• Please review our updated Terms and Rules here

C64-Link II -- what is it?

falter

falter

Veteran Member
Joined
Jan 22, 2011
Messages
6,576
Location
Vancouver, BC
Hi there,

Among the many boxes of C64 stuff I have, I have this little adapter called C64-Link II RTC. I dimly remember these being used in a computer lab at our school -- but not sure how. Were these just a way of allowing multiple C64s to access a common disk drive? As I remember in the lab, there was a 2040 (?) that served as the drive for all 20 of the C64s in there. I think too when you fired them up what came up on screen was a bit different. Not sure... anyone recall? :)
 
Google redirected me to this old review from the Hires (?!) magazine, May-June 1984:

http://www.atarimagazines.com/hi-res/v1n4/reviews.php

You seem to be correct about it works as an IEEE interface and Basic extention. I don't know about the ability to connect multiple C64's to it, perhaps through additional hardware like the VIC switch, MBS-nnn that may have been discussed on this forum before. The review mentions the firmware on the original version was located to $8000 and was a problem to many programs that would use RAM beneath. Perhaps the V2 that you got solved that problem so it is more transparent to the computer. You should be able to tell if you insert it into a C64 and power on. If you are greeted with 30719 bytes free instead of the usual 38911 bytes free, it is an indication the cartridge has hogged the $8000 block.
 
carlsson said:
Google redirected me to this old review from the Hires (?!) magazine, May-June 1984:

http://www.atarimagazines.com/hi-res/v1n4/reviews.php

You seem to be correct about it works as an IEEE interface and Basic extention. I don't know about the ability to connect multiple C64's to it, perhaps through additional hardware like the VIC switch, MBS-nnn that may have been discussed on this forum before. The review mentions the firmware on the original version was located to $8000 and was a problem to many programs that would use RAM beneath. Perhaps the V2 that you got solved that problem so it is more transparent to the computer. You should be able to tell if you insert it into a C64 and power on. If you are greeted with 30719 bytes free instead of the usual 38911 bytes free, it is an indication the cartridge has hogged the $8000 block.
Click to expand...

Yes... I think I remember more clearly now. There were 20 computers in the lab, and they were all 'chained' to that 2040 drive I mentioned (I think it was a 2040). There was also one 'master' computer for the teacher that had a colour screen and its own drives. I think that one was completely separate. When you tried to run certain programs on the 'networked' 64s, very often it wouldn't work -- I'm guessing that's due to the $8000 block being taken up. I might be mistaken, but I seem to recall the teacher being able to run something that caused all 64s to load certain software at once?

Interesting. Yes, if I recall correctly, there was a ribbon cable or something that attached to one of the interfaces on the C64 Link and went to another C64 Link on another computer and so forth. I think, anyway -- it's been 20+ years.
 
Yes, very likely. In the last few years, I have come across some PET networking hardware which worked in the same way you describe: each PET computer had its own daughter unit which connected with a ribbon cable to the next PET unit. At the end of the chain, the last PET would have a master unit which was connected to e.g. a floppy drive.
 
I have both the RTC Link and Link II. Yes, they are IEEE cartridges for the C64. I might have the manual for the Link II here somewhere.
When I was in high school we had a lab of 6 PET 4032's and one 4040 drive. All 6 PETs were attached to the one drive and all could access the drive as long as it was only one at a time.

Steve
 
sjgray said:
I have both the RTC Link and Link II. Yes, they are IEEE cartridges for the C64. I might have the manual for the Link II here somewhere.
When I was in high school we had a lab of 6 PET 4032's and one 4040 drive. All 6 PETs were attached to the one drive and all could access the drive as long as it was only one at a time.

Steve
Click to expand...

If you ever find that manual please do let me know... apparently this device requires a direct connection to certain pins on certain chips inside the C64? I don't have any wires or anything with this LINK II .. just the unit itself.
 
I don't have the Link II handy but I'm almost 100% positive that it should work without any extra connections. I will try to find the manual for you to confirm.

Steve
 
The Link II definitely does require wiring two signals into the C64. The manual can be found at http://mikenaberezny.com/hardware/peripherals/rtc-c64-link-ii/.

