@deramp5113
Can a 720K 5.25 floppy drive + VSG adapter also be used on a Northstar SD controller, such as an MDC-A4?
Can a 720K 5.25 floppy drive + VSG adapter also be used on a Northstar SD controller, such as an MDC-A4?
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SOL-20 memory map
- Thread starter guibrush
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wperko
Experienced Member
- Joined
- Jul 4, 2007
- Messages
- 414
deramp5113
Veteran Member
Yes, it will work, but it will only use the first 35 tracks (out of 80) and only one side of the disk. The disks will interchange with other 96tpi drives connected to the Sol, but not the 48tpi drives that would have been used in the day.
Hugo Holden
Veteran Member
When I used Mike's great VSG, rather than powering it from batteries, I powered it from a 12V supply inside the disk drive housing:
www.worldphaco.com/uploads/EXTERNAL_DUAL_5.pdf
These excellent housings are available on mail order from Takachi in Japan, a standard product. They will even cut out the panel holes for you in their CNC department.
These particular housings are made from extruded aluminium and have a super tough scratch resistant coating. Very beautiful precision engineering, typical of the Japanese obsessed with perfection approach, I like it.
One other thing about Takachi, lets say you want some odd sized enclosure for a project. If you send them the dimensions, their CNC department will make them for you. I got them to make some non-standard enclosures for some IBM 5155 VDU's, they did a wonderful job on them and got the dimensions bang on:
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very well done, you‘re a master! I plan to do some external enclosure too, but I think that I will go for a more simple approach: I will use a SCCI CD-ROM enclosure, paint it in matching blue, and maybe ask a friend of mine to make 2 wood side panels.
But first, I have to make the whole thing play together.
But first, I have to make the whole thing play together.
Hugo Holden
Veteran Member
Can you really fit two drives in there along with a good sized PSU and the VSG into one of those housings ? (You might, if it has the properties of the TARDIS, bigger on the inside than the outside). You need twin drives, if it is to be of great use.
One thing I found about powering disk drives (Hard disk or Floppy) it pays to have an SMPS which is a much higher current capacity than the drive's running current, otherwise when the motors start and there is a transient current increase, the SMPS supplies can detect an overload error and shut down. Analog supplies are not as problematic in that respect. But SMPS are more efficient and require less cooling. Don't forget to provide adequate ventilation.
Even more important to have a good supply if two drives are present, running together.
Plus, if you go for a larger SMPS, the ripple currents in the electrolytic caps (which generate heat in them on account of their ESR) work out much lower and the supply is much longer lasting. This is why I used the RD-65 SMPS, which seems, on the face of it, to have a much higher power capacity than required, but the Devil is in the detail I can promise you that. As noted in the article, this includes mains(line) wiring & Earthing & Fusing considerations too, unless you go for some type of pre-manufactured external dual 12V/5V DC supply, but that solution is not very elegant.
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Hugo Holden
Veteran Member
I didn't say "mandatory" to have dual drives, you could just have the one, but you will soon find yourself wanting two drives once you start to play with the working CP/M system, one is more limiting than two. It is like most computers, when it comes to drives, the more the merrier.
wperko
Experienced Member
- Joined
- Jul 4, 2007
- Messages
- 414
Hi, The BOOT drive containing CP/M has to ReLoad after running programs that typically clobber lower memory where CP/M loads. So, having two drives means leaving the BOOT disk in drive A: and the programs 'n games floppy in drive B:
This is the awesomeness of Mike Douglas' FDC+ Serial Drive Server ... on my Altair 8800 I get four disk drives and it saves me a ton of shelf space.
.
This is the awesomeness of Mike Douglas' FDC+ Serial Drive Server ... on my Altair 8800 I get four disk drives and it saves me a ton of shelf space.
.
Hugo Holden
Veteran Member
The thing with the number of disk drives reminds me of "The Fish Bowl problem":
You go into a pet store and see some Goldfish in a small bowl and buy them. After a while you like them and cannot stand to see them in such a small enclosure. You go back to the pet shop and buy a small aquarium. That is better but after a while you can see it will accommodate a few more fish. Very soon, it is too crowded, so back to the shop to buy a bigger aquarium. Later though, it looks a little dark in there with the increased volume, so you buy some overhead lights for it, and incorporate an external pump & filter unit.
