68kMLA Classic Interface
This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.
| Click here to select a new forum. | |
| SE/30 VIA chip replacement | |
| Posted by: croissantking on 2023-06-16 08:48:16 Is any 65C22 PLCC44 chip usable as a replacement for the SE/30 VIAs, such as this one?… 
Western Design Centre W65C22S6TPLG-14 (CMD / Rockwell) VIA | eBayFind many great new & used options and get the best deals for Western Design Centre W65C22S6TPLG-14 (CMD / Rockwell) VIA at the best online prices at eBay! Free delivery for many products.
www.ebay.co.uk
| |
| Posted by: mari3311 on 2023-06-17 23:09:23 VIA of SE/30 is 338S6523 (11484 -28, -30, -44 etc. ) = R65NC22J (Rockwell) VL65C22V-02QC (VLSI) Model numbers are from multiple SE/30's on real machines. I think the closest thing to R65NC22J is W65C22N6TPLG-14, not W65C22S6TPLG-14. Please refer to P.32-35 and P.50 of the PDF. A long time ago, I bought one listed as "R65NC22J4 (11484-39)" on Taobao and it worked fine. | |
| Posted by: croissantking on 2023-06-18 03:41:32 I will try the W65C22N6TPLG, it’s available on Mouser. From the PDF you linked, it appears there are some minor design deviances regarding the port buffers. I don’t think TaoBao is accessible to foreigners anymore, pity as some sellers currently have the R65NC22J4. | |
Posted by: MegaImg on 2023-07-03 21:42:54I will try the W65C22N6TPLG, it’s available on Mouser.Did it work? | |
| Posted by: croissantking on 2023-07-04 02:21:17 I’ve got the chip now, will test it soon and report back | |
| Posted by: Phipli on 2023-07-04 03:11:56 Hum. Just to warn you, the WDC part is not 100% compatible with older types. I forget the specifics, and the Mac might not use those features, but I know it isn't identical. | |
| Posted by: Phipli on 2023-07-04 03:14:22 There is an 'N' and an 'S' version. You bought the one that is designed to replace NMOS parts, which is probably the right thing to do, hopefully it is happy replacing CMOS parts too. | |
| Posted by: croissantking on 2023-07-06 16:42:37 So it does work. I mean, it boots up and I can use the computer. Do I need to do any specific kind of tests? | |
| Posted by: MegaImg on 2023-07-06 17:13:53 Floppy So it does work.How floppy, Mouse and keybord fuctions. Working ok? Both Connectors? | |
Posted by: Phipli on 2023-07-07 01:46:19So it does work.The first download here is for 68k : MacTest Pro - Macintosh GardenMacTest Pro is repair-oriented diagnostic software that can test logic boards, video cards, monitors, floppy drives, hard drives, and CD ROM drives. It can also detect software corruption problems, and the existence of multiple System Folders on a volume. MacTest Pro is intended for use by Apple...
it will test logic board chips, but you have to specifically turn the VIA tests on from the setup button. | |
| Posted by: MegaImg on 2023-07-09 06:39:12 Any updates! | |
| Posted by: croissantking on 2023-07-09 14:06:44 Not yet, but will test next week | |
| Posted by: croissantking on 2023-07-10 19:51:16 I’ve done a bit of testing. MacTest Pro is happy with the VIAs, and both sets of ADB and serial ports work fine. The internal floppy works too but I haven’t tried an external yet. No weirdness at all during about 2-3 hours’ use. Also just to mention that I tried the new VIA in both locations as my board is socketed. | |
Posted by: Phipli on 2023-07-11 01:57:51I’ve done a bit of testing. MacTest Pro is happy with the VIAs, and both sets of ADB and serial ports work fine. The internal floppy works too but I haven’t tried an external yet. No weirdness at all during about 2-3 hours’ use. Also just to mention that I tried the new VIA in both locations as my board is socketed.This all really confuses me. While the silkscreen says 6522, Apple's documentation says the SE/30 uses a 6523, at least for one of the vias. The 6523 is a different thing, it has 3 ports instead of 2 and other differences... The one you replaced must be a 6522, so it must have one of each. I need to sit down with some manuals and work out whats going on. Which VIA did you replace? VIA1 or VIA2? Do you have photos / what are the silkscreen labels? Sorry for asking, you've got me curious!  5th column is the SE/30 so... erm... eh? | |
| Posted by: Phipli on 2023-07-11 02:08:48 OK, so I found the following. It seems what Apple call the 6523 isn't the same part I found elsewhere. Its some kind of custom 6522 part that they've made with a synchronised serial port (I2C if I remember) and some bug fixes (the 6522 was famous for having a couple of bugs that the whole industry had to work around). If I remember, the WDC chip also fixes the main bug, but I'll have to remind myself of the specifics. That just leaves the behaviour of the I2C... My question would be... does the clock work properly? Can you set the time (insofar as you normally can). @Bolle do you know anything about the 6522 vs Apple's 6523 from your SE/30 projects?  | |
| Posted by: Phipli on 2023-07-11 02:13:22 Wikipedia has a section on the bugs, the WDC chip likely fixes them and so actually might be a really close match to Apple's 6523. 
MOS Technology 6522 - Wikipedia | |
Posted by: croissantking on 2023-07-11 03:50:58 | |
Posted by: croissantking on 2023-07-11 04:39:14does the clock work properly? Can you set the time (insofar as you normally can).It does. | |
Posted by: Phipli on 2023-07-11 04:41:06It does.Excellent sounds like we're good. I wish I had the internal apple spec for the 6523 🙂 | |
| Posted by: Phipli on 2023-07-11 05:07:55 Some light reading for anybody interested... The 6523 is the standard part fitted to the SE/30, the "VIA Cell" document describes the functionally similar cell that was baked in to other chips when Apple integrated the VIA in later machines. This document helpfully details where the new embedded cell differs from the previous 6523. Sadly I can't find a copy of Apple's spec 338s6503, which describes the 6523, but apparently the VIA Cell document is based on it. | |
| 1 > |