{"id":21145428,"url":"https://github.com/etchedpixels/mini11","last_synced_at":"2025-07-23T11:05:41.607Z","repository":{"id":189124332,"uuid":"609933121","full_name":"EtchedPixels/Mini11","owner":"EtchedPixels","description":"A 68HC11 SBC for  the 68HC11A CPUs","archived":false,"fork":false,"pushed_at":"2023-03-08T23:06:54.000Z","size":557,"stargazers_count":11,"open_issues_count":0,"forks_count":6,"subscribers_count":4,"default_branch":"main","last_synced_at":"2025-07-02T06:44:03.177Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":null,"language":"Assembly","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"gpl-3.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/EtchedPixels.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null}},"created_at":"2023-03-05T17:06:48.000Z","updated_at":"2025-06-25T02:42:23.000Z","dependencies_parsed_at":"2023-08-18T11:44:27.827Z","dependency_job_id":"5e39e2ef-a170-44c8-b20a-7a1f6ef8ba74","html_url":"https://github.com/EtchedPixels/Mini11","commit_stats":null,"previous_names":["etchedpixels/mini11"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/EtchedPixels/Mini11","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/EtchedPixels%2FMini11","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/EtchedPixels%2FMini11/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/EtchedPixels%2FMini11/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/EtchedPixels%2FMini11/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/EtchedPixels","download_url":"https://codeload.github.com/EtchedPixels/Mini11/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/EtchedPixels%2FMini11/sbom","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":266665813,"owners_count":23964974,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","status":"online","status_checked_at":"2025-07-23T02:00:09.312Z","response_time":66,"last_error":null,"robots_txt_status":null,"robots_txt_updated_at":null,"robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":[],"created_at":"2024-11-20T08:40:17.346Z","updated_at":"2025-07-23T11:05:41.586Z","avatar_url":"https://github.com/EtchedPixels.png","language":"Assembly","funding_links":[],"categories":[],"sub_categories":[],"readme":"# Mini11: A Small 68HC11A System\n\nThe Mini11 is a small board that is designed to provide a complete large\n68HC11 environment with a fairly low chip count. It provides 16K of ROM and\n512K of RAM as well as breaking out all the spare I/O including the serial\nand SPI in useful ways.\n\nTo keep cost down it's designed to use the many old 68HC11A series parts\nthat can be found in junk boxes and old boards. This has a different pinout\nto the later processor variants.\n\n## Requirements\n\n- 68HC11A series processor (A0/A1/A8). 68HC811A probably works too\n- 512K SRAM\n- 27C256 or 28C256\n- 74HC(T)139\n- 74HC(T)00\n- 74HC(T)573\n- DS1233 reset controller\n- 8MHz crystal\n- pinheaders, sockets, resistors etc\n\n## Construction\n\nAs the 68HC11 can be serial bootstrapped it is possible to assemble the\nboard and fit all the discrete parts and only the 68HC11 into its socket.\nFit jumpers JP1 and JP2 and apply power. You should be able to talk to the\nboard with db11 or similar tools.\n\nIf you have a part with ROM then you should also be able to boot from the\nROM if you boot with JP1 and JP2 removed. If the ROM contains Buffalo as\nis usual then you will also need to jumper PE0 to ground. A 68HC11A8 with\nBuffalo should then produce a boot message and you'll be able to talk to\nthe monitor.\n\nThe boot mode can also be used to check out the board after the other parts\nare fitted. You can boot in single chip mode and then use db11 to turn off the\nsingle chip mode and then check that the memory is behaving. Port A controls\nthe memory banking. Bit 3 turns the ROM on and off, bits 4-6 are the memory\nbank.\n\nWith all the parts fitted you can burn firmware of choice into the ROM and\nwith the jumpers removed the chip should boot the firmware. Remember to use\nthe \".burn\" file with the provided firmware or the tools to flip bit 0 and 2\nas the board has D0 and D2 switched on the ROM\n\nThe provided firmware simply intializes the SD interface, loads the\nfirst sector and runs it.\n\n### Note\n\nYou cannot run an unmodified Buffalo from the ROM. It uses Port A pins for\ntracing and this conflicts with the memory banking.\n\n## ROM options\n\nFor a 27C256 you can load different firmware into each 16K bank and select\nusing JP3. For a 28C256 burn the firmware into the upper 16K and jumper JP3\nto VCC.\n\n## Rescuing Recalcitrant 68HC11A Parts\n\nIf you have problems with the 68HC11A such as it only coming up in bootstrap\nmode then there are a few things to check.\n\n### Wrong Config Byte\n\nIf the CONFIG byte is set to map in the internal ROM and the ROM contains\ngarbage or is absent (eg on a 68HC11A0/A1 part) then you can boot it into\nsingle chip mode and use db11 to change the config byte to 0x0C or similar.\n\n### Protected EEROM\n\nThe internal EEROM has protection options and some devices wih custom\nfirmware will set them. These can still be used as they will erase the\nEEPROM when the serial boot is triggered. This will put 0F into the CONFIG\nregister so that will also then need reprogramming.\n\n### Did You Remember D0/D2 Are Swapped In Your ROM Image\n\nNo.. opps\n\n## External Interfaces\n\n### J2: Serial (TTL Level)\n\nSimple three wire interface with no flow control. Usually run at 9600 baud.\n\n### J3: SPI (5v)\n\nSPI. Provides the expected SPI interfaces as well as two chip select lines,\nreset and the external IRQ (pulled up). Intended for an SD card and\noptionally additional devices with an SPI mux/demux board. Remember to use\nan SD adapter with voltage shifting.\n\n### J4: Power\n\n5v and ground, needs to be properly regulated. The board has an onboard\nreset generator to handle power coming up gracefully.\n\n## J5: GPIO\n\nThree input ports mapped to port A bits 0-2\n\n### J6: Analogue\n\nPort E of the 68HC11.\n\n## Jumpers\n\n### JP1: MODA\n\nFit the jumper to set MODA low\n\n### JP2: MODB\n\nFit the jumper to set MODB low\n\n### JP3: ROM Select\n\nSelect bank on 27C256, set to 5V with a 28C256\n\n## Software\n\nAt this point FUZIX. Build the \"mini11\" target, write the generated SD card\nimage raw to an SD card and boot the mini11 with it inserted. The console\nruns at 9600 baud.\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fetchedpixels%2Fmini11","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fetchedpixels%2Fmini11","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fetchedpixels%2Fmini11/lists"}