Silent Q

Posted By azog on April 17, 2012

This is a project I’ve been working on for some time. But it doesn’t work. I normally don’t like to post a half-assed project like this, but perhaps the rant will help me think of something, or perhaps someone will stumble on this and have an idea…

This is the GIDE (generic IDE) kit for the P112. This is built and installed. Hard to tell, but the P112 is below the GIDE, and connects via a three row series of headers near the left. I had to remove the battery from the P112, since it stood too tall to allow the GIDE to install. This is/was a known issue, and you can see that I’ve simply placed the battery on some double-sided tape and ran three conductors of some ribbon cable back to the P112.

The Compact Flash interface is not part of the GIDE kit. I purchased that separately for like $5 on ebay, shipped from Hong Kong. They’re really cheap. There’s no logic on the interface at all. I think CF is actually a subset of IDE.

The 128mb is a card I had laying around, and seemed like a reasonable size for an 8-bit system. For those who’ve never used a CP/M system, and are used to terabytes of disk space, 128mb is huge.

The CF interface is plugged directly onto the GIDE and uses a 3.5″ power connector. IF I ever get it working, I’ll need to preposition it so that it fits inside the enclosure. I wonder if there are 90 degree gender benders for headers? But that’s for a later date…

The GIDE arrives in a kit that is significantly easier to build than the P112. That’s because all the logic is inside two GALs, so the developer of the GIDE must have spent a good portion of time developing the GALs.

There are a couple of options you can select during building, the most important being how the GIDE will install onto the P112. If the GIDE is going on top, like mine, the headers get soldered from the component side. If the P112 is on top, the headers get soldered from the solder side.

I chose to add one other option mentioned in the build guide, a DIP switch for the address selection.

You can see the DIP switch at the upper right, and it is set for 50H, which is the default. I could have hard-wired it with jumpers, or even put a socket, but I opted for a DIP switch because, even tho it’s unlikely I will ever change the address, it gives it a really good visual finish. Yea, that’s a bit of vanity.

Problems…

The GIDE comes with a boot disk, but it does not boot. If you look at a previous post, I mention I am having issues booting some of the disk images. The provided boot disk behaves in the same way, reporting “OS loaded, booting…” and then ceases.

CP/M 3.0 boots, but when I run fdisk, it reports it cannot read the IDE partition, which I am assuming means it cannot FIND the IDE device.

It these intermittent issues that are causing me frustration. If CP/M 3.0 boots, why doesn’t CP/M 2.2 or Z? Each time I create a disk from an image, I format it, and re-write the image, and then write-protect the disk to make sure nothing gets accidentally erased.

If I accidentally blew the disk controller chip (the other SMT device besides the Z180), I would imagine it wouldn’t boot AT ALL. If I accidentally blew the GALs, then the same behavior above should be apparent.

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Posted By azog on April 10, 2012

Well, this is a bit of sad news. Jack Tramiel passed away on Sunday April 8 2012:

http://www.forbes.com/sites/davidthier/2012/04/09/computer-legend-and-gaming-pioneer-jack-tramiel-dies-at-age-83/

Thanks, Jack.

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Posted By azog on March 7, 2012

I’ve been browsing eBay for an enclosure for the P112 kit I recently built. It’s kind of hard searching for “external drive enclosure” because you end up with thousands of USB floppy drives. I could have installed it in a PC case, but that’s not very classy. I wanted it to look “different”.

I just decided to Google around until it gave me more ideas than eBay alone, and I found a good candidate in the form of an HP 9122 external HPIB drive.

I found a few of these listed on eBay with insane starting bids of like $200, even when blatantly non-working. I was quickly outbid on the ones that were “reasonable” in terms of price, until I found this 3rd party version of the 9122. It was posted with the infamous “tested, powers on” status, but I was more interested in the enclosure, power supply and possibly the drives. I didn’t care if the IEE488 interface worked or not.

