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# RTC8088
Real Time Clock for your PC XT. Very low profile, simple and open hardware.
## Hardware Documentation
### Schematic and PCB Layout
[Schematic - Version 3.0](KiCad/RTC8088-Schematic-3.0.pdf)
[PCB Layout - Version 3.0](KiCad/RTC8088-Board-3.0.pdf)
### Swiches and Jumpers
#### SW1 - RTC I/O address select
I/O Address | SW1.1 | SW 1.2 | SW 1.3
------------ | ----- | ------ | ------
0x70 | OFF | OFF | OFF
0x240 | ON | OFF | OFF
0x2A0 | OFF | ON | OFF
0x2C0 | ON | ON | OFF
0x340 | OFF | OFF | ON
0x3A0 | ON | OFF | ON
0x3C0 | OFF | ON | ON
Reserved | ON | ON | ON
* Note 1: The table above gives the addresses in the supplied SPLD fuse map. The selection can be changed by reprogramming the SPLD
* Note 2: "Reserved" address is set to 0x70 in the supplied SPLD fuse map. It is recommended to use this setting when adding a custom I/O address to the SPLD
#### JP1 - Clear CMOS
Position | Description
-------------- | -----------------
open (default) | Normal operation
closed | Clear NVRAM memory
### Bill of Materials
#### Version 3.0
[RTC8088 project on Mouser.com](https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=2877d21cfa) - View and order all components except of the FDC and the PCB.
[RTC8088 on OSH Park](https://oshpark.com/shared_projects/bAF8uwKL) - View and order the PCB.
Component type | Reference | Description | Quantity | Possible sources and notes
------------------ | --------- | ----------------------------------------------- | -------- | --------------------------
PCB | | RTC8088 PCB - Version 3.0 | 1 | Order from your favorite PCB manufacturer using provided Gerber files
Integrated Circuit | U1 | DS12885+ - RTC, 24 pin DIP | 1 | Mouser [700-DS12885](https://www.mouser.com/ProductDetail/700-DS12885) or [700-DS12885N](https://www.mouser.com/ProductDetail/700-DS12885N)
Integrated Circuit | U2 | ATF16V8B-15PU - Simple Programmable Logic Device, 20 pin DIP | 1 | Mouser [556-AF16V8B15PU](https://www.mouser.com/ProductDetail/556-AF16V8B15PU) or GAL16V8
Quartz Crystal | Y1 | 32768 Hz, 6 pF | 1 | Mouser [815-AB26T32768KHZ6B](https://www.mouser.com/ProductDetail/815-AB26T32768KHZ6B), [520-ECS327-6-13-X](https://www.mouser.com/ProductDetail/520-ECS327-6-13-X), or [628-VT200F-6PF20PPM](https://www.mouser.com/ProductDetail/628-VT200F-6PF20PPM)
Battery Holder | BT1 | CR2032 battery holder | 1 | Mouser [122-2620-GR](https://www.mouser.com/ProductDetail/122-2620-GR) or [122-2420-GR](https://www.mouser.com/ProductDetail/122-2420-GR)
Battery | BT1 | CR2032 battery | 1 | Mouser [81-CR2032](https://www.mouser.com/ProductDetail/81-CR2032), [658-CR2032](https://www.mouser.com/ProductDetail/658-CR2032), or [614-CR2032-200](https://www.mouser.com/ProductDetail/614-CR2032-200)
Capacitor | C1 | 0.1 uF, 50V, MLCC, 5 mm pitch | 1 | Mouser [594-K104K15X7RF53H5](https://www.mouser.com/ProductDetail/594-K104K15X7RF53H5) or [810-FG28X7R1H104KNT6](https://www.mouser.com/ProductDetail/810-FG28X7R1H104KNT6)
Resistor Array | RN1 | 10 kohm, bussed, 5 pin SIP | 1 | Mouser [652-4605X-1LF-10K](https://www.mouser.com/ProductDetail/652-4605X-1LF-10K) or [652-4605X-AP1-103LF](https://www.mouser.com/ProductDetail/652-4605X-AP1-103LF)
DIP Switch | SW1 | DIP switch, 3 position, SPST | 1 | Mouser [774-2103MS](https://www.mouser.com/ProductDetail/774-2103MS)
Pin Header | JP1 | 2 pin header, 2.54 mm pitch | 1 | Mouser [649-68002-102HLF](https://www.mouser.com/ProductDetail/649-68002-102HLF)
Jumper | JP1 | Shunt, 2 pin, 2.54 mm pitch | 1 | Mouser [806-SX1100-B](https://www.mouser.com/ProductDetail/806-SX1100-B)
IC Socket | U1 | 20 pin DIP, 2.54 mm pitch, 7.62 mm row spacing | 1 | Mouser [649-DILB20P-223TLF](https://www.mouser.com/ProductDetail/649-DILB20P-223TLF)
IC Socket | U2 | 24 pin DIP, 2.54 mm pitch, 15.24 mm row spacing | 1 | Mouser [649-DILB24P-223TLF](https://www.mouser.com/ProductDetail/649-DILB24P-223TLF)
## Software
The board is supported by the [8088 BIOS](https://github.com/skiselev/8088_bios) and [GLaTICK BIOS Extension](https://github.com/640-KB/GLaTICK).
## Release Notes
### Changes
* Version 3.0
* Add I/O address configuration switches
* Remove IRQ configuration jumpers and IRQ support
* Version 2.0
* Aitor RTC8088
* Version 1.0
* Initial version
### Known Issues
* No known issues
### Wishlist
* None so far
## Red Tape
### Licensing
RTC8088 is an open source hardware project. The hardware design itself, including schematic and PCB layout design files are licensed under the strongly-reciprocal variant of [CERN Open Hardware Licence version 2](license-cern_ohl_s_v2.txt). The SPLD code is licensed under [GNU General Public License v3](license-gpl-3.0.txt). Documentation, including this file, is licensed under the [Creative Commons Attribution-ShareAlike 4.0 International License](license-cc-by-sa-4.0.txt).
## More information
### Orignal RTC8088 Project Description
https://hackaday.io/project/168972-rtc-isa-8-bits-pcxt
d079aeb57This file is pinned to the selected release. Download the original to open it in your design tool.