| Click here to select a new forum. |
| What is the SWIM PIC? |
Posted by: olePigeon on 2022-08-21 18:51:46
I was extracting chips off my battery bombed IIfx, and right next to the SWIM chip is the SWIM PIC. Any idea what it's for? |
Posted by: Unknown_K on 2022-08-21 20:35:48
The IIfx had a special serial controller chip to offload work from the 030 (only mac II to have it), could that be it? |
Posted by: olePigeon on 2022-08-22 09:29:04
I'll keep it bundled with my SWIM chip, then. I guess I was curious what was on it, and how it related to the SWIM chip. Like if the IIfx had an extra floppy shenanigans going on. |
Posted by: olePigeon on 2022-08-22 09:36:01
Also, my new cheapy-deapy hot air machine works fine. I broke it out yesterday to extract all the chips and a few of the black IIfx capacitors. I got the cheaper model after I returned the fancy (but still relatively cheap) model that didn't seem to ever get hot enough despite the temperature set to max and the airflow to low. I think it was broken. |
Posted by: Unknown_K on 2022-08-22 10:22:16
What models were they (hot air stations)? |
Posted by: olePigeon on 2022-08-22 10:49:33
I'll have to look when I get home. Just one of the generic Chinese models sold under 100 different names on Amazon and eBay. |
Posted by: Gorgonops on 2022-08-22 11:10:26
The "PIC" is more commonly known in the Apple docs as the "IOP"; the IIfx (and Quadra 900/950) have two of them programmed with different firmware; one sits in front of the serial ports and the other in front of the SWIM and the ADB ports. It's a custom MCU based on a 6502 core with a piddling amount of built-in RAM and a shared memory interface to the 68030, and it's intended to allow the main CPU to offload some of the hairier (and very timing-sensitive) aspects of handling disk I/O off so it can do other things.
Under plain MacOS these chips didn't accomplish much and were effectively kind of pointless, but the idea was sound and I vaguely recall reading that A/UX got at least some use out of them. |
Posted by: olePigeon on 2022-08-23 08:37:13
@Gorgonops So about as useful as A/ROSE. 😀 |
Posted by: MOS8_030 on 2022-08-23 14:51:48
@Gorgonops So about as useful as A/ROSE. 😀 That made me laugh!
From Wikipedia:
"A/ROSE is infamous for its esoteric purpose, which is generally not understood by Mac end users, as well as for causing many Mac emulators, such as Basilisk II, to produce a system error at boot time."
I think in all the years I've used Macs I only ran across one that actually needed the A/ROSE extension (network card) yet I saw it on hundreds of Macs because for years it was installed by default. |
Posted by: NJRoadfan on 2022-08-23 14:55:31
At least some of the design work saw practical use. Although it was built from discrete components, The Apple II 3.5" Controller Card uses a 65c02, a bit of RAM, and a SWIM to run floppy drives. The IOP is too system specific to use on an Apple II card though. |
Posted by: Gorgonops on 2022-08-25 15:45:48
The Lisa actually used a similar system to drive the floppy drives. Again, there's nothing really "wrong" with it in theory, it's a pretty big win in a multitasking system to not have to stall the main CPU so it can literally count cycles bit-banging disk I/O. It just didn't really pay off that much with the Mac System OS because it was by design not great at taking advantage of that sort of help. |
| 1 |