It’s better, because if you look at an official HP 9122, they use funky floppy drives. This one looked like it uses PC style drives.

The rear view is pretty bland. An HP-IB interface and address switches, selectable voltage input and a fan.

Opening it up to assess the possibilities was encouraging.

It’s very well designed. Nice, clean layout. Everything looks modular. So I removed the floppy mounting bay to expose the controller board underneath.

Some interesting chips on there: a Z80, RAM and ROM, and a bunch of other stuff. I’ll set this controller aside. The controller is mounted on standoffs. Yet another bonus.

The floppy mounting bay is equally nicely designed. This is the view from the bottom.

They appear to be standard PC style 3.5″, 1.44mb floppy drives. Because of the mounting, I’m not too concerned about the drive functionality, as they can easily be replaced. But it would be bonus if they worked.

So now that I’ve got the controller and floppy bay removed, I can give it a once-over to see how to mount the P112 itself. The power supply stays, as it has a standard 4-pin Molex connector and two 3.5″ floppy power connectors.

The first test-fit shows only one of the mounting standoffs is in a suitable location. You can’t see it in this picture, it’s hidden behind the battery. I’ll have to move the other three.

Since I’m inept, this was the hardest part of the whole project. How to drill holes in the proper location? I found a 3.5″ floppy sled that had the right holes, so I used that as a template for drilling.

I wanted a reset switch, so I poked a hole right thru the front panel.

Build up a simple wiring harness, mount the P112, and test it. I also wanted to re-use the original power LED, but that was connected to the original controller, so I just soldered some random 120 ohm resistor to it, and connected it straight to the 5vdc supply.

I don’t know what to do with the P112 console cable, so I simply routed it loosely thru the now-empty IEE488 port. Again, ineptitude will prevent me from trying to cut a hole in the back panel to mount the console cable, and the P112 itself blocks me from kludge-fitting it to one of the empty screw holes.

So now it’s just down to the floppies and testing the whole thing. Since everything up to now went pretty smoothly, I figured it was a good time for something to go wrong.

Using the original two drive floppy system, I just connected them to the floppy header, but these original floppy drives don’t seem to work, or don’t work with the P112. I had a whole stack of other random floppy drives which I also tried. After about a week of trying every possible combination (single and/or double drive; single ended or double ended cable, with and without a twist, changing jumpers, etc), I got two drives to work, but neither has a bezel, which is unattractive but it tells me that things are generally operational.

I couldn’t really find any floppy drives for less than $20 on ebay, so I posted on a forum I frequently lurk. Someone mentioned an online retailer had 3.5″ floppy drives for $9. Sounded like a deal, so I ordered two for $22. I got them working, but I’m unhappy with them. Sometimes they seem to stop functioning. Maybe it’s related to this, below…

The P112 CD includes a variety of disk images. First I tried Z, but when it boots, the console says “OS loaded, booting…” and stops. I tried CP/M 2.2 with the same results. I ended up using the CP/M 3.0 image, which worked with an odd caveat.

At some point in the boot process, the console switched from 9600 to 19200 baud. You can see the baud rate on the status bar. I’ll figure that one out later…

Here it is all bolted back together. Can’t tell much of a difference from the original box, can you? Oh, and I make no apologies for the Hello Kitty. People who know me know I’m an unabashed fan of Kitty, and I decided to make her kind of a “signature” for completed, or semi-completed projects. You’ll be able to deal with it :)

I named this “part one”, as I still have to address a few issues:

#1 – What’s the deal with the original HP floppy drives?

#2 – Mount the console port. Actually I’d like to mount the “other” serial port, and perhaps the printer port too.

#3 – I’d like to eventually get a GIDE kit, at which point I’ll need to lose one of the floppies and all the above grief will be for naught.

#4 – figure out why Z and CP/M 2.2 won’t boot. UZI did, and so does CP/M 3.0. What’s the difference? I can READ the 2.2 disk while CP/M 3.0 is running, so it’s not a corrupt image.

