Posted By
JamesD
on 2016-09-17
01:37:32
|  Re: What would I do differently in the Plus/4
Ok, why does the C64 matter here? I'm not trying to turn the Plus/4 into C64 part 2.
I'm trying to give it features that make it look more professional, give it more things the C64 doesn't have, and keep the custom chips pretty much the same. I'm basically trying to improve on the idea of selling it as a business machine, which is what Commodore already did.
Commodore didn't leave the educational market. They just never had that much of it after 1980. At least not in the US. Frankly, they didn't have any of the US market where I was from even before that.
They actually had an education program trying to promote the Amiga in schools. It was one guy and an assistant. I met them a couple times. By then schools were pretty focused on PCs and Apple by then other than video editing. I saw a couple demonstrations, and everyone was impressed... but never willing to buy.
I demonstrated the Amiga to several schools and school districts myself and it was like talking to a brick wall.
The head of a local educational service unit was stuck on the idea of using a PC to control a video disk for education. We are talking over $5000 in equipment, plus pressing content onto custom video disks.
A CDTV could have done it for under $1500 with just a CD burner and an authoring system to digitize and convert the video. But they didn't want to hear it. I was doing as much off of floppies as they were!
The 65802 and 65816 weren't available until a few months before the Plus/4 came out so the Plus/4 design would have been pretty much committed to a 6510 derivative by then.
MOS didn't own them either, so Commodore would have had to make the machine more expensive.
Now that you mention it, MOS didn't even own the 65C02 so that would be out as well and it's a non-starter anyway. Oh, and I believe WOZ said the first 65816s were buggy... so not shipping a Plus/4 with it in 1984.
FWIW, the Apple IIe came with the 65c02 and it didn't give Apple any problems.
I've also written 65c02 code. In my case, the code was about 5% smaller than without the 65c02.
And the old JMP instructions are the same, it just adds a new variation for calling via tables.
My code used it, a self modifying 6502 version, and a rommable 6502 version selectable with a define.
In RAM, it's a bit of a wash using the new JMP mode, but in ROM it saves quite a few clock cycles and instructions.
The 65816 would certainly have been worth putting in the machine in my view, especially if you want to support more RAM from BASIC. Then you can have megabytes at your disposal instead of kilobytes and better support for high level languages. The heck with UCSD Pascal, include a native code compiler!
Sadly, I don't think you could have pitched that to management. It started as a $60 machine and they were trying to re-purpose the hardware for other sections of the market. They were already open to the business machine idea, so I just expanded on that in a way I thought would be more successful. I think Commodore was also planning on a Z8000 workstation at that time, since they had that running in 1985 which might have made it an even tougher sell to management... not that the Plus/4 could have competed with that machine.
The only way I see something like that happening, is if work had progressed on the 6516 (sometimes referred to as the 6509, a chip that was proposed back in 1978(?). See MICRO the 6502 Journal for a brief discussion of it), Commodore might have been able to purchase the rights to that. That would have pretty much been what the 65802 was but much earlier.
Commodore could have directed MOS to work on the idea themselves based on what was published, but that would have required a CEO with a little more vision. That could have even made it into the C64 given the timeline. But that is way out in what if land, I'm proposing simple changes I know they could have done.
The 1571 isn't difficult to use. That's all I used on my Plus/4 since I also have a 128. It even works with the C64 and VIC20 as a single sided drive. It only starts in double sided mode or uses high speed when the C128 talks to it and the C128 can fall back to single sided mode for making C64 disks. Just add those features to the Plus/4 OS.
The reason I suggested using the 1571, is that it doubles the storage per drive to makes it more competitive against the machines I mentioned.
It's pretty fast, not quite Jiffydos fast but not off by a lot if you see the benchmarks.
It also takes two of the competitors drives to store a similar amount of data.
I think the 1571 would actually store about 50K more than a dual drive TRS-80, and 70K more than a dual disk Apple!
The 1571 was supposedly $300. That's competitive to what a controller and two drives cost on another systems rather than appearing expensive like when the 1541 was introduced. And you can add greater disk capacity than other systems just by adding a 2nd drive or more.
If you think about the possible advertisements and compare features vs Apple, Atari, TRS-80 Model III...
it looks pretty good.
When the inevitable comparison to the C64 is made, sure it doesn't have sprites or a SID, but look what it has the C64 doesn't. It doesn't look like a cheap machine, it looks like a more professional machine.
At least that was my goal here. It might have flopped anyway, I just think it would have done better.
The cult of Apple was strong even then.
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