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Article #74 (74 is last):
Subject: Turbo816 / hardware
Posted-By: xx004 (aa700 - Michael Current)
Edited-By: xx004 (aa700 - Michael Current)
Date: Mon Apr 12 21:02:06 1993

The Turbo816 is a 65816 microprocessor that runs at the normal clock speed
of the computer.  It's meant to be installed in a XL/XE machine, and comes 
with a replacement OS.  The card measures about 3.5x7", roughly the size
of two 3.5" disks end to end.  On end is a 40 pin ribbon cable which plugs
into the 6502 socket on the motherboard.  On the end is a 50 pin connector
for attaching Turbo-BUS cards, like SRAM memory, PROM application cards,
hardware interface cards, blah blah.

The 65816 has two operating modes, emulation mode, and native mode.
In emulation mode, the chip acts mostly like a 6502, but more OPCODES 
are available, as if you had something more than a 65C02 in your machine.
See the MAC/65 manual on 65C02 opcodes for more details.

In native mode, you can set the accumulator, x and y register to 16 bits.
Two separate registers the data bank register and program bank register,
let you do 24 bit addressing.  The Turbo-BUS, the 50 pin connector, provides
all 24 address pins and 8 data pins, for a 16 megabyte LINEAR addressing space.

new opcodes include program counter relative addressing for true relocatable
code, data block move commands, new addressing modes, and the ability to 
move page zero, now called the direct page, to anywhere in the first 
64K of address space.  

The Operating System, called the Turbo-OS by Dataque software, is a rewritten
version of the XL operating system with additions.  These include a callable
menu which lets you test your internal hardware, examine any and all memory,
determine which and how memory memory is available, and call Turbo-Apps which
have been initialized from their PROM cards.  There are also some memory
management routines in the OS and some other nifty routines callable from
software written explicitly for it.

The  OS does have some timing problems however, and the 65816 does not
in some cases execute 6502 OPCODES in the same number of cycles as the 
true 6502 does.  The combination, plus another problem inherant in the
earlier 65816 chips causes some compatibility problems.

It's been reported that the Black Box didn't work with the T-816, and I 
had personal problems with both a MIO and a Newell 1088K upgrade with
the T816.  

Dataque provides SRAM cards, in several configurations, including 64K and
256K.  Dataque also had the Turboclock, which was a 32K SRAM, and 32K PROM
card with a battery backed, Dallas Semiconductor real time clock.  
A clock program was callable from the OS-Menu which would set the Dallas
clock, or read the Dallas clock and set the SpartaDOS clock.  These routines
were also callable from software.

Dataque also provides a 65816 assembler , and a beta 65816 debugger.
No high level language is available for the Atari 65816.
THe only application seen for the 65816 is Turbocalc from Dataque.
This is a rewritten version of Speedcalc from Byte, on cartridge.  
The spreadsheet will run on either stock or 65816 computers.
If a 65816 is running with a memory card, the largest contigous block of
RAM was usable by the spreadsheet.  I had a 256K card, plus the 
CLock card with 32K or RAM.  THe Spreadsheet make the 256K available to itself
for spreadsheet use.  THe spreadsheet was good, I liked the drop down menus,
but there were some routines that were buggy.  The move data routine was 
buggy.  You had to be careful how you used it, and only move or copy cells
to other empty cells.  Moving or copying cells on top of other filled
cells resulted in spreadsheet corruption.

The fact that RAM was only expandable via SRAM was a problem.
SRAM is physically larger than DRAM, and more expensive.  It is impossible
to fit the T816 card and any RAM  card into a XL/XE except the 1200XL.
Wiring up a 4 meg or 1 meg SIMM would have been more useful.  I think
it could be done personally.  Bob Woolley had some 1200XL schematics where
he used just the REF and CAS signals from the ANTIC chip to enable 
automatic refresh mode in a 1 meg  SIMM for a 1024K XE type upgrade.
These same signals should be somehow usable in wiring up a SIMM that was
addressed through the 65816, since the 65816 is still wired up 
in SYNC with the ANTIC.

The T816 has POTENTIAL.. look at the Apple IIgs crowd, but the lack of 
smaller, cheaper RAM, real applications, and a high level programming language
like BASIC, C, or Action!/816 prevented the 816 from becoming anything more
than a hardware hacker's toy.  Mine has been unused for years.  I put over 
$400 into all the goods, and haven't got any honest use out of it.  Truly
one of my worst 8 bit purchase decisions.  Nevertheless, I still dream about
someday putting it in a 1200XL and finding time to program my own stuff for

Jeff McWilliams  EE Engineer --> Michigan Tech. 
The Minstrel Boy to the war is gone,
      In the ranks of death you'll find him;
His father's sword he has girded on,
      And his wild harp slung behind him.    Thomas Moore

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