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Posted By azog on February 23, 2012

Repeat after me: penultimate simply means the next to the last. It is not an intensifier equivalent to “awesome”. It is a fun word, but so is blunderbuss, and one wouldn’t say “that was one blunderbuss of a game”. I know words change, but this kind of change has to stop. I guess I’m being obese over it because it is irksome.

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Posted By azog on February 22, 2012

Wow, I’m super excited. I ordered a “ST Multimode video cable” from Best Electronics. This is a cable for an Atari ST (which I’ll probably post about at a future date), but will allow you to run all the video modes of an ST on one cable. The idea is that you connect this into one of the converter boxes I recently posted about.

Now, before I go off, I want to mention that they didn’t pay me to endorse them, so consider this a neutral opinion, but I would have no problem recommending Best for any of your Atari needs. Besides the fast shipping and prompt, courteous service, they’re one of the dwindling few businesses that still deals with Atari, and I feel it’s important to support businesses such as these, otherwise they’ll disappear.

But anyways, as to the cable, it has an Atari ST 13-pin DIN connector on the Atari ST, and a VGA connector on the other side. There’s also an RCA jack for audio.

There is a switch which selects between the color and monochrome modes. If you’re not familiar with the way an ST deals with “high” resolution, it senses a low-level signal on the “monochrome detect” (and does a reset if necessary). According to the DIY cable guides, once you do this, you just tie RGB together and feed them to “monochrome input”. I figure is exactly what this cable is doing.

Now knowing the color modes are basically CGA but monochrome is basically VGA, I plugged this in, and figured if I didn’t get a signal, I would try the other switch position (it’s not labeled) to test for monochrome. To my utter surprise, when I turned on the ST, it was in ST Medium mode. Whoa.

So of course, I switched to ST Low mode, figuring if Medium worked, that Low would also.

Well, now comes the monochrome test. Just press the switch, the ST resets, and what do I see (poor picture quality, but it looks better IRL).

It appears with this TV, I don’t NEED a converter box! I’ll have to play around with it, and see what the color quality is. If I can find an ST palette tool, that would be helpful. But for now, I’m kind of stunned.

The TV is a Coby TG-TV1514:

It’s an older Coby model, probably discontinued, but I picked it up from ebay for what seemed like a reasonable price. It had S-Video (which I want), and lacked HDMI (which I didn’t want), so it was almost ideal.

I might try it on my Commodore 128 in RGB mode.

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Posted By azog on February 21, 2012

Have you ever experienced “peanut rage”? That feeling that you get when you open a package, only to discover it’s been shipped in styrofoam peanuts?

I don’t care if they’re cost effective. I don’t care if they’re biodegradable. I don’t care how well wrapped the item inside is, there always seems to be peanut particles that find their way thru any possible ingress point.

They’re disgusting. I wish they were never invented.

Am I the only one to feel this way? And are shippers who use these things unaware of the wonderful reception waiting at the receiving end?

I won’t leave negative feedback based on shipping in peanuts, because negative feedback is forever. And I don’t contact the shipper, as the reception I’ve received, even when politely worded, is usually returned in vile.

Oh sure, they’re “recyclable”, in that if I ever need to ship something out, I can reuse them. Why would I, knowing how much I detest things things? So I won’t subject the other person to the same thing. At least bubble wrap is recyclable in this manner.

So they sit in a box or something, and maybe I periodically put them in the trash, further contributing to the problem.

So I rant. Yea, there’s more important things to rant about, but here it is.

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Posted By azog on February 16, 2012

Lately it seems a large chunk of my retro computing hobby is devoted to display issues, notably trying to get a modern display to work with older computers. “Modern display” would be generally an LCD VGA panel, for the simple reason of size as well as possibly interchangeability between disparate video systems.

I guess the purpose of this post is both a vent, and perhaps if someone, somewhere in the world stumbles on it, and tells me about a magic universal solution.

