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| Macintosh II 030 Adapter c´t 7/93 ... |
Posted by: franklyn on 2026-09-06 23:06:17
... made a PCB and customize it to the Macintosh II
Not sure I can make the GAL work ...?
It is intended to be a rough draft and may need to be adapted for the Macintosh.
cache = /fc1 * /a23 * /a22 ;$0-$3FFFFF RAM
+ /fc1 * /a23 * a22 * /a21 * /a20 ;$400000-$4FFFFF ROM
+ /fc0 * /a23 * /a22
+ /fc0 * /a23 * a22 * /a21 * /a20
I’ve already put a ROM upgrade to the FDHD kit version in.
Shouldn't an 030 CPU be supported directly, without needing that control GAL on the adapter?
The problem is, I have absolutely no idea about this and need help... |
Posted by: Trianon on 2026-09-07 05:07:47
Hi,
I can compile PAL code and program them, but you say you need an GAL ? What type is it, speed grade will be very important.
Maybe a stupid question, what speed increase do you expect from this ? You are using the same clock and same slow memory (68030 has faster burst mode). Only difference will be larger cache but without the faster ram interface filling the cash could be an issue, even making it incompatible for SW. |
Posted by: franklyn on 2026-09-07 05:14:20
I can program GALs too, so no problem. The 030 CPU run at system speed from 16Mhz. I was thinking the SE030 ROM (FDHD ROM Update) can handle the 030 CPU ...
There was a little fault in the layout and I order 5 pcb´s now ... |
Posted by: Bolle on 2026-09-07 07:10:34
You should get away with just pulling /CIIN high. There shouldn't be a need for the GAL in a Mac II. |
Posted by: Melkhior on 2026-09-07 07:16:11
Maybe a stupid question, what speed increase do you expect from this ? You are using the same clock and same slow memory (68030 has faster burst mode). The II's memory controller answer with /DSACK[1:0] so burst mode won't be used - it needs /STERM and st handling. No benefits without a ROM update. The MC68020 doesn't have a data cache when the MC68030 does, so using a ROM that enable the cache should help a bit. |
Posted by: franklyn on 2026-09-07 07:50:15
You should get away with just pulling /CIIN high. There shouldn't be a need for the GAL in a Mac II. ... so I desolder the 4,7k Pullup on the CIIN and put not a GAL in the Adapter. |
Posted by: zigzagjoe on 2026-09-07 08:33:11
... so I desolder the 4,7k Pullup on the CIIN and put not a GAL in the Adapter. No, you want the pull-up still.
The GAL is intended for the case where you've dropped the 030 in place of an 020 and the system firmware doesn't know what an 030 is. If you were to enable the 030 data cache under those conditions it will cache inappropriate data such as data from IO devices. That's going to break things. The GAL would decode accesses and pull on the CIIN (Cache Inhibit) line appropriately to prevent those accesses from getting cache.
The Mac II FDHD ROM *does* know what an 030 is - it's also used by IIx, IIcx, SE/30 - so it will configure the '030 MMU to cache-inhibit the appropriate regions before enabling the data cache. So, the CIIN line just needs to be left pulled high (deasserted) so the data cache can function.
I'd be interested in the board files for this when done; I've been too lazy to do it myself in order to confirm that of my Booster 2.0s would work in a Mac II @ 47mhz. |
Posted by: franklyn on 2026-09-18 12:57:47
Works very well with the SE/30 ROM update...
... the next step is installing or swapping in the SWIM floppy controller to enable HD floppy support. I'll start with a "flying lead" setup and then design a PCB for it later... |
Posted by: franklyn on 2026-09-18 22:58:36
Mode32 ... |
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