RTC ISA 8 bits (Very Low Profile)

Name: RTC ISA 8 bits (Very Low Profile)
SKU: 18898
Price: 11.95 USD
Availability: OutOfStock
Rating: 4.94 (12 reviews)

(12 Reviews)

Real Time Clock for PCXT and compatibles.

Designed by spark2k06 in Spain

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$11.95

Out of Stock

Sold out since Sep 03, 2023

Real Time Clock for PCXT and compatibles.

Description It is a project based on the SMBacker RTC but without Disk On Chip memory and a very low profile, which has the port mapped with these order options: 240h, 2A0h, 340h, 70h or other define…

Description

It is a project based on the SMBacker RTC but without Disk On Chip memory and a very low profile, which has the port mapped with these order options:

240h, 2A0h, 340h, 70h or other defined by the buyer.

The visible part after being inserted in the ISA slot is little more than the size of a 3V CR2032 battery as can be seen in the last photograph.

All discrete logic with an SPLD ATF16V8B, including the configuration of the port, thanks to which it can be reconfigured because the SPLD IC is into socket.

ISA gold fingers for greater signal reliability and board durability.

Why did you make it?

Sergey's micro8088 project lacks RTC unlike the other xi8088 project also designed by him. For this reason I decided to redesign the existing SMBacker project, removing the part of Disk On Chip that I consider unnecessary, and reducing the size of the board as much as possible.

What makes it special?

The small size is a differentiating element in this project, while maintaining the ease of welding in this second version when using throuth hole technology.

I have modified the micro8088 BIOS to make it compatible with it (version 0.9.7) on 70h port, and Sergey has optimized and improved the code. Until he decides to make it public in your GitHub repository, I leave it available in mine, as well as the instructions for its flashing:

0.9.7 RTC compatible and instructions

If your PC BIOS does not have support for RTC, you must use its management software, there are already several solutions for this purpose. However, after several tries it has been observed that these do not work properly. I suggest the use of the this application programmed by Alejandro Valero that has shown adequate operation:

COMMANDS (Default port 2C0h)

SETRTC.EXE - Update RTC from system date/time

GETRTC.EXE - Update system date/time from RTC

BATRTC.EXE - Check RTC battery status

All the commands allow a parameter with the port number that we want to use in decimal. So, to use it on port 240h, you must indicate parameter 576…

The best thing is that once you have it configured, add "get_RTC" to the autoexec.bat.

If your equipment is not a Micro8088, a recommended I / O port is 240h because it seems to be the one with the least conflicts.

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Review Breakdown

Average Ratings

Product: (5.00)

Documentation: (4.83)

Shipping: (4.92)

Communication: (5.00)

Hans | March 13, 2022

Works great in my IBM 5150

Works exactly as expected. Used the software suggested, pointed it at the correct port, and it just worked. Not having to type in the date and time on every boot is really nice, and this is one of the very few options for real-time clocks these days.

Response from spark2k06 | March 13, 2022

Thank you for purchasing this product and for this review.

Jason | Sept. 24, 2021

Amazing support and working great!

Using this in my "Micro 8088" aka NuXT. Was super easy to solder together. The Dallas Clock came pre-soldered. I had a small issue with the firmware and the battery holder but was able to get it quickly resolved thanks to great support from Aitor the maker and seller here.

If you have any issues with the battery showing up dead in the BIOS just bend up the bottom pin a bit so it presses into the battery better.

Really happy with my RTC. :D

Response from spark2k06 | Sept. 24, 2021

Thank you for purchasing this product and for this review.

Bruno | Sept. 12, 2021

Fantastic little add-on for retro PC XT computers

Great product, absolutely plug and play:
- Plug a battery into the card
- Insert the card in an ISA slot
- Start your PC XT
- Run "DATE" and "TIME" at the MS-DOS command prompt
- Then run "SET_RTC 576" (240h I/O port)
- Finally edit AUTOEXEC.BAT to add "GET_RTC 576"
And you are ready to go!

Response from spark2k06 | Sept. 12, 2021

Thank you for purchasing this product and for this review.

Terry | July 1, 2021

I taught my XT computer to tell time!

I installed the RTC module into an 8 bit slot on my Magitronic XT V20 IBM clone motherboard. I set the date and time using DOS' DATE and TIME commands. I then set the RTC using the command:

SET_RTC 576

Upon reboot I issued the command:

GET_RTC 576

and DOS updated with the correct date and time. It couldn't be easier. You must use the decimal value of the I/O address of the RTC card (576 = 240h) to both set and retrieve the date/time from the RTC card.

The RTC card does not come with a battery but it's easily found in any store as it uses the most common CR-2032 coin cell battery (the same battery used on motherboards for CMOS backup). Make sure you install the battery with the + side up.