Since my attention is on Commodore 8 bits and Atari 16 bits, I’ll use these as the examples, but the same issues can easily be transported to other systems.

The VIC-20 normally outputs composite video, but mods exist for S-Video. The Commodore 64 can natively output both composite video and S-Video. The Commodore 128 is slightly different, as the 40 column mode is the same as the C64 (composite and S-Video), but there needs to be special attention on the 80 column mode, which is RGBI.

For Atari 16 bits, e.g., the Atari ST, there are also three different resolutions, which run in two different video modes. ST Low and ST Medium are CGA, while ST high is close enough to VGA that it just works as VGA.

In the case of a C128, if you wanted both 40 and 80 column modes, you’d run either two monitors, or a monitor with both composite and RGB input. Same with an Atari ST, but in this case, you’d have no choice but to actually have two monitors, an SC1224 for color and an SM124 for monochrome, and a switch between them. Given the bulky sizes of CRT monitors, is it any wonder I want to have a hopefully single solution?

Composite, S-Video and VGA are not an issue. For example, here is the back panel of a not-quite-modern LCD TV.

This has a host of inputs: RF as pretty much the bottom of the barrel, composite, S-Video, component video, and what TV manufacturers often refer to as RGB, but is actually VGA. You need to be careful of their terminology there. All these video modes are analog video, and that’s a key issue.

The problem lies with the CGA or RGBI video modes. Actually, for all intents and purposes, the RGBI mode of a C128 is CGA, refering to either CGA or RGB(I) means the same thing. CGA is a digital signal, or TTL, and this is the same key issue as above.

I think the analog video modes all have a 1vpp signal, and TTL is, well, TTL, which is defined as 5v. Simply incompatible.

Voltages aside, another major difference between CGA and VGA is the horizontal sync rate (h-sync), which is roughly 15khz for CGA, versus roughly 31khz for VGA. So VGA is pretty much double the h-sync of CGA. Here, you will often find reference to “scan doublers”, but that phraseology seems to be mostly isolated to the Amiga community.

So there are two major incompatibilities which prevent CGA video being displayed on a VGA monitor. In the CRT era, many monitors were “multi-scan”, which would enable a sync rate down to 15khz, and up to like 60khz. But LCD monitors don’t seem to sync that low.

Why don’t they sync down to 15khz? I do know for a fact that there is a brand of LCD monitors that supports BOTH VGA AND CGA inputs, but they are barebone panels which usually cost in the range of $400. They’re targetted towards arcades who want to convert or replace CRT monitors with LCD panels.

Now, I’ve seen people post success or failures of attempting to connect TVs with VGA inputs to their CGA outputs, and I wonder how they’re doing this? Are they just connecting it and hoping there’s no Magic Smoke?

I mentioned scan doublers above, and there are a few different options. I used an ACV-011 in a previous experiment with my C128:

Another experiment was with the GBS-8220

They’re pretty much “more of the same”. The ACV has features the GBS doesn’t and vice versa. The labels on the GBS-8220 are clearer so I’ll use that as my focus.

The input from CGA is the header with wires heading off the top of the board, the other inputs and outputs are either not an issue at hand, or self-explanatory. You can see the signals on the board: VS (vert sync), HS (horizontal sync), S (composite sync, which combines both h-sync and v-sync), and the three colors.

So why can’t modern VGA panels support the CGA sync rates? The only reason I can think of is cost. “Nobody wants CGA”. While that’s not true, as the vintage or retro community is rather large, but probably not large enough to offset costs.

As far as I am aware, an LCD panel itself is digital. Not the video inputs, but the actual LCD panel. You have three pixels for each color, and the pixel is either on or off. That’s a digital signal. It’s up to the input drivers to take their respective signals and convert them to the “raw” signal an LCD requires.

