Recent content by joevt

I wish I had bothered to look at the Figure 5.2 that Figure 8.5 was pointing to when I was looking at Figure 8.5 the first time.

I believe it's an actual Apple Open Firmware implementation that uses some info from System 7.5 (search for >hwinit). I don't know how it compares to the stub you mention. It's more than just a device tree. It has Open Firmware packages and drivers. It has version 2.0 so it's newer than the...

Apple did make a Open Firmware for NuBus Power Macs. It's part of the Copland boot process. It is loaded by System 7.5 and uses some info from System 7.5 (video framebuffer information, Open Firmware section of nvram from a binary file, etc.). It is being discussed on the DingusPPC discord. I...

Congrats on solving the problem! The LS166 did appear to be shifting bits correctly - all characters being displayed had all bits matching the bits of a character from the Video ROM (Figure 8.8 #5 ) which means bytes from the Video ROM were being received by the LS166 correctly. The...

Open Firmware does contain code for MFM drives. Open Firmware, 2.0.2 for PM 4400 and 7220 can choose between a MFMfloppy device and a swim3 device depending on some value read from a board register at offset 1a000 of OHare. There's a Open Firmware driver for swim3 but not MFMfloppy. In Open...

I don't know anything about that. The PCBs from DIYINHK are not mentioned in the air cooling links I posted. They are mentioned here: Past summer project - G5 Quad LCS rebuild LCS Issues Late 2005 Quad

I have no info regarding G5 air cooler compatibility with G5 liquid cooled CPUs. I linked some air cooling threads at #9

These are the recent ones: https://forums.macrumors.com/threads/because-i-can-air-modding-a-quad-with-pc-coolers.2427612/ https://forums.macrumors.com/threads/air-cooling-a-late-2005-g5-quad.2455900/...

There's a couple Quad G5 air cooling threads on MacRumors. They use third party air coolers - 92 mm.

MacRumors has a couple recent threads on converting a Quad G5 to air cooling.

The point of setting all the bytes in the text to all the same value is so that you can find that byte value on the bus. You're saying the VIDEO ROM is getting all the bits of the value correctly? That doesn't seem possible. Did you compare VID6 to the IOU with A9 to the VIDEO ROM? Do they match...

Here's another test program. Change the value in line 5 to any bit pattern or character you think might be helpful. 5 TEST = 255-64 10 FOR Y = 0 TO 23 20 AB = INT(Y / 8) 30 CDE = Y - AB * 8 40 OFFSET = CDE * 128 + AB * 40 50 FOR X = 0 to 39 : POKE 1024+OFFSET+X,TEST : NEXT 60 NEXT 70 POKE...

I think so. Do you mean the IOU at E5? I guess if you're done looking at all the traces to the Video ROM at F4 then sure, try the IOU chip. You said all the traces had variable signals. Did you check the voltage levels to make sure that low is low enough and high is high enough?

This is a better test: 10 HTAB 1:VTAB 1: PRINT " `Aa": PRINT PEEK(1024) " " PEEK(1025) " " PEEK(1026) " " PEEK(1027) I tested it at https://www.scullinsteel.com/apple//e The result is 160 224 193 225 which are 0xA0 0xE0 0xC1 0xE1 The problem you're trying to track down is why character 0xA0...

You can try AppleSoft Basic using the PEEK command. Something like this: 10 HTAB 1: VTAB 1:PRINT " ": PRINT PEEK(1024) 20 HTAB 1: VTAB 1:PRINT "A": PRINT PEEK(1024) https://www.calormen.com/jsbasic/reference.html