I used a Link or Link II, I'm not sure which, many years ago. I'd really like to get my hands on one to dump the firmware and reverse-engineer a schematic. I suspect that a modern redesign could be done that wouldn't require the two wires into the C64. I haven't verified this, but I think one of the signals is an address decode, and the other is an output pin on the 6510 I/O port, and both could be replicated by logic inside the cartridge. Back in the early 1980s that would have made the cartridge bigger and more expensive.
 
Just a followup... The Batteries Included Buscard II IEEE cartridge also has one clip that goes inside the machine, similar to the RTC link II. According to the buscard manual the connection makes it more "transparent". I assume this means if you map out the c64 roms, the buscard rom will also map out.

Steve
 
I'm looking for a ROM image to burn for my dead C64 Link IEEE-488 cartridge. A Link II image may also work. Any help would be appreciated.
 
mdrobot said:
I'm looking for a ROM image to burn for my dead C64 Link IEEE-488 cartridge. A Link II image may also work. Any help would be appreciated.
Click to expand...

I will try to dig out the Link and read the ROM for you. I have the ROM for the LinkII but I have no idea if it will work in the original Link.

Steve
 
I found my RTC Link I and opened it up... Bad news: The ROM (eprom) is soldered in. Plus the board is very weird. It actually consists of three boards sandwiched together - the inside board has the cartridge pins and IEEE connector, and on both sides of this board are the boards with the components. It's one of the wierdest cartridges I've seen, no doubt built this way to fit inside a cable shell.

For the RTC Link II board they managed to fit everything on a single board AND socket the EPROM...

Anyway, I'm not too eager to try desoldering the eprom chip in order to read it. What I can try to do is plug it into the C64 and save the rom from there. I might create a web page for these units. I'll update you if I have any progress.

Steve
 
sjgray said:
I will try to dig out the Link and read the ROM for you. I have the ROM for the LinkII but I have no idea if it will work in the original Link.

Steve
Click to expand...

No it didn't, probably that bankswitching thing it does. Whenever you have time to read the first one on your 64, would be great. By the way, I was reading your website, and wondered if you had got OS-9 working on SuperPET? I used OS-9 on the TRS-80 Color Computer 3 (Coco3). It's sweet. (OS-9 that is)
 
mdrobot said:
No it didn't, probably that bankswitching thing it does. Whenever you have time to read the first one on your 64, would be great. By the way, I was reading your website, and wondered if you had got OS-9 working on SuperPET? I used OS-9 on the TRS-80 Color Computer 3 (Coco3). It's sweet. (OS-9 that is)
Click to expand...

I tried plugging in the Link I and it doesn't seem to work on my 64C. I vaguely remember trying it a while back and having the same problem on my 64C, but working on an original C64, so I will have to try it again.

I'm still working on getting OS-9 working on the SuperPET. I have two boards that I need to populate. Yes, I also have a Coco3 and I have run OS-9 on it.

Steve
 
Update: I got the Link I working on a regular 64. I cleaned the gold contacts on the board and that seemed to fix it. I saved the rom to disk and just need to transfer it to the PC to post. Unfortunately I'm having some problems with my zoom floppy driver so I have to sort that out first... hang in there...

Steve
 
Finally...

I still haven't sorted out my Zoom Floppy problems, but I did manage to transfer the ROM image using the uIEC...
I used the mdump program. It created a 16K file plus two bytes for load address. Transferred this via uIEC. On the pc I used a hex editor. I removed the load address and trimmed it to create a 4K rom image.

With the RTC Link II rom I dumped that directly from my burner, so I am confident about the contents. With the Link I ROM, because of these extra steps I have to add the disclaimer that the image is not verified. Anyway, let me know if it works....

Steve
 
sjgray said:
Finally...

I still haven't sorted out my Zoom Floppy problems, but I did manage to transfer the ROM image using the uIEC...
I used the mdump program. It created a 16K file plus two bytes for load address. Transferred this via uIEC. On the pc I used a hex editor. I removed the load address and trimmed it to create a 4K rom image.

With the RTC Link II rom I dumped that directly from my burner, so I am confident about the contents. With the Link I ROM, because of these extra steps I have to add the disclaimer that the image is not verified. Anyway, let me know if it works....

Steve
Click to expand...

It definitely works! Thank-you very much. This gets me back to where I was before my ex pitched my BusCard II in the trash.
 
You must log in or register to reply here.
Back
Top