1FEE 60

RTRN RTS

RETURN

 

END

 

***************************************************************************

Dr. Dobb's Journal, November/December 1976, page 57.

ERRATA FOR RANKIN'S 6502

FLOATING POINT ROUTINES

Sept. 22, 1976

Dear Jim,

Subsequent to the publication of "Floating Point

Routines for the 6502" (Vol.1, No.7) an error which I made in the LOG routine came to light which causes improper results if the argument is less than 1. The following changes will correct the error.

1.

After:

 

 

CONT JSR

SWAP (1D07)

 

Add:

A2

00

LDX

=0

LOAD X FOR HIGH BYTE OF EXPONENT

2.

After:

 

 

STA

M1+1 (1D12)

 

Delete:

 

 

LDA

=0

 

 

 

 

 

STA

M1

 

 

Add:

10

01

BPL

*+3

IS EXPONENT NEGATIVE

 

 

CA

 

DEX

 

YES, SET X TO $FF

 

 

86

09

STX

M1

SET UPPER BYTE OF EXPONENT

3.Changes 1 and 2 shift the code by 3 bytes so add 3 to the addresses of the constants LN10 through MHLF whenever

they are referenced. For example the address of LN10 changes from 1DCD to 1DD0. Note also that the entry point for LOG10 becomes 1DBF. The routines stays within the page

and hence the following routines (EXP etc.) are not affected.

Yours truly,

Roy Rankin

Dep. of Mech. Eng.

Stanford University

Page 89 Page 91
Page 90
Image 90
Apple II manual Errata for Rankins Floating Point Routines, LDX Load X for High Byte of Exponent, Lda Sta
Page 89 Page 91

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.
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