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LC with No SCSI Drives Recognised
Posted by: Phipli on 2023-07-03 05:23:04 Afternoon folks. My dad dropped over an original (020) LC last week and I've been bringing it up. Its in reasonable condition, corrosion wasn't too bad. I've recaped it, I'm using a known good PSU, and has been cleaned in an ultrasonic. So far, the PSU was dead, then it wouldn't chime until I recapped it. Now its slightly hesitant to show the question mark, and if I boot it from a floppy disk, it doesn't see anything on the SCSI bus. Internal or external. The Egret was a bit grotty, but not so bad that I'd assume it was damaged. Interestingly where SCSI Probe tells you whether the bus is terminated or not, that is working. So SCSI Probe tells me that the bus is not terminated if I have absolutely nothing connected to SCSI. Any common issues likely to cause SCSI detection issues, before I get stuck in? Please remember that I'm limited to a floppy drive and I'm not really a... floppy drive user so I'm going to struggle to run much software on this. To hand I have System 6.0.7, HD SC Setup, Drive Setup (a 7.5.3 disk that boots straight into drive setup), SCSI Probe and not much else.
Posted by: Phipli on 2023-07-03 08:26:23 Tum te tum... Ask no question, hear no lie.
Posted by: Skate323k137 on 2023-07-03 08:29:54 Broken trace to the SCSI IC?
Posted by: Phipli on 2023-07-03 08:34:08 Broken trace to the SCSI IC? There is a trace, erm... SEL on pin 57. It goes under the chip but doesn't have continuity to where it should go. A temporary bodge to see if this is my issue gives this :
Posted by: Phipli on 2023-07-03 08:59:50 Hum. It really doesn't like not having a disk on the internal bus. More so than my other macs.
Posted by: Skate323k137 on 2023-07-03 09:30:45 Is it a situation like an SE where both ends of the bus need terminated? Good job so far.
Posted by: Phipli on 2023-07-03 09:42:03 Is it a situation like an SE where both ends of the bus need terminated? Good job so far. Technically you should always terminate the internal bus if you don't have a disk on it, but this is the first time I've had issues with it. SCSI weirdness. The rules aren't rules, you don't always have to follow them, but once in a while, not following a rule bites you in the bum. Seems to be happy now. I'll tidy up the bodge and call it a day. Passed a hardware test and ran a benchmark (slowly).
Posted by: Phipli on 2023-07-03 09:54:24 Benchmark scores. It falls between the SE and SE/30, video is identical to a Toby in a Mac II. Disk is crazy fast because I have a 2000s server disk connected, FPU is abysmal because I don't have one. Not much difference between the LC and the LC II really. Unsurprisingly.
Posted by: Skate323k137 on 2023-07-03 11:01:11 The rules aren't rules, you don't always have to follow them, but once in a while, not following a rule bites you in the bum. Big facts. I'll tidy up the bodge and call it a day. I think I'd do the same 🙂 I always play it safe with SCSI. Even simple stuff like using the extra power connector on SCSI SD devices even if they can get by on termination power.
Posted by: Phipli on 2023-07-03 12:02:47 And done... slightly scruffy, but will do. Machine seems to be happy now. Its decades since I've used an original LC. It is as slow as I remember 😆
Posted by: joshc on 2023-07-03 12:19:40 Nice fix. They are fine for simple things. Try it with System 6 and WriteNow. SuperPaint should work ok as well. Basically anything that worked well on the SE, but in colour!
Posted by: Phipli on 2023-07-03 12:25:33 Nice fix. They are fine for simple things. Try it with System 6 and WriteNow. SuperPaint should work ok as well. Basically anything that worked well on the SE, but in colour! Yeah, I'm seeing it as a slightly speed bumped SE, like a brainstorm or something 🙂 Need to do something with the PSU. I have three LC cased machines and only one functional PSU. Perhaps a project for this month.
Posted by: Snial on 2023-07-03 13:45:18 The LC is going to be nearly as slow as my LCII, surely? The only difference is that the 68030 has 256b of instruction cache + 256b of data cache vs 256b of instruction cache (or unified cache). What OS were you testing it on? Oh yes, and that's shown in the tests, because the LCII scores 19.1 vs 17.9 for the CPU. A 7% improvement! Given that it's 22.6 for the Mac II (also a 68020), implies it's a 26% performance boost for a 32-bit bus (so a 16-bit bus is fairly decent, much better than half the performance), but that's reduced to 18% because of the CPU.
Posted by: Phipli on 2023-07-03 13:49:19 The LC is going to be nearly as slow as my LCII, surely? The only difference is that the 68030 has 256b of instruction cache + 256b of data cache vs 256b of instruction cache (or unified cache). What OS were you testing it on? Oh yes, and that's shown in the tests, because the LCII scores 19.1 vs 17.9 for the CPU. A 7% improvement! Given that it's 22.6 for the Mac II (also a 68020), implies it's a 26% performance boost for a 32-bit bus (so a 16-bit bus is fairly decent, much better than half the performance), but that's reduced to 18% because of the CPU. I found it interesting that the video score matched the Mac II, given the Mac II should calculate QuickDraw faster. Not sure how. Yeah, the LC II is a small amount faster 🙂 guess the LC would have matched the IIs CPU score with a 32bit bus.
Posted by: Snial on 2023-07-04 10:59:46 I found it interesting that the video score matched the Mac II, given the Mac II should calculate QuickDraw faster. Not sure how. NuBus was only 10MHz I think initially? Yeah, the LC II is a small amount faster 🙂 guess the LC would have matched the IIs CPU score with a 32bit bus. Yep!
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