Then the process repeats on a larger scale, until you have a Fish tank that is as long as a wall in your living room, pipes running down through holes in the floor, to filter units in your basement and a Tank full of many Fish, enough to give a Great White Shark one decent meal.
The lesson is; don't shoot too low initially, somewhere in the middle usually works out well.
You go into a pet store and see some Goldfish in a small bowl and buy them. After a while you like them and cannot stand to see them in such a small enclosure. You go back to the pet shop and buy a small aquarium. That is better but after a while you can see it will accommodate a few more fish. Very soon, it is too crowded, so back to the shop to buy a bigger aquarium. Later though, it looks a little dark in there with the increased volume, so you buy some overhead lights for it, and incorporate an external pump & filter unit.
Then the process repeats on a larger scale, until you have a Fish tank that is as long as a wall in your living room, pipes running down through holes in the floor, to filter units in your basement and a Tank full of many Fish, enough to give a Great White Shark one decent meal.
The lesson is; don't shoot too low initially, somewhere in the middle usually works out well.
Still waiting the Northstar from my friend to arrive. If this card work, I will certainly go the dual floppy route, you are right.
Meanwhile, I'm not really sure that my problem come from the floppy controller of from the SOL-20, because I have some strange behaviour without the floppy board plugged too on the SOL-20. None of them prevent me to launch .ENT programs, I did many many testing and launched all games that I could more than 4 times, and it worked every time, what was not the case with the floppy controller board plugged in. But still, those problems exist:
-the cassette interface isn't working (but it's maybe because I'm not using the right cassette player. I tried with an iPod and with the jack output of a Surface PC).
- sometimes the command "SET I=1" return a "?" instead executing itself (but it's very rare). In fact, I saw that only when I use the music program combined with the sound board (very nice piece of hardware), when I exit the program and type "SET I=1", I have to make it twice sometimes, the first time give a "?" back.
- when I power on the SOL-20 I have to wait about 3 minutes to be able to make a transfert of a .ENT file, otherwise the transfert is garbled.
But on the other side, the ROM chip on the floppy controller runs hot, very hot. I tried to remove it and operate the board, but the problems remain, the SOL-20 is very buggy after some minutes, letting me think that it's maybe a heat problem. What is very strange is that even if I remove the floppy controller, the SOL-20 continue to corrupt .ENT softwares loaded via the serial port. I have to power it on for a moment, about 15 minutes do the trick, to have it back in a stable state. Very strange behaviour...
Did anyone experienced one of those symptoms already on his machine?
Meanwhile, I'm not really sure that my problem come from the floppy controller of from the SOL-20, because I have some strange behaviour without the floppy board plugged too on the SOL-20. None of them prevent me to launch .ENT programs, I did many many testing and launched all games that I could more than 4 times, and it worked every time, what was not the case with the floppy controller board plugged in. But still, those problems exist:
-the cassette interface isn't working (but it's maybe because I'm not using the right cassette player. I tried with an iPod and with the jack output of a Surface PC).
- sometimes the command "SET I=1" return a "?" instead executing itself (but it's very rare). In fact, I saw that only when I use the music program combined with the sound board (very nice piece of hardware), when I exit the program and type "SET I=1", I have to make it twice sometimes, the first time give a "?" back.
- when I power on the SOL-20 I have to wait about 3 minutes to be able to make a transfert of a .ENT file, otherwise the transfert is garbled.
But on the other side, the ROM chip on the floppy controller runs hot, very hot. I tried to remove it and operate the board, but the problems remain, the SOL-20 is very buggy after some minutes, letting me think that it's maybe a heat problem. What is very strange is that even if I remove the floppy controller, the SOL-20 continue to corrupt .ENT softwares loaded via the serial port. I have to power it on for a moment, about 15 minutes do the trick, to have it back in a stable state. Very strange behaviour...
Did anyone experienced one of those symptoms already on his machine?
