Thank you for the correction, Gornopos.
Back in the 1980s when I was with First Star and even before when I was in High School (BTHS), the arguments over the 6502 unsupported opcodes were rampant. These Opcodes were, well, different per manufacturer, as a few did try to correct them and even make them standard. But others either left them (Like MOS under Commodore) or turned them into NOPs (No Operation for 1 clock cycle)
Since the 1980s video game arena was with the top 3 (in the USA) = Apple / Atari /Commodore, these three were 6502 based machines, we programmers then would argue which machine code routine would be best as in theory, but it always did not work as because of the support chips to the 6502 were different and the system's Kernel ROMs were also different. An example is my Universal Joystick Routine - before then programmers would write the joystick program and then fit the program to it. This often ballooned a small game program into a big one. But I wrote a small subroutine there the joystick was read and direction determined before the game can process the input into its actions. This kept game programs small. And it was great for the Atari and Commodore though minor programming was needed or the fire button, at lest 90% of the routine was kept. But with Apple using analog joysticks the whole routine had to be rewritten to handle analog inputs and fire buttons presses (Apple had 2, Commodore/Atari had 1). So what turned out as a simple program subroutine for two machines was complicated for the third because of hardware differences.
On top of all that, some programmers used unsupported opcodes in their programs, which sometimes worked for the mass market and sometimes did not. We were looking for ways to shorten programs because at the time, all programs had to fit with 16K of RAM Space (expect for the Vic20, and for that it was either 8K or even down to its bare minimum of 4K).
Other machines like the RadioShack/Tandy Coco (6809 based, where the 6502 branched of the 6800 years before in the 1970s), Coleco and video game consoles like the Atari 2600 and Sege Game System
Here's a couple links of unsupported op codes, though it incomplete, and does not account for all the 6502s made.
http://bbc.nvg.org/doc/6502OpList.txt
http://visual6502.org/wiki/index.php?title=6502_Unsupported_Opcodes
(one really strange opcode in detail) http://visual6502.org/wiki/index.php?title=6502_Opcode_8B_(XAA,_ANE)
In large or repeating programs and even that (stupid) French Silk 6502 Assembler when it compiles, I noticed that that takes a minute to do on the 6502, took 58 seconds on the 65C02. Though this is not much in terms of performance, overall it was a big step in performance as it builds up over time. For me in those days was to run (or compile since that took a long time to do) a program for a couple of hours and see where it is at the end of time. In this the 65C02 was way ahead of the 6502. And the answer is simple - Being a CMOS processor, the 65C02 has a thinner silicon matrix and less resistance with that matrix. This gives is a faster processing speed on the nano-second level. Given time, nano-seconds adds up to microseconds and microseconds adds up to full seconds. But in today's world, who is going to worry about a couple nano-seconds? Back in the 1980s it was a necessity.
- - - - (Back to subject)
If the IIgs ROM 0 is gold because of people upgrading them, I need to test out my IIgs-Woz as it was given to me as a ROM 0. Whether it was updated over the years remain to be seem. I'm not even sure if it can turn on as the last time it was turned on was over 20 years ago. It might need a recapping of those two large caps that Uniserver mentioned needs recapping on the IIgs.
I'm not looking for a machine that runs GSOS though it would be nice to have.
But compared to a IIe, it depends on the IIe. If Joad has a not-upgraded IIe from 1982, it would be more valuable than the IIgs or IIc. This particular IIe would be better to own as a collector's item. If the ROM and CPU has been upgraded, then its value drops as a collector's piece. But like I believe you stated, what is the machine needed for - as a daily driver or as a museum piece?
A IIc is nice, but its not the perfect machine. Unless its a Rev 2 or 3 or it is a IIc+, it can not be upgraded. And those that can, only the memory can be upgraded. The Laser 128 (VTec's IIc Clone) has a slot on the side of the case to add a standard Apple II card to. On top of everything else the IIc has plus it has a Turbo Mode which the runs the CPU at 2Mhz (or 4MHz) which the IIc does not unless you put in a Rocket Chip or Zip Chip into the IIc! These accelerators alone are in the $500 range on ebay.
