Re: Enhanced //e with a 6503??!

[heuser.marcus@freenet.de]

> Hang on, you have it backwards.
>
> The standard 65C02 was made by Western Design Center and second sourced
> by companies like GTE. It does NOT contain the bit manipulation
> instructions you mention.

Thanks for the clarification!

> Rockwell's version of the 65C02 (R65C02) adds the extra BBR, BBS, RMB
> and SMB instructions (all of the x3, x7, xB and xF opcodes). In a
> "normal" 65C02, these opcodes are all NOPs.

The "Programming the 6502" by Zaks I have (9th German edition) doesn't
differentiate between the 65C02 and the R65C02! And I thought I found
all errors in this volume...

> The same opcodes were reused on the 65802/65816 for completely different
> functions, so if any code attempts to use these opcodes to take
> advantage of the Rockwell R65C02 then it will probably crash on a IIgs,
> unless it uses some special code to be certain it is running on a
> R65C02.

The book states that the SC02 is upward compatible with the 16 bit CPUs
- at least they got this one right...

> Similarly, code which attempts to use 65802/65816 instructions has to be
> very careful to check that is actually running on one of these
> processors and not a 6502, 65C02 or R65C02.

I see: The 65SC02 and the WDC 65C02 are the same and we have the
Rockwell R65C02 as the third variant to check (if we want to use these
special bit instructions).

> "Programming the 65816 et. al." by Eyes & Lichty had a routine to
> distinguish between a 65816/65802, 65C02 and 6502, but it didn't allow
> for the R65C02. I managed to come up with an extension to this function
> to also check for an R65C02.

Do you see a chance of posting this routine?
If not - don't worry: Your posting already is a gold mine!

> A "Platinum IIe" I have here has a G65SC02 (presumably GTE),

I have two SC02 flying around here - one from GTE (which goes by the
name you write) and the other from CMD.

> which will be fully compatible with the standard WD65C02.

Always thought that they were inferior because of the missing
instructions (which I wouldn't use anyway ;-)

Now for the bonus question:

Is the 338-6503 from Rockwell now 100% compatible to the WDC 65C02 or
an Rockwell R65C02 with the extended instructions?

;o)

bye
Marcus