Driving a “raw” LCD is not trivial. Here, for example, is the datasheet from an LCD SparkFun sells. Such a feat is beyond me. When I sit down with these datasheets and try to envision the process flow, I am quickly overwhelmed. Most of the comments mention using an FPGA to drive it, but that seems to be with the FPGA generating the signals, and not taking an external signal to drive it. Then you have to deal with the different sync rates, the different voltages, and who knows what else…

So to end this, WHY isn’t there a “universal” LCD that can support CGA as well as VGA, composite and S-Video? One that doesn’t cost an arm-and-a-leg.

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Posted By azog on February 14, 2012

The P112 is a venerable Z80 based kit that’s been around for a long time. Is that a redundant statement? It is similar to the older SB180 from Steve Ciarcia, which is no longer available. It’s also somewhat similar to the N8VEM, which is contemporary.

The N8VEM has a different target audience and methodology. I won’t go into full details of the differences, you can find them at their respective repositories, but the major difference is that the N8VEM is not a kit; you need to order every specific part, burn your own ROMs and so on.

I was lucky enough to catch a comp.os.cpm announcement that a few P112 kits were being offered, so I decided what the heck. This is the semi-finished project. Semi-finished, in that I need to find a chassis for it, and etc.

The P112 arrives in a bag o parts:

There are a few SMDs, such as the Z180 CPU, so the kit curator “pre-loads” all the SMDs. You’re left with the rest.

A bucket of components:

And IC sockets and the associated ICs:

So I start off by viewing and printing the construction steps. I think my soldering iron needs a new tip, because lately I’ve been needing to use flux paste on a regular basis. It’s better to be messy from the start, and get it right, then have to go back and do it all over again…

After everything, except the battery holder, is soldered in place, but before installing the ICs, I gave it a nice wash. First a scrub with isopropyl alcohol, then rinsing it off with plain water. You can do that, you just need to be careful. Make sure you get it dry immediately afterwards. Spray compressed air inside all the sockets and stick it under a 100 watt bulb positioned very close. I put a small fan near it as well.

Then once is all clean and dry, a visual inspection for solder bridges or leads in need of trimming. Insert the ICs and give it a shakedown boot, which didn’t work the first time. The kit curator was extremely courteous in his e-mail exchanges, but as always, it boils down to “user error”, so there’s no need to embarrass myself with further details.

First successful boot, pausing at the BIOS. You can see a disk error simply because there is no disk attached to it.

It uses a standard PC 3.5″ floppy, of which I have a few laying about. I created a boot disk from the image file on the CD provided (and not pictured here). There is an IDE interface available called the GIDE, and a posting dating a couple months back was fishing for interest in a production run, but so far, no word.

Now to find an enclosure.

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Posted By azog on January 24, 2012

I just finished reading Commodore: a Company on the Edge, and wanted to post about it.

The book is the history of Commodore from their early days until the departure of Jack Tramiel in 1984, at the same time they announced the Plus/4. A sequel is promised which will follow Commodore from Tramiel’s departure until the ultimate closure of Commodore in 1994.

This book doesn’t cover things like the C128, the near-mythological C65, Q-Link, and etc. Those are all from the post-Tramiel era. My own personal interest in Commodore ends with the death of their 8-bits, having no interest in the Amiga, then or now. But Tramiel was also involved with the early phases of the Amiga, so I hope the second book will follow him, at least incidentally, on his next venture.

(edited on Feb 21 – please see the comments section for an excellent discussion on why the last part of the above is wrong)

When I migrated off my C128D, I had full intentions of moving to the Amiga, but for some reason, I never quite got there. I think in some ways it was the mentality of the Amiga crowd that turned me off, in the same way that I find Apple fans distasteful. When the time came for me to move to a 16-bit computer, happenstance would have me opting for an Atari ST, and I followed Atari thru the Falcon and the Jag, until their own death. It took me about 10 years to learn that I was unknowingly still following Tramiel’s ventures.

I think it is important to remember these histories and I would recommend this book to anyone who is interested in this era of history. The Apple-centric mentality of today would try to erase the history of Commodore. The book details various incidents of this type of revisionist history, where it is more important to feed a companies PR image rather than document reality. A short while ago, I was in Target looking for TVs with an S-Video input, and the college-aged salesperson asked me why. When I mentioned the Commodore 64, she said, “what is that?”. I was saddened.

But the book is more than just the history of Commodore, it’s also the history of the early days of personal computing, when a handful of people with vision and drive created an industry that previously didn’t exist. It was not the kind of industry like today, driven by salespeople saying “you need this”, trying to fulfill a need that doesn’t exist. Just the opposite, it was an industry built by people who saw a need that wasn’t being met, and designed products to meet those needs.

The book also illustrates that success in business is not always just drive and vision, but sometimes just pure luck. The best example given is that of VisiCalc, which was written on the Apple II, simply because the PETs were being used, while the Apple II sat idle. The PET version of VisiCalc came along later, but by that point, VisiCalc on an Apple II was the “killer app”.

Our current tech society clamors for new tech every six months, and products which over a year old are considered antiquated. But the 6502 drove a viable industry for more than 10 years, and it was not just Commodore that used it, Apple, Atari, Nintendo, and others also used the 6502.

If you look back on the 6502 today, you might scoff at its simplicity, but these people designed it _by hand_. I am not sure there are many of us today who can start at point zero, design a processor, and see that design thru all points of production until millions or perhaps even billions of them were produced. FPGAs and softcores don’t count for this exercise.

Lest you think this book is just a simpering adulation of Commodore, it is quite candid, discussing both their successes as well as their problems. I think my favorite quote from the book is, “The only people happy with Commodore were their end customers.”

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Posted By azog on December 28, 2011

The VIC-20 was the first computer I owned. I had used Apple II’s in the computer lab at school, but they were over $1,000, and simply unaffordable. So my parents got me a VIC-20 for Christmas one year.

So here are some pictures. There’s lots. Since the VIC-20 is special to me, I decided to do a video, too, which I’ll add at the end, but it basically repeats what I say here.

This has a “newer” style power supply, one with a round DIN connector. My original, long since lost, had one of the 2 prong AC bricks.

This is the user guide. This was a pack-in, and was pretty much an “intro to BASIC”.

My favorite feature of the users guide was VICMan, who appeared in various places.

The users guide shows the old style power input. I don’t know if there was a newer version of the users guide showing the respective power input. I acquired this users guide separately.

Later, they came out with the VIC-20 Programmers Reference Guide. It wasn’t as comprehensive as the Compute! “Mapping” series, but still it was extremely useful.

What made the Commodore Reference Guides special was their inclusion of a schematic. I know the Commodore 64 had a schematic, but I don’t recall if the Commodore 128 version did. I wouldn’t be surprised if it didn’t, as the C128 was significantly more complex.

And this schematic is also geared towards the old power supply. Again, I don’t know if a new version was released, but you can see the power supply is simply a 9VAC input. Rectifying was done on-board, and the fuse was actually in the brick, not on the board. The later versions were rectified in the brick, and the fuse was on-board. Almost the opposite.

When I received my VIC-20 for Christmas oh so many years ago, I also received a tape cassette drive. This is what I refer t as a “PET style” tape, since it was the same style that was sold on the PETs.

Later, the C64 style came out.

The different tape drives shared the same part number, the C2N. They’re functionally the same, but depending on your goal, you might want a PET style, or a C64 style tape cassette. There was also a charcoal grey version of the tape drive, but these were ONLY for the Plus/4, and incompatible with the rest of the line.

On every tape is a ground strap, which is useless on everything except a PET, since only the PET has a metal chassis. Don’t know why they continued to have it. Just cut it off…

Finally, to “complete” the set, I acquired a copy of Radar Ratrace!

And finally, a video of everything I talked about above, plus a short play session on Radar Ratrace.

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