If you're looking to add date/time features to your PC/XT/Clone then this little RTC card will do that for you. I highly recommend!

Response from spark2k06 | July 1, 2021

Thank you for purchasing this product and for this review.

Nicolas | May 17, 2021

Just what my Tandy 1000 needed!

I bought one for my Tandy 1000TX, got it configured for 240h and works great with the suggested software. I used Brutman's mTCP suite with SNTP to set exact Internet NTP date and time then update the RTC, now my clock is always correct, a very nice to have addition to my retro setup!

Response from spark2k06 | May 22, 2021

Thanks for this review!

Alex | April 27, 2021

Great product, personal service - amazing seller!

Very well made RTC board for a retro XT computer. Seller was very accommodating and went above and beyond with finding the right solution for my system. Great product + Exceptional service + Lighting-fast shipping! 5 STARS!!!

Thank you!

Response from spark2k06 | April 27, 2021

Thank you for purchasing this product and for this review.

Darren | March 22, 2021

Literally plug in and go

If you're using this with the Micro 8088 platform then it easily adds the missing RTC functionality. Just plug it into an ISA slot and you're done. In my case I bought the RTC and micro 8088 board from here and haven't been disappointed. Delivery was quick and service very responsive.

Response from spark2k06 | March 22, 2021

Thank you for purchasing this product and for this review.

Nils | Nov. 19, 2020

Great real time clock for a XT

Though I miss some decoupling capacitors on the board, it works like a charm. Feels so great not to have to enter date and time again and again and again. Great product, highly recommended!

Response from spark2k06 | Nov. 19, 2020

The board is so low profile that I have not considered adding decoupling capacitors, because presumably you will already have them very close in the motherboard itself. In any case, thanks for the suggestion, for this review and for the purchase of the product.

Miodrag | Nov. 2, 2020

Nice little board

If you own Micro 8088 then you need this board. Board is very simple in design and can be easy update to work under different address (you need programmer capable of handling GAL chips). Being low profile makes it bit hard to pull out, but it lower the cost.

Response from spark2k06 | Nov. 2, 2020

Thank you for purchasing this product and for this review.

Jason | Aug. 25, 2020

Niche product does the job. Some technical hurdles.

The RTC board works like a champ after some technical support to get it working with my IBM 5155. Get the specific RTC program for it as well (just ask, you'll get links). Works like a champ now. port 70h wouldn't work with mine. It would just lock up. Port 240h works perfectly. No more need to type in date and time at each boot. Just run the RTC program to get the time from autoexec and go. I wish more companies were this helpful.

Response from spark2k06 | Aug. 25, 2020

Thank you for purchasing this product and for this review. Initially the project was intended to work on port 070h because it was intended for use with Sergey Kiselev's Micro8088 clone, however it can be a conflicting port in other clones, for which 240h is a perfect I/O port.

Thorsten | July 31, 2020

Works fine in a Commodore PC10-II XT-Clone from 1986

I just came back from holidays and found this little package from Spain.
After some juggeling around with the jumpers for the hardware interrupts of all the other cards (MFM, Sound, XT-IDE), I first thought I got it running with CLOCK.COM from David_M.(http://www.minuszerodegrees.net/rtc/david_m/CLOCK.zip) as it was suggested in the forum.
BUT: If I don't use the "forced" mode to port 70h CLOCK.COM would freeze my machine.
AND: With forced mode I could only read and write date and time from DOS to RTC, but the RTC would not "tick". It always kept the same hour, minute and seconds.
I wasn't able to determine the cause of that behaviour.
I mailed Spark2k06 about this problem and he patietnly and friendly looked into my problem and provided then a "handwritten" alternative "driver programm" via mail, where you can set the port manually.

This soultion now works perfectly fine!!! :-)

I was looking for this kind of extension card for quite a while.
Thanks a lot for the hardware and the friendly support

Response from spark2k06 | July 31, 2020

Thank you for purchasing this product and for this review. There are those who have problems with port 70h due to conflict with some element of their machine, but thanks to the SPLD it is possible to configure it on any other I/O port.

Kheng Meng | April 26, 2020

Very responsive and helpful seller

Product is a nice addition to systems which only need an RTC. Most other RTC boards are integrated with other functions which you may or may not need and thus you pay for unused features.

With this board, if you need an RTC only, this is the best product for you.

I initially had some issues with using the product with my IBM 5155. Thanks to spark2k06 for the responsive help of spark2k06, I could get it to work.

Do also checkout the vcfed link for details. http://www.vcfed.org/forum/showthread.php?71958-RTC-ISA-8-bits-(Very-Low-Profile)