Identifying a Mystery ISA Card

Gregory Beat w9gb at
Fri Oct 16 13:15:21 CDT 2020

Sean, Fred, and Glen —

Sorry, late to this ISA card thread.
I worked in Tech Support for an Apple/IBM/HP/Novell retail computer dealer,
during summers in early 1980s, when in Graduate school. 
So I saw the “wide selection” of add-in cards for IBM PC/XT and compatibles.
This is a “Taiwanese generic 6-Pak” Add-In (8-bit ISA) expansion card.
RAM 384 kB; Serial port, Parallel port, Game port, AND Real Time Clock !

Glen is CORRECT, the National Semiconductor MM58167 is the RTC IC.
Texas Instruments bought out National in 2011, data-sheet still available.
The “solder-in” B1 battery has been cutout (open space below/left of MM58167).

Replacement battery (likely ~ 3 to 3.6 Volt) can be acquired from Digi-Key. 
Take measurements and closeup photo of “B1” Area, to CONFIRM Model and Size.
My Quick Guess ?
Tadiran TL series 1/2 AA with Axial pins, 3.6V High Capacity Cylindrical battery
Tadiran TL-5902/P .... $6.65

greg, w9gb
Date: Thu, 15 Oct 2020 17:34:58 -0700
From: Glen Slick <glen.slick at>
To: "General Discussion: On-Topic and Off-Topic Posts"
   <cctalk at>
Subject: Re: Identifying a Mystery ISA Card

On Thu, Oct 15, 2020, 5:24 PM Fred Cisin via cctalk <cctalk at>

>> On Thu, 15 Oct 2020, Sean Ellis via cctalk wrote:
>> I got this (currently exploded) mystery RAM, RTC, and I/O board out of
>> a dead Sanyo luggable the other night, and once I replace the burned
>> up tantalums I'd like to put it in my 5150 so I can get a full 640k of
>> RAM.
>> Question is, does anyone know what this board is? It's a completely
>> anonymous board with not even an FCC ID to go off of. I'm assuming the
>> RAM is at least strapped right; all the banks are full which should be
>> 384k, and the Sanyo was a 256k machine = 640k.
>> Here's a couple pictures; one's an actual picture of the card and the
>> other is a simplified TULARC/TH99-esque vector of what's on the board.
> It resembles, although doesn't match, the AST Six-Pack.
> But the AST Six-pack had a clock circuit.

Isn't the 24-pin DIP part number MM58167 ,shown in the images referenced above,
an RTC chip?

More information about the cctalk mailing list