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Hugo Holden
Veteran Member
There are so many things that could put a monkey wrench in the works. To say nothing of those original pale blue CTS switches.
But, apart from that, if this was my SOL-20, I would:
1) Get rid of the micro complex modification.
2) Fit an original personality module with SOLOS
3) Remove every IC on the mobo, and S-100 boards and check the IC sockets and clean the IC pins.
After that, to create a perfectly working SOL-20, perhaps go back to the micro complex if you really want it.
But, apart from that, if this was my SOL-20, I would:
1) Get rid of the micro complex modification.
2) Fit an original personality module with SOLOS
3) Remove every IC on the mobo, and S-100 boards and check the IC sockets and clean the IC pins.
After that, to create a perfectly working SOL-20, perhaps go back to the micro complex if you really want it.
in theory, I totally agree with you, but in practice, there is no manual on the web that explain the modification needed to put the micro complex board In the SOL-20, and therefore no idea what has to be reversed (trace cutting, IC changed....), and in addition, about 36 IC where removed to put this board in place, and I of course don't have them.
In other words, I'm pretty sure that trying to remove this thing is not trivial. But you're right, it can good be that the Micro Complex board is the culprit. I hate this board
But removing all the ICs and cleaning then is a good thing to do, yes. Testing the soon to arrive loaned Northstar controller will tell me more about where the problem sits I think. If the machine continue to behave incorrectly with the Northstar, then there is definitively something wrong in the SOL-20 itself. Lee Felsenstein told me in the S100 Facebook group to check the 5V for constituency, ripple and noise, it's a good start too.
I will report when I have more news.
Thanks
In other words, I'm pretty sure that trying to remove this thing is not trivial. But you're right, it can good be that the Micro Complex board is the culprit. I hate this board
But removing all the ICs and cleaning then is a good thing to do, yes. Testing the soon to arrive loaned Northstar controller will tell me more about where the problem sits I think. If the machine continue to behave incorrectly with the Northstar, then there is definitively something wrong in the SOL-20 itself. Lee Felsenstein told me in the S100 Facebook group to check the 5V for constituency, ripple and noise, it's a good start too.
I will report when I have more news.
Thanks
Hugo Holden
Veteran Member
in theory, I totally agree with you, but in practice, there is no manual on the web that explain the modification needed to put the micro complex board In the SOL-20, and therefore no idea what has to be reversed (trace cutting, IC changed....), and in addition, about 36 IC where removed to put this board in place, and I of course don't have them.
In other words, I'm pretty sure that trying to remove this thing is not trivial. But you're right, it can good be that the Micro Complex board is the culprit. I hate this board
But removing all the ICs and cleaning then is a good thing to do, yes. Testing the soon to arrive loaned Northstar controller will tell me more about where the problem sits I think. If the machine continue to behave incorrectly with the Northstar, then there is definitively something wrong in the SOL-20 itself. Lee Felsenstein told me in the S100 Facebook group to check the 5V for constituency, ripple and noise, it's a good start too.
I will report when I have more news.
Thanks
It is going to take more than checking the +5V supply for ripple & noise.
But, you don't need a manual or step by step instructions to tell you how to reverse the micro-complex modification.
You have the SOL-20 hardware manual (readily available online) and you just make sure that your computer conforms to that configuration.
To do it, simply fit all the original IC's (easy to get) and then study the specific areas where the micro complex mod was patched in. Make sure that the schematic "you end up with" simply matches the SOL manual. It is not rocket science.
Though having said that, one of the most clever equations I have ever seen in rocketry, corrected an object's trajectory for loss of mass with time, as it is accelerated by a fuel burn, because of the simple fact that the fuel is being used up and as a result the mass of the rocket is dropping. It was of Russian origin, from their early space program in the mid 1950's.
Of course, when you "undo" the microcomplex modifications, if you can take a detailed record of that, then you will be able to create a manual of how to re-fit the microcomplex system to a SOL-20. This will then provide others with help and support to fit this system (or a replica of it) where the information is currently not easy to find. Always take the opportunity to help others with their vintage computers, it is the basis of this Forum.
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