From: Michael Current (aa700@cleveland.Freenet.Edu)
Date: 04/21/92-07:51:21 PM Z

From: aa700@cleveland.Freenet.Edu (Michael Current)
Subject: Turbo-816
Date: Tue Apr 21 19:51:21 1992

Reprinted from the A.C.E.C. BBS (614)-471-8559

NOTICE: This article originally appeared in the July, 1989 issue of Atari
Interface Magazine and may be freely distributed or reprinted in non-profit
User Group publications as long as the article's author and Atari Interface
Magazine are credited AND this notice is reprinted with the article.  All
other publications must obtain written permission from Unicorn Publications,
3487 Braeburn Circle, Ann Arbor, MI 48108, Phone: (313) 973-8825 before using
this article.

Turbo-Info #1
An Introduction to the Turbo-816
by Chuck Steinman (DataQue)

Welcome to the introductory article in a series which will present the
Turbo-816 from DataQue Software.  Initially, the features of the product will
be presented, and later the series will progress to actual applications and
programming hints.  If you have any comments or critisizms, I would appreciate
it greatly if you would write a note to the editor of this fine magazine and
express your thoughts.

For those of you not familiar with the Turbo-816, it is a hardware and
firmware upgrade for the Atari XL and XE computers that expands the capability
of those machines, while still maintaining compatibility with your existing
software and hardware investment.  There will also be a version for the
original 800, although no release date has been set at this time.  The XL/XE
kit is called the Turbo-816x, and will sell for $120 plus $4.00 S&H within the
US.  Foreign destinations, COD and other special handling would be extra.

The main component of the T816 (short for Turbo-816) is the CPU adapter board.
For those of you unfamiliar with computer jargon, CPU stands for Central
Processing Unit, which is the main "brain" of your computer.  The CPU that
came in your XL/XE computer is an 8bit 6502.  The actual CPU in the Atari
XL/XE computers is a slightly modified version of the 6502.

The T816 adapter board, along with a short ribbon cable, replaces your
existing 6502 CPU with a new, more powerful 16bit CPU.  This new CPU has the
unique capability of also being able to understand the 8bit 6502 CPU
instructions. That allows the adapter board to still execute your original
8bit programs. The CPU adapter board is approximately 5 inches by 2-1/2
inches, and it takes care of all timing and control functions, allowing it to
fully emulate (or function like) the special Atari version of the 6502 while
also extending the addressing range.  One jumper must be added to your Atari
XL/XE motherboard to make the system work.  Installation and modification
information is provided as part of the Turbo-816 kit.

The other component of the Turbo-816 system is the Turbo-OS ROM.  This part is
a 28-pin integrated chip that holds the initialization and control software
that most users take for granted.  Originally, I had planned on this chip
fully replacing the Atari OS and just adding any new functions required by the
new CPU to allow it to work properly.  It wasn't long before I ran into a
snag. Atari would not release the source code for the XL/XE Operating System
ROM to me.  I offered to sign any non-disclosures and pay any required fees,
but the best offer they could come up with was $1000 up front, and 50 cents
per unit sold, for the right to copy only certain sections of the Atari
Operating System ROM, but no source code was to be included in that

I was not impressed with their support, so I proceeded to write the entire
Turbo-OS from scratch.  This not only cost several additional months of
programming effort, but also increased the amount of time to test each and
every function.  The resulting Operating System is 100% compatible with
software that uses the published, legal entry points into the Atari OS and
legal RAM locations.  Because of many programs making illegal calls to the OS
or using reserved RAM, I suggest that BOTH the Atari OS and the Turbo-OS be
installed in your machine and a toggle switch be used to select which is
active.  Details on how to make this modification are also included in the

A popular misconception about the upgrade is that it will execute ST and/or
IBM/PC programs.  It will not.  I have never advertised or claimed it would,
so I can only guess someone that was not familiar with assembly code, or the
internal workings of computers, started this rumor.  The ST uses a 68000
processor, and the IBM uses an 80x86-based processor.  The 65816 is not
software compatible with either of those CPUs, and neither of those CPUs can
directly understand 6502 code.  If someone wants to write such an emulator for
either of those CPUs, let me know when you have it done!

The Turbo-816 uses the WD65C816P5 CPU, which was designed by Western Design
Center and is manufactured by California Microsystems.  This is the same CPU
used in the Apple ][gs.  Anyone familiar with the ][gs knows it is a powerful
little machine, although it does have a few design problems that prevent it
from being able to fully take advantage of the CPU.

Many Atari owners have asked me, "What will this do for me?"  There are many
ways to answer that question depending on what you use your computer for and
whether you program.  The Turbo-816 not only adds 16bit working registers, but
also new, more powerful instructions and a 24bit address bus.  Now with these
new capabilities, more powerful new programs can be written to allow the Atari
computers to compete again with the more expensive 16bit computers.  The new
addressing capability allows for up to 16 megabyte of memory (RAM), and the
new instructions make smaller, faster, and more complex routines possible.

I have made MAC/65 Macros and other information available to all registered
owners via my BBS and the GEnie telecommunications service, allowing owners of
MAC/65, or any other macro assembler, to begin using the new 65816
instructions immediately.

To the non-programmer, at this time there are no programs which take full
advantage of the Turbo-816.  Current applications will run from 5% to over
300% faster depending on how much they use the Turbo-OS.  Since existing
software was not written to access the new memory or take advantage of the new
instructions, that software can only gain performance by calls to the

I will have several new applications which will take advantage of the new
memory and power, though.  The first of these will be a spreadsheet program
called the Turbo-S16.  It will be similar to VisiCalc and SynCalc.  The
program will determine if a Turbo-816 and Turbo-OS are available, and then use
any expanded or explicit memory, if available.  Otherwise, it will run on a
stock Atari 400/800/XL/XE using the normal RAM.  Since it is not initially
going to be designed as a concurrent application (i.e., it will not
multi-task), the program will absorb all available RAM for its use.  That
means, if there is one megabyte of explicit or expanded memory available, the
program will allow you to use up to that amount for the application.  I plan
on releasing this program in ROM, which will be, to my knowledge, the first
spreadsheet program to be implemented in ROM for the Atari.  A discount will
be available (with proof of purchase) to owners of SynCalc, SynCalc+ and
VisiCalc as an incentive to upgrade to the Turbo-S16.  Details will be
released later.

Another application nearing completion is the Turbo-A16.  This is an assembler
that will allow you to assemble native mode 65816 code.  I am trying to
incorporate enough versatility to allow loading of source code from popular
file formats.  That will allow people to use their existing libraries without
first having to convert them.  It has not been decided whether this
application will be in ROM or disk based.

Well, that's the basics of the Turbo-816.  If you have any specific questions
you would like answered, please forward them to the Editor of AIM, and I will
see that you get an answer.  For those of you with GEnie accounts, I have a
special section dedicated for Turbo-816 questions and answers, so feel free to
drop in!

 Michael Current, Cleveland Free-Net 8-bit Atari SIGOp   -->>  go atari8  <<--
   The Cleveland Free-Net Atari SIG is the Central Atari Information Network
      Internet: currentm@carleton.edu / UUCP: ...!umn-cs!ccnfld!currentm
     BITNET: currentm%carleton.edu@{interbit} / Cleveland Free-Net: aa700

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