Posted By
MMS
on 2016-09-19
16:36:39
 |  Re: What would I do differently in the Plus/4
wooow, gerliczer, it is a really fantastic list! And fully with you.
Lot of very true statements. (only RAMEN I do not know what it is)
Only one point I may add: based on my recent digging in technical documents and some C64 user port related circuit diagrams/projects I noticed, that despite different namings in the C64 and Plus/4 documents, the two user ports (or at least te most critical serial communication lines) are more similar to each other than we ever though.
I suppose (not tried out yet, especially as there is no real useful PRG) that the C64 / VIC-20 Modems will properly work on Plus/4 too. So I should buy a modem first 
JamesD: actually there are TWO implementations for IEEE-488 for smaller 8 bits.
1) what made by Commodore for VIC-20 officially, and later cloned to C64: a full, proper IEEE-488 interface on the Expansion port. Fast and reliable, behave as a PET. Called VIC-1112 cartridge.
It is not SO complicated (ehehehe) but would add several new components to the Plus/4 circuitry.
So a built in Kernal support, and at least one really intergrated IC (or 4-5 more) would be required, and it is really against the original "cheap, low IC #"concept:
http://www.zimmers.net/anonftp/pub/cbm/schematics/cartridges/vic20/ieee-488/index.html
2) Some cheaper implementations (like mine, but was not cheap at all) is based on Jochen Adler design is putting an IEC to IEEE-488 interface on IEC port.
It fully translates the IEC commands to IEEE-488 port, but slow as hell. Or the same as normal IEC with 1541, I mean normal snail speed
It supports JiffyDOS (so theoretically could be blazing fast on a parallel port) BUT I think there is no JiffyDOS EPROM for any IEEE-488 type floppy I am aware.
Details:
http://www.nlq.de
The list of component, cost:
http://www.zahnarzt-adler.de/nlq/ajni2blt.txt
Soooo, it will be always 400byte/sec speed, till someone develops a JiffyDOS ROM for an IEEE-488 devices (if it may work at all via a parallel cable).
But at least it works on Plussy too. Unfortunately not perfect, as my SFD1001 reacts tothe commands, but does not format and read anything. probably need a head cleaning....
I hardly believe someone will design and produce a 1) type full feature IEEE-488 cartridge for Plus/4
And finally a nice (and I think best ever) summary about the fantastic Commodre drives, starting with the SFD-1001 (Super Floppy Disc) :-D
http://www.floodgap.com/retrobits/ckb/secret/periph.html
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