AAPL,e411
AAPL,3400/2400
AAPL,cpu-id property.Anyone tried to place/remove 51ohm R207 on the SRS_PRSNT line to proof it?Those resistors are wired derectly to the OHare ASIC, see U5 (343S0172).
They form the so-called BoxID that can be obtained by reading OHare's CPU_ID register.
Disassembling of the logic board is not required.
The OHare CPU_ID register is located at 0xYY000034 where "YY" represents the base address of the chip assigned during machine startup.
Apple's HWInit sets OHare's base address to 0xF3000000.
Thus reading one byte at 0xF3000034 will return the BoxID set up by the above mentioned resistors.
Please keep in mind that Apple engineers used different names for well-known things causing confusions:
CPU_ID has nothing to do with the processor itself, CPU stands for logic board design in this case
BoxID usually means enclosure, for example, Gazelle or TAM
Here the disassembly of the startup bong playback routine from the Gazelle ROM:
Code:fn_FFF03D68: lisori r3, 0xF3000000 # load OHare's base address lisori r4, 0x34 # offset to the IDs register lwbrx r4, r4, r3 # read OHare's IDs register with endian swap rlwinm. r4, r4, 0,17,17 # isolate bit 6 of the Media Bay ID subregister bne l_FFF03D90 # branch if it's set lisori r3, 0xFFE00010 # load base address of the Gazelle bong b loc_303D98 l_FFF03D90: lisori r3, 0xFFE80010 # load base address of the TAM bong l_FFF03D98: lwz r4, 0(r3)
In other words, the startup bong playback routine looks at bit 6 of the Media Bay ID register.
This bit reflects the status of the DEV_ID2 pin that is connected to SRS_PRSNT signal.
SRS_PRSNT (active low) means surround sound is present if this signal is pulled low (see R207 pulldown in the Gazelle schematic).
If SRS_PRSNT is pulled low, the ROM will play the Gazelle startup bong.
Otherwise, you'll hear the TAM bong.
Anyone tried to place/remove 51ohm R207 on the SRS_PRSNT line to proof it?![]()
NiceHeck, why not?

Yeah gonna give that a try I just find it really weird because I've done the overclock before but for some reason it is disabling video. Maybe with higher clock speed and that resistor removed it is looking for a TAM style display or video driver and not one built into the machine?Interesting. Sound like this is a easy thing to test by repopulate R207?
Yeah gonna give that a try I just find it really weird because I've done the overclock before but for some reason it is disabling video. Maybe with higher clock speed and that resistor removed it is looking for a TAM style display or video driver and not one built into the machine?
0 > f3000034 rl@ 8 u.r 7A1030E0 okAnyone with a 5500/6500/TAM able to get the value returned by this command in Open Firmware?
Code:f3000034 rl@ 8 u.r
Which Mac model is that from?0 > f3000034 rl@ 8 u.r 7A1030E0 ok
I just plucked off R133 to drop the CPU from 300 to 275 and saw no change, I still see:Does overclocking or under clocking affect any of the bits of f3000034 ?
I just plucked off R133 to drop the CPU from 300 to 275 and saw no change, I still see:
0 > f3000034 rl@ 8 u.r 7A1030E0 ok
hid1@ 8 u.r
(fp_id << 24) | (mon_id << 16) | (mb_id << 8) | cpu_id | (this->emmo << 4)[/icode]
| DD2CSelect | Flat Panel ID | Monitor ID | Motherboard ID | CPU ID |
| | 7A | 10 | 30 | E