Back in the 1980s when I was with First Star and even before when I was in High School (BTHS), the arguments over the 6502 unsupported opcodes were rampant. These Opcodes were, well, different per manufacturer, as a few did try to correct them and even make them standard. But others either left them (Like MOS under Commodore) or turned them into NOPs (No Operation for 1 clock cycle)
Since the 1980s video game arena was with the top 3 (in the USA) = Apple / Atari /Commodore, these three were 6502 based machines, we programmers then would argue which machine code routine would be best as in theory, but it always did not work as because of the support chips to the 6502 were different and the system's Kernel ROMs were also different. An example is my Universal Joystick Routine - before then programmers would write the joystick program and then fit the program to it. This often ballooned a small game program into a big one. But I wrote a small subroutine there the joystick was read and direction determined before the game can process the input into its actions. This kept game programs small. And it was great for the Atari and Commodore though minor programming was needed or the fire button, at lest 90% of the routine was kept. But with Apple using analog joysticks the whole routine had to be rewritten to handle analog inputs and fire buttons presses (Apple had 2, Commodore/Atari had 1). So what turned out as a simple program subroutine for two machines was complicated for the third because of hardware differences.
On top of all that, some programmers used unsupported opcodes in their programs, which sometimes worked for the mass market and sometimes did not. We were looking for ways to shorten programs because at the time, all programs had to fit with 16K of RAM Space (expect for the Vic20, and for that it was either 8K or even down to its bare minimum of 4K).
Other machines like the RadioShack/Tandy Coco (6809 based, where the 6502 branched of the 6800 years before in the 1970s), Coleco and video game consoles like the Atari 2600 and Sege Game System
Here's a couple links of unsupported op codes, though it incomplete, and does not account for all the 6502s made.
http://bbc.nvg.org/doc/6502OpList.txt
http://visual6502.org/wiki/index.php?title=6502_Unsupported_Opcodes
(one really strange opcode in detail) http://visual6502.org/wiki/index.php?title=6502_Opcode_8B_(XAA,_ANE)
In large or repeating programs and even that (stupid) French Silk 6502 Assembler when it compiles, I noticed that that takes a minute to do on the 6502, took 58 seconds on the 65C02. Though this is not much in terms of performance, overall it was a big step in performance as it builds up over time. For me in those days was to run (or compile since that took a long time to do) a program for a couple of hours and see where it is at the end of time. In this the 65C02 was way ahead of the 6502. And the answer is simple - Being a CMOS processor, the 65C02 has a thinner silicon matrix and less resistance with that matrix. This gives is a faster processing speed on the nano-second level. Given time, nano-seconds adds up to microseconds and microseconds adds up to full seconds. But in today's world, who is going to worry about a couple nano-seconds? Back in the 1980s it was a necessity.
- - - - (Back to subject)
If the IIgs ROM 0 is gold because of people upgrading them, I need to test out my IIgs-Woz as it was given to me as a ROM 0. Whether it was updated over the years remain to be seem. I'm not even sure if it can turn on as the last time it was turned on was over 20 years ago. It might need a recapping of those two large caps that Uniserver mentioned needs recapping on the IIgs.
I'm not looking for a machine that runs GSOS though it would be nice to have.
But compared to a IIe, it depends on the IIe. If Joad has a not-upgraded IIe from 1982, it would be more valuable than the IIgs or IIc. This particular IIe would be better to own as a collector's item. If the ROM and CPU has been upgraded, then its value drops as a collector's piece. But like I believe you stated, what is the machine needed for - as a daily driver or as a museum piece?
A IIc is nice, but its not the perfect machine. Unless its a Rev 2 or 3 or it is a IIc+, it can not be upgraded. And those that can, only the memory can be upgraded. The Laser 128 (VTec's IIc Clone) has a slot on the side of the case to add a standard Apple II card to. On top of everything else the IIc has plus it has a Turbo Mode which the runs the CPU at 2Mhz (or 4MHz) which the IIc does not unless you put in a Rocket Chip or Zip Chip into the IIc! These accelerators alone are in the $500 range on ebay.