• Please review our updated Terms and Rules here

Tandy 1200 Memory Upgrade

zombienerd

Veteran Member
Joined
Mar 31, 2017
Messages
558
Location
New Hampshire
I have a Tandy 1200 coming in on Thursday, and it only has 256k on board. There doesn't seem to be much information on this model out in the wild, besides an article or two about it. One such article claims you can expand to 640k on board. I'm wondering which chips should I be hunting for, or should I just try to find an ISA expansion card (like the AST Six Pack).

The machine has dual floppies, no HDD. I plan to upgrade the machine to VGA, get ram up to 640k (or higher, if capable), and add an XT-IDE card eventually. Perhaps an NEC V20 chip in the future as well.
 
Send some pictures of your motherboard when it arrives. They came in at least two flavours if memory (pardon the pun) serves. 5 slot and 8 slot. It's possible the 8 slot can be upgraded to 640K on the motherboard.

I have to consult old RSCC catalogs but I recall it was released initially as the T1200 HD (with a 10Mb HDD) then later on augmented the series with a dual floppy drive version.

I'm prepared to be proven wrong on all these statements.

Ian.
 
I wasn't aware there were two flavors. This is a 7 slot motherboard with two banks of soldered on DRAM chips - assuming 128KB per bank. There are no free DIP sockets unless they are under the floppy drives.0806171927c_HDR.jpg
 
Yeah I mean 7 slot. :)

I checked RSCC catalogs site and the entries for T1200 HD in 1985 and 1986 refer to the 5 slot versions. There is nothing in 1987 re. the T1200. No mention of the dual drive non-HD T1200 anywhere so it must have been a special order product or Tandy wanted to keep quiet about it lest it stole too many sales from the T1K.

I need to find some T1200 SMs and have a read.

Ian.
 
Ah yes, good memory. The only service manual I have only shows a 5-slot version. I don't see it on-line. I could have a go at scanning it, however it's a hard glue based binding. It would have to essentially destroy it to properly scan it. If it's not online anywhere, I'll try.
 
Actually I am wrong again. In the User's Guide, it states the main board can be upgraded to 640K. Fill sockets U79 -> U87 and U100 -> U108 with 256K chips. Then S1-3 and S1-4 must be OFF. Jumper JP1 to 'B' position.

I'll take a post some photos of the manual
 
Picked up an 8 Bit Western Digital (Paradise) VGA card + Winbond Serial / Parallel / Game card.. They're untested, but I'm hopeful. I got them for $25 + shipping for the pair, not a bad score IMHO, and not a lot of cash to lose if they turn out to be bad. Sometimes you actually don't feel ripped off when finding stuff on eBay.

Now is the hard part, waiting for everything to arrive. I know the machine boots as it is, so I'll test the VGA card first, then the serial/parallel, then the new RAM.

Fingers crossed for a fully functional box when I'm done plugging new stuff in :p
 
Did anything come of this? I'm looking to upgrade my 1200 as well.

I am the thing I hate the most... Never finishing the story!!

Yes, the RAM upgrade worked perfectly. The machine now has an XT-IDE, 8-bit Soundblaster CT1320, and the WD Paradise video card (on/off with a Graphics Gremlin card I built, it's the perfect machine for testing).

Looks like the Jameco link is still active, so you should be able to pick up 18 of them and be all set!
 
Did you have any issues desoldering the old chips? What are you running on it? I was thinking of putting windows 2.x on mine.
 
Back
Top