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View Full Version : Silver TI99/4 with PEB spotted



toro
November 24th, 2009, 01:35 PM
I've seen a weird TI99/4 this afternoon, it had a HUGE expansion device the size of an XT machine, it was a tower with a 2-bay large 5.25 floppy drive and bays below to accomodate several cards.

The person is asking $50 for everything, I might pick it up tomorrow.

It looks just like this :

http://upload.wikimedia.org/wikipedia/commons/d/d8/TI99expansion.jpg

Are PEB's sought by collectors ? Or is it something common ?

Thanks guys.

minty
November 24th, 2009, 02:16 PM
The PEB isn't common - old computers (http://oldcomputers.net/ti994a.html) reckons 250,000 PEBs were sold for 2.5 million TI99s, and to be honest, I'm suprised it's that many.

Not sure how collectable they are, although personally I'd love one! I think it's one of the coolest looking expansions systems of the 80s.

VintageComputerman
November 24th, 2009, 02:48 PM
They were going for around $50.00 to $85.00 bare. More with hard drives, floppy's, etc. I have two right now and I was lucky to find them in such good condition.

I also have spare parts and a lot of other controller cards, voice, printer interface, etc. They were of industrial design back then, especially the cables. That's why they look so weird.

You got a good find at a great price, imo.

Ksarul
November 24th, 2009, 05:34 PM
Definitely a good buy, as you mentioned it had dual drives in the bay. That would indicate that it probably has the disk controller card (would be close to the end with the drives) along with the flex cable interface (this latter object has that big flat cable connected to it).

Once you add in shipping, you'd pay at least twice that from eBay. If it has one of the third-party disk controllers (as opposed to the one from TI), the price would be even higher, as they often go for $100-$150 each. There are still a few folks out there who repair bad cards too, on the off chance that any problems arise.

geoffm3
November 30th, 2009, 10:46 AM
The PEB made the 99/4A into a usable computer. The base machine is quite crippled, with only a few bytes (no typo) of system memory for the register set, stack and working variables. Most cartridge software relied on slow access to video ram for program storage, using a language called GPL (graphics programming language). The Expansion box let you put up to 32k (from TI) on the CPU bus to use. Back in the day I had a 128k memory expander from a third party in mine. It would at least let you use the additional memory as a RAM disk. Don't know if any programs existed to allow you to bank switch, but I wouldn't be surprised.

When you get it home, pop open the case and tell us what cards you find. You'll really enjoy the 99/4 a lot better with it to be sure.

channelmaniac
November 30th, 2009, 01:11 PM
Exactly... 2 x 6810 SRAMs... 128 bytes each. Two of them gave the 16 bit CPU a whopping 128 words of memory.

To access the 16K of memory you had to go through a 16 to 8 bit glue chip THEN go across the VDP to get to it. It was SLOW...

To add insult to injury they used cheap GROMs which were VERY odd 1 bit ROMs. You could just about add with a calculator faster than the TI BASIC could do it thanks to those silly GROMs.

Sigh. What companies are willing to do to save money (or keep from affecting sales of higher end products) just boggles the mind.

geoffm3
November 30th, 2009, 01:17 PM
Exactly... 2 x 6810 SRAMs... 128 bytes each. Two of them gave the 16 bit CPU a whopping 128 words of memory.

To access the 16K of memory you had to go through a 16 to 8 bit glue chip THEN go across the VDP to get to it. It was SLOW...

To add insult to injury they used cheap GROMs which were VERY odd 1 bit ROMs. You could just about add with a calculator faster than the TI BASIC could do it thanks to those silly GROMs.

Sigh. What companies are willing to do to save money (or keep from affecting sales of higher end products) just boggles the mind.

Yeah, IIRC the GROMs were serial clockable ROMs, so random access isn't possible... you have to step through to the address you want. I could be wrong about that though. :)