Month: February 2014

Adventures in Retrocomputing: Troubleshooting a GS-RAM Plus

Brent Retrocomputing, Technology Leave a comment

One of the outstanding items on my IIGS checklist has a bigger RAM card, because while 4mb is nice, I want to be able to push this thing to its limits. Fortunately, I’ve recently come a bit closer to completing the checklist. I sourced a 6MB Applied Engineering GS-RAM Plus for about $100 – a very reasonable price for a card like that, especially considering that the seller said that the card was tested to be in good working condition.

So, I bought the card, got it home and tried it in my IIGS – no luck. A little bit of research suggested that a GS-RAM plus would not work correctly on a ROM 03 IIGS if it had the 1A version of the GAL instead of the 1B version. This one, of course, had the 1A version. So, I popped it out, pulled my ROM 01 IIGS out from under the desk and tried it on that one. No luck there either. Got the same “checkerboard” screen on both machines, which can apparently indicate RAM or CPU problems, improperly seated chips, or a bad add-in card. Since the machine was working both before I installed the new RAM card, and after I took it out, I figured that it must be the culprit. So, I took a closer look:

m_45738_1As you can see, the chip right above the connector, on the left, has a hole in it. (This is the eBay seller’s original picture, so it must have happened in between the testing and the listing.) That, to me, looked like a likely culprit.

So, I contacted the eBay seller, asking their permission to try and fix the problem myself before returning the card (recycledgoods.com – they were an absolute pleasure to work with) and set out to find a replacement chip. Fortunately, just about every chip on that card is socketed (a nice feature of late 80’s technology), so it would be easy to replace.

The trick, of course, is finding the right one. The hole was right in the middle of the model number on the chip, rendering the middle two characters unreadable – so I had to find another source of information. The product manuals were of no help, being mostly concerned with how to install the card. So, the next best option was to find a picture of the card (which appears to have gone through a couple of revisions) in a high enough resolution that I could read the model number off the chip. I busted out a little Google-fu, and eventually found this image kindly uploaded by the folks over at ReactiveMicro:

GS-RAM Plus - 6 Meg Board ShrunkFortunately, it was a GS-RAM Plus of the correct vintage, and the picture was high enough resolution to make a positive identification of the chip (The full sized picture is huge! 6068px × 2028px and 10MB – it was easy to read the fine print on all of the chips).

Now that I had a model number, the next step was to find out what the chip actually did. Fortunately, it was an off the shelf part (made by Samsung) and Google makes finding datasheets easy. With the datasheet in hand, I was able to determine that it was designed to be used in “implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers.” Or, in other words, it would not contain any custom program logic or configuration, so can be easily replaced.

Fortunately, these are still readily available, so I checked out a few chip suppliers. Unfortunately, they all wanted me to buy in quantity, so it was back to eBay. I tracked one down for $1.78 plus shipping and had it sent out. It got here a few weeks later, arriving last night, and I swapped it out, plugged the card into the IIGS, and everything booted up just as expected.

It’s always nice when the problem ultimately turns out to be simple, even if it takes a bit of Internet spelunking to figure out the details!

Building a Baby Monitor

Brent Technology 1 Comment

For our son, we have a video baby monitor mounted over his crib so that we can keep an eye on him while he is sleeping. This way we can tell if he is tossing and turning, or if he is actually asleep. This is something that we have gotten very used to, and perhaps even spoiled by. When we are visiting his Grandparents, for example, and he is supposed to be napping in his playpen in the other room, he often doesn’t want to go down nicely. We can hear him if he cries, but if he is quiet, can’t tell if he is actually asleep. So, we wanted a video monitor that we can take with us when we travel.

His regular monitor is mounted to the wall, so we can’t easily take it with us, and a new monitor is fairly expensive – at least relative to how much we would expect to use it. So, I had to come up with another solution. Being a technical person, I have bins full of old, cast off and left-over parts, including about a half-dozen routers, and a couple IP cameras left over from an old project.

So, I pulled one of the routers, and one of the IP cameras – a TRENDnet TV-IP422W.

TV-IP422W_a1It’s a few years out of date, and only supports Wireless-G, and 640×480 video at 30 FPS, but the price is right. Not to mention, this camera has Pan/Tilt/Zoom, infrared night vision, a microphone, and an iPhone app – perfect for use as a baby monitor!

Unfortunately, while the camera does support ad-hoc wireless networking, it only supports WEP “security”. So, to make sure that we have a reasonably secure wireless network, I need to pack along the router as well. And, since I needed to use the router anyways, I figured that I would just connect the camera using the wired connection. It is significantly quicker, and I have always had trouble getting a decent frame rate from the camera over wireless. It also means that I can connect to the router using Wireless-N instead of Wireless-G.

So, after a bit of grief requiring me to set everything back to factory settings on all the devices, (That’s what happens when you use devices for various projects and just throw them back into the box without resetting them first), I plugged the camera into the router, configured a network with the necessary security settings, and connected up my old iPhone, which will be pressed into service as a monitor station when we travel.

It works great! just goes to show you what you can do when you have a few boxes of old parts lying around and can do a little bit of creative thinking.

EDIT: Forgot to add, you need to get the TRENDNet SecurView Mobile application off iTunes to support these old cameras. The TRENDnet SecurView Pro app only supports the newer ones. Both apps are free though.