Recent content by David Cook

Those are all off the shelf parts. The numbers like 8914 are dates. That's the 14th week of 1989. The part numbers are: UA8: 74F253 UB8: 74F253 UC8: 74F253 UD8: 74F253 UE8: 74LS166 UF8: 74LS393 UG8: 74LS393 Check out the last page of the schematic attached.

I was fortunate to pick up an uncommon upgrade for the pizza-box Macs: A DGR Max Expansion. This is similar to the MicroMac Power Workstation and the MicroQue LC Top Hat. It consists of a metal chassis that fits between the top and bottom of a stock LC case. The rear includes a second power...

1 to 1: GND to GND 2 unused: +5V 3 to 3: GND to GND 4 to 8: transmit+ to receive+ 5 to 9: transmit- to receive- 6 unused: +12V 7 to 7: external clock to external clock 8 to 4: receive+ to transmit+ 9 to 5: receive- to transmit- A RS-422 crossover cable with external clock pin

I assume the same message even with the serial port disconnected? I mean, I suspect this message is really saying "I can't talk to the Tecmar at all".

Check the continuity on all of the serial cable pins. The MacGUI article indicates the drive clocks the serial port externally. Use a serial breakout board to verify communication. MacGUI said they had to leave the drive on for an hour for it to warm up and be recognized. Try disconnecting...

Yes. No problem. As commonly occurs, whenever the PRAM battery has died or is removed, the date goes to 1904. That's exactly what will happen when the clock rolls over in 2040. The Mac works just fine. Yes. A number of people have put considerable thought into the subject. 1. Improving the...

Way back in 2008, @JDW pointed out the following article in which an unnamed init could enable a stock-ROM SE/30 to mount an HD20 hard drive (or Floppy EMU emulating an HD20). https://web.archive.org/web/20030303085358/https://docs.info.apple.com/article.html?artnum=6182 "Additionally, we have...

One of my favorite things about this hobby is upgrading these old machines to their maximum potential. It's like fulfilling a promise.

That is an amazingly crisp image.

Check for capacitor damage around C2. There are a lot of traces related to the CLUTDAC (UJ10) that run nearby. See sheet 5 of 5 on the schematic.

I agree that the new order makes a lot more sense, particularly since events can be added during interrupts. So, an event can be posted as the other managers are initialized. In the 1983 (pre-launch) technical notes, they say: "Before using the Event Manager, you should call the Window Manager...

You are very kind. This only runs on "classic" B&W Macs because Andy is not calling Bill's Quickdraw routines (FillRect and CopyBits) -- which is ironic given the thread it is posted to. : ) It also won't likely run with MultiFinder active, which is also somewhat ironic given Andy's later work...

Extracted and converted to BinHex (aka Tiny Transfer) format

Bill Atkinson was one of my heroes. As a young software engineer, I spent many commutes and sleepless nights trying to figure out how regions worked. The best I could come up with was a tree of rectangles with an in/out/check-child-nodes flag to determine if a pixel should be drawn or not. A...

Updated Tiny Transfer attached. Fixed “Missing or incomplete footer” errors when the footer happens to fall on a boundary such this it is processed in parts rather than all at once. When sending via XModem, very compressible files can cause a delay before sending the next packet, because the...