Replacement for potted ATD-20 combo RTC/battery IC?

[natevw]

My original Tandy 1000 has an extended memory plus wall clock ISA card, board model T512CLK-A1 by "A.T.D. INC Sunnyvale, CA". On it is a part labelled ATD-20 Clock/Calendar, 20 Year Battery.

Well it's been more than twenty years and the battery seems not to help it keep accurate time anymore.

I went to go swap out the battery, but on closer inspection it's actually a whole 28-pin chip/daughterboard. The bottom shows signs of the thing being potted; a hard and shiny black epoxy that gives off a "might not soften under heat" vibe.

Does anyone know what's inside of this part? Would it be relatively simple to swap it out for some underlying/compatible real time clock IC and wire in my own battery hookup?

The huge thread at http://www.vcfed.org/forum/showthre...d-for-the-Tandy-1000-line&p=551930#post551930 mentions this card model and then goes on to say:

I had to perform "surgery" on the Smartwatch chip on my HX when it's batteries finally died.

Looks like that chip (sold by Tandy for other computers) was a DS1216E, which at least has 28 pins but was meant to stick between a ROM chip and various TRS-*) motherboard. Not sure if that would be a likely candidate on this IBM compatible style ISA board then :-/

 

[modem7]

Does anyone know what's inside of this part?

Based on your next question, I think that you are asking for low level information, i.e. part number of IC, and type of battery/ies. Hopefully someone will post some factual information on the ATD-20 part.

Would it be relatively simple to swap it out for some underlying/compatible real time clock IC and wire in my own battery hookup?

Unless someone identifies the IC in the ATD-20 part for you, it may be you using a Dremel type tool finding out.

If you 'dremel' through the ATD-20 from the top, you may discover that the battery is in the top half of the ATD-20, in which case, it should be relatively easy to disconnect the battery and wire in a replacement.

Well it's been more than twenty years and the battery seems not to help it keep accurate time anymore.

Because you have the clock software that supports the ATD-20 part, it is possible that disassembling the clock software may reveal the IC (or a compatible one). For example, at [here], member Maelgrum disassembled some of the clock software to see which chip type (and at which port/s) the software was seeking.

 

[natevw]

Disassembly may be the way to go. My usual tool for present day RE work (Hopper.app) seems up for the task [UPDATE: maybe not, I don't think it's dealing with 16-bit addresses correctly] with some manual massaging, and knew about the 0100h offset before I did…. Unfortunately it looks like there's a lot of JMP/CALL/MOV stuff going on beyond the small COM file itself that I will have to track down (DOS? BIOS? incorrect disassembly?)

I'm hesitant to destroy the chip itself since it's at least somewhat working, even though it can't keep time well when powered off. Maybe someone more adventurous has taken one of these apart already? My assumption is that ATD did not have their own ASIC and there's something a bit more common inside, though I could be wrong as I don't know much about the company.

 

[Chuck(G)]

I suspect that there's a Dallas chip (or a clone) under the hood. Are all pin positions populated, or are some vacant (i.e. internally terminated)?

 

[modem7]

natevw supplied the clock software, and I have hosted it at [here].

 

[rkrenicki]

So, this is a bit of an old thread, but I just finished duplicating the T512CLK board. I can say that the RTC chip only has 6 connections to it. I would suspect that it is a variant of the Dallas Smartwatch, given the very low active pin count.

 

[drdoc]

So, this is a bit of an old thread, but I just finished duplicating the T512CLK board. I can say that the RTC chip only has 6 connections to it. I would suspect that it is a variant of the Dallas Smartwatch, given the very low active pin count.

I have an ATD "TMUL 512+", an 8-bit ISA board, with the same ATD-20 module mounted. Looking at this datasheet, I think you're right. If it's a 28-pin "Intelligent Socket", my board has VCC, VCCb, GND, WE, OE, CE, and DQ0 connected.

The battery's dead dead dead, so I'll probably dissect it soon.


Doc

 

[MGaddict]

I have an ATD "TMUL 512+", an 8-bit ISA board, with the same ATD-20 module mounted. Looking at this datasheet, I think you're right. If it's a 28-pin "Intelligent Socket", my board has VCC, VCCb, GND, WE, OE, CE, and DQ0 connected.

The battery's dead dead dead, so I'll probably dissect it soon.


Doc

Did you ever dissect it? I'm curious. I'm trying to resurrect a 1000 and a 1000SX. Both have serial boards/ram expansion/RTCs on them and they all have this ATD-20 Clock/Calander chip that is dead.
If somebody else didn't figure out how to bodge something together, I guess I'll be the test rat.

 

[hornbetw]

According to here, it is a DS1216B or C. that suggests that the many webpages showing how to replace batteries on those modules should apply to these modules also.