68kMLA Classic Interface
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| Macintosh SE/30 M5119 - Restoration | |
| Posted by: GreenBar0n on 2025-02-15 20:55:28 The Pin Matrix Data chart insists pin N is the last pin of UK8, the CPU. The Pin Matrix chart lines up correctly if you ignore there are only (13) pins, and pretend the last one is N. | |
| Posted by: GreenBar0n on 2025-02-15 21:47:27 Made it through the Data Pin Matrix, all pins and continuity check out. Need to put this back together, and start looking for reset and clock signals. Do have an ATX extension cable. https://www.amazon.com/dp/B07L88HJ9X | |
| Posted by: GreenBar0n on 2025-02-16 12:30:07 At least I didn't make it any worse.  Need to check the Reset and Clock lines today. Is there a way to check the ROM without a spare or replacement? | |
| Posted by: GreenBar0n on 2025-02-23 11:17:11 Rather than try to visually inspect this board for broken traces, it's time for a diagnostics program. In this episode of Adrian's Digital Basement: he uses a modem cable (8-pin to 25-pin), converted with Laplink cables, to connect to a PC's DB9 port with Terra Term - in order to obtain error codes for a pre-ROM boot (simasimac SE/30 board). With the Poor-Man's Tech Step, he's able to decipher the error code, and locate the broken chip/trace with the info obtained. Rather than going through all those conversions of cable's, would it be possible to use just an 8-pin DIN, that goes straight to DB9, such as this cable? 
6ft APPLE IIGS Printer Cable Mini DIN 8 Male to DB9 Female - Gray | eBayThe APPLE IIGS Printer Cable Mini DIN 8 Male to DB9 Female is a reliable and efficient connection solution. With its Mini DIN 8 Male and DB9 Female connectors, it seamlessly connects your APPLE IIGS computer to supported printers. This cable is designed to deliver a stable and high-speed data...
www.ebay.com
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| Posted by: croissantking on 2025-02-23 12:08:17 I just used a standard Apple serial cable (with DIN-8 on both ends) and hooked it up to my Macintosh IIci running Zterm. | |
| Posted by: GreenBar0n on 2025-02-23 13:35:29 I have a good SE instead of a IIci, would an SE and Zterm work, with the same cable you used? | |
Posted by: croissantking on 2025-02-23 14:00:03I have a good SE instead of a IIci, would an SE and Zterm work, with the same cable you used?Probably, I don’t have any 68000 Macs but I’m sure they could handle a bit of terminal emulation | |
| Posted by: GreenBar0n on 2025-02-23 16:43:19 I have plenty of good DB9 capable PC's here. Just can't determine if that 8-pin Apple printer cable would line up with the correct DB9 output, or RS-232 COM port input. A null modem adapter might be necessary to cross the Tx and Rx between terminals, in order to get that to work. | |
| Posted by: nathall on 2025-02-23 21:10:58 I can confirm this works. I believe Apple printer cables are nulled by default. I used one to connect my Macintosh Plus with Zterm to my IIfx to access the diagnostics mode a few years ago. The problem that I had wasn’t the connection— there is virtually no documentation that I could find on the actual diagnostics commands and the responses. Apparently different ROMs have somewhat different command and reply sets. I could never make much sense of what information I was getting. But, it does work. | |
| Posted by: GreenBar0n on 2025-02-23 22:24:01 Great to hear that cable works, I'll get the 8-pin DIN to DB9. Thanks! Here's the spreadsheet Adrian prepared with the commands for terminal access to the pre-ROM boot: https://docs.google.com/spreadsheet...LH6ruCiAVE/edit?gid=1499087781#gid=1499087781 He also includes assembly code that tests the video ram. Going to get that cable and see what I can find. | |
| Posted by: nathall on 2025-02-23 22:29:46 Sorry, I should have been more clear: DIN8 to DIN8 printer cables work. Plus and IIfx both use DIN8 serial ports. Thanks for that document regarding the diagnostics. It’s probably time I tried it again, as my IIfx still does not live. | |
| Posted by: GreenBar0n on 2025-02-24 11:31:27 You're welcome! And thanks to Adrian for putting the spreadsheet together. Found an 8-pin to DB9 that claims to be RS-232. Already have a USB to DB9/COM port that will connect to this. https://www.ebay.com/itm/184211248546 The cable was shipped this morning, should have it by this weekend. | |
| Posted by: djc6 on 2025-02-24 20:08:30 I’ve done the poor man’s tech step on my SE/30 using DB9 to DIN-8 cable I made for use with ADTPro on my Apple IIGS. Here is the pinout: It’s wired as a null modem. I used an old DIN8 to DIN8 cable, cut one end off and attached a DB9 breakout board: | |
| Posted by: GreenBar0n on 2025-02-24 22:08:37 Nice work! What are you using on the DB9 end to talk to the SE/30 board with? Have you been able to retrieve any useful info from it? | |
| Posted by: Fred1212 on 2025-02-26 20:36:50 This is probably a very good candidate for a reloaded board. Caymac? | |
Posted by: joshc on 2025-02-27 00:19:26The problem that I had wasn’t the connection— there is virtually no documentation that I could find on the actual diagnostics commands and the responses. Diagnostic Mode - mac68k - Confluence | |
Posted by: djc6 on 2025-02-27 11:48:01Nice work! What are you using on the DB9 end to talk to the SE/30 board with? Have you been able to retrieve any useful info from it? I was running CoolTerm on a 2018 mac mini running macOS Sequoia Roger Meier's Freeware
freeware.the-meiers.org
Using this USB to DB9 adapter - I like it because its 6ft long, so between the adatper and the null modem cable I could have the SE/30 on bench across room Amazon.com: UGREEN USB 2.0 to RS232 DB9 Serial Cable Male A Converter Adapter with FTDI Chipset for Windows 10 8.1 8 7 Vista Linux and Mac OS X 10.6 and Above 6FT : ElectronicsBuy UGREEN USB 2.0 to RS232 DB9 Serial Cable Male A Converter Adapter with FTDI Chipset for Windows 10 8.1 8 7 Vista Linux and Mac OS X 10.6 and Above 6FT: Cables & Interconnects - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
I see its no longer for sale, but other 6ft adapters exist. I was able to execute code on the CPU using TechStep commands - that made me focus on video circuit, it ended up being UG8. I wrote about my troubleshooting here: https://68kmla.org/bb/index.php?thr...king-to-no-video-does-chime-on-startup.48851/ | |
Posted by: GreenBar0n on 2025-02-27 14:51:14This is probably a very good candidate for a reloaded board. Caymac?I've got to try to fix this stock board, if all else fails the Reloaded board is a great option. I was running CoolTerm on a 2018 mac mini running macOS Sequoia Gives me some hope this can be a useful tool. Thanks. | |
| Posted by: GreenBar0n on 2025-03-07 11:12:51 It took forever to get that din-8 to DB9 cable from ebay. When I connect it between a PC/USB COM port and the SE/30 serial port next to the audio output jack, I get no flashing cursor or keyboard input in Putty or TeraTerm, both set to 9600, 8, 2 stop bits, no parity, no flow control. Have a null modem adapter on the way tomorrow, to see if this is what the problem is and why I get no cursor. | |
| Posted by: adespoton on 2025-03-07 12:18:57 Not all DIN-8 to DB9 adapters are created equal; some contain the minimal pins and logic to print to a dot matrix printer and don't handle other hardware. Had this issue years back trying to get a hardware dongle to work. | |
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