a MOS Technology 6502 microprocessor running at a clock speed of 1 MHz. Initially equipped with 4 KB of RAM, the machine could be expanded to 48 KB, accommodating more complex applications and programs.

The Apple II was also notable for its colorful graphics. It was one of the first computers to support color display, offering a 6-color palette with a resolution of 280x192 pixels in 16 colors when using its Color Graphics Card. This feature significantly enhanced the visual appeal of games and educational software developed for the platform, making computing more accessible and entertaining for various audiences.

Apple's commitment to user experience was evident in the design of the machine. It featured an integrated keyboard and a plastic case, which was both durable and visually appealing. The self-contained design included drive bays for floppy disk drives, allowing for quicker data access than traditional tape drives. It also supported audio output, enabling sound effects and music, a novelty at the time.

The introduction of the Apple DOS operating system further underscored the machine's capabilities. DOS streamlined file management and made it easier for users to navigate and manage their data. The combination of hardware and software positioned the Apple II as an educational tool and a gaming platform, fostering a vibrant software ecosystem.

The Apple II family continued to evolve, with variations like the Apple II+, IIe, and IIgs being introduced over the years. These iterations brought enhancements in memory, processing power, and graphics capabilities. The legacy of the Apple II endures, not only as a foundational product in personal computing but also as a symbol of innovation that paved the way for future advancements in technology. Its impact is still felt today, as it inspired countless developers and shaped the trajectory of the computer industry.