Enclosed in the following short article is a short description of the
R65C02 Microprocessor made by Rockwell. For those 8-bitters who are looking
for a cheap upgrade to a PET or those 64/128 owners who want a few extra
commands to their microprocessor. (Note that the pins of an 6502 are not
compatible to a 6510 or an 8502). This information is handed out by
Rockwell and is in the public domain.

[Some important points to keep in mind about the R65C02:

First, this is the microprocessor that's in Schnedler System's TurboMaster.
Schnedler also markets an assembler (MAE64 v5) and a multi-pass symbolic
disassembler (Symbol Master - great product!) that supports the extra
opcodes. For more information on the TurboMaster or the software, contact:

Schnedler Systems
Dept. CIS, 25 Eastwood Rd, P.O. Box 5964
Asheville, NC  28813
(704) 274-4646

Second, it's important to point out that using the extra opcodes in a
program will mean that the program is likely to fail when run on a standard
6502 (or 6510 in the case of the 64). Those opcodes may do nothing in a
6502 or may do something other than what a 65C02 will do.

Third point relates to the second. Any program that uses these opcodes
expecting to run on a 6502 will also yield unpredictable results. Some
games programmers use 6502-bogus opcodes as a protection measure. Most
machine language monitors for 6502's will display unimplemented opcodes as
??? thereby making it tougher for people to figure out the code. Although
this is probably most common in games, I know that PaperClip uses such
codes (unfortunately). There may be other productivity packages that do
too, but PaperClip is the only one I'm sure about.

Fourth, I haven't been able to check this data for accuracy. I presume that
this data has been copied from the Rockwell spec sheet.

- Malcolm 76703,4243]

Features

CMOS silicon gate technology
Low Power (4ma/MHz)
Software compatible with the R6502
Single 5V power supply requirements
Eight bit parallel processing
Decimal and Binary arithmetic
True indexing cabability
Programmable Stack Pointer
Interrupt Capability
Non-maskable interrupt
Direct Memory Access Capability (DMA)
4MHz operating speed


Listing of R65C02 additional opcommands

BBR Branch on Bit Reset
BBS Branch on Bit Set
BRA Branch always
PHX Push X register on stack
PHY Push Y register on stack
PLX Pull X register from stack
PLY Pull Y register from stack
RMB Reset memory bit
SMB Set memory bit
STZ Store Zero
TRB Test and reset bits
TSB Test and set bits

Listing of old opcommands with new address modes

ADC Add memory to accumulator with carry
AND AND memory with accumulator
BIT Test bits in memory with accumulator
CMP Compare memory and accumulator
DEC Decrement memory by 1
EOR Exclusive OR memory with accumultor
INC Increment memory by 1
JMP Jump to a new location
LDA Load accumulator with memory
ORA OR memory with accumulator
STA Store memory with accumulator


OPCODE   Mnemonic  Address      Bytes Cycles

80       BRA       Relative       2     3
DA       PHX       Implied        1     3
5A       PHY       Implied        1     3
FA       PLX       Implied        1     4
7A       PLY       Implied        1     4
9C       STZ       Absolute       3     4
9E       STZ       Absolute,X     3     5
64       STZ       ZeroPage       2     5
74       STZ       ZeroPage,X     2     4
1C       TRB       Absolute       3     6
14       TRB       ZeroPage       2     5
0C       TSB       Absolute       3     6
04       TSB       Zeropage       2     5
0F-7F    BBR       Zeropage       3     5
8F-FF    BBS       Zeropage       3     5
07-77    RMB       ZeroPage       2     5
87-F7    SMB       ZeroPage       2     5

Hex codes for old opcodes with new address

Hex  Mnemonic  New address     Bytes  Cycles
72   ADC       Indirect          2      5
32   AND       Indirect          3      5
3C   BIT       Absolute,X        3      4
34   BIT       Zeropage,X        3      4
89   BIT       Immeadite         2      2
D2   CMP       Indirect          2      5
3A   DEC       Accumulator       1      2
52   EOR       Indirect          2      5
1A   INC       Accumulator       1      2
7C   JMP       Absolute,X        3      6
B2   LDA       Indirect          2      5
12   ORA       Indirect          2      5
F2   SBC       Indirect          3      5
92   STA       Indirect          2      5


New Opcode effects on registers


Opcode         Processor Status Code
.              7 6 5 4 3 2 1 0
.              N V . B D I Z C
BRA
PHX
PHY
PLX            X           X
PLY            X           X
STZ            X           X
TRB                        X
BBR
BBS
RMB
SMB