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Update on the update system redesign (haha): In the top left is the basic component placement for the new update system. It consists of the CH340G USB-serial chip, crystal (different, cheaper package than before), and just a single $0.15 74AHCT573 tristate buffer (really a latch but that...

Yep, alxlab has it exactly right. You need the SWIM floppy chip (as opposed to IWM) on your SE motherboard in order to use 1.44 MB disks. Regarding the choice of CPU, MC68HC000 doesn't really offer any more features than MC68000, just lower power and more speed. There's also MC68SEC000 which is...

Maybe but I find that the problems get fixed and then it’s kinda cumbersome to maintain the spreadsheet. Spreadsheet is better in the release candidate stage when the gizmo is almost done in order to find if there are any “compatibility caveats” that need listed in the manual. I’ll test more on...

Yes, I think we will start out at $125 for the first 100 or so units, then the price may have to increase to $150 for the subsequent units because of parts sourcing issues and additional cost related to design changes I need to make for the second revision. The current design is made from...

Hmmm yeah that’s right, it failed on the 3rd pass. Can you reproduce it? Sometimes this can happen from a dirty contact or from jiggling the cards too much.

Uh ohhh, hope you can get it sorted. Anyway 16 MB mode is kinda finicky; I think it works fine in hardware but almost every app I’ve tried doesn’t play nice with 16 MB. If GS/OS doesn’t detect the card as a disk device with it set to 16 MB but 8 MB works then I oughta switch the 16 MB mode to...

Yeah, good choice too although they draw a bit of static current as opposed to the 'LVC125s which only really draw current when they switch. It's just a few mA though, no big deal. Hmm maybe you can't parallel LVT-series though, being that they're BiCMOS (bipolar+CMOS). I am not sure. But I...

Small update on the project. Long story short, we are prototyping the USB update system for this accelerator on an upcoming Commodore 64 RAM product. Cost is a bit tighter on that card than this accelerator so we have eliminated the update microcontroller on there and we will be directly...

Ah! Okay no big deal. You can parallel multiple CMOS outputs (at the expensive of potentially violating the maximum capacitance spec) to get more drive strength. So you can hook up three or four buffers together to get the right drive strength. In general this only works with CMOS though, not...

Okay I’ll bite. PM me your address and I’ll send you one. Okay sorry for not getting back to you guys earlier. The first order of business is just to run the self test. Steps are pretty straightforward: Install the card into any free peripheral slot (so not the aux or memory expansion slots)...

Oh, I wouldn’t look at the schematic for this as a good reference on how to design a NuBus card. It’s a work in progress and I have not actually fabricated a board yet. Anyway about the drive strength required to drive the NuNus, it’s actually not as bad as you’re saying. You only need 24 mA DC...

I've been doing test vectors and everything is looking good. Here's one picture which is admittedly incredibly hard to read--probably nobody should bother with it: Anyway, the point is that the above picture is showing a simulation of the DRAM controller behavior under some reasonable...

Yes, please! Then we can verify cy384's xor checksum theory. Nah, you can only “restart in MS-DOS mode” on Win9x. I use a ThinkPad T22 for this kind of purpose. Runs DOS, Win9x, and XP well enough. By the way, regarding the XOR checksum byte, I looked at SonicEnet.a and yeah, it does appear...

Yeah, try installing on Win95 and then “restart in MS-DOS mode.” Or just copy the CD files to disk and then install from your hard drive. If none of that works then it’s pretty easy to get the CD-ROM drivers working in DOS. Try this link: http://manmrk.net/tutorials/DOS/cdrom.htm

Yes yes! That oughta be it. And the preceding 55 and AA bytes before the checksum byte are just to check for shorts between adjacent pins on the data bus. The bit ordering thing is odd though. I believe my MAC is backwards too (have to recheck) but I’m not sure. We’ve just gotta see a few more...

Ooh, thanks! Still expensive from the big suppliers ($12, MOQ 200) but much better than I was seeing before for the KEL part. Hopefully I can identify a smaller supplier with a big stock of the 3M connectors available for cheaper and smaller quantity.

Anyone have a source for the PDS connector used on a Quadra 700, 900, 650, and 800 PDS slot card? According to the Quadra 700 dev note, the connector you put on a PDS card is a KEL 8807-140-170LH. Can’t find that anywhere for a reasonable price. I see some discussion on 68kMLA where one...

Yes, it would be a great help if you could post the ROM contents (using MacsBug as I described in the first post) and also the MAC addresses of your machines. The 660AV ROM dump will help me figure out what the 10 bytes after the MAC are on my 660AC. Then the 650 ROM will help to see whether the...

Hi again, sorry for not getting back to you guys earlier. I think we have to limit testing to people with at least two of the three supported machines--][, //e, and IIgs to make sure we're getting good test coverage on all the supported machines. So @eric and @Patrick I'll message you guys to...

Here's my latest design for a Mac IIfx RAM SIMM. As always, it's a collaboration with Garrett Fellers and open-source even for commercial use if you remove the Garrett's Workshop trademark. Now, unfortunately I don’t have a IIfx so I will need some help testing these once I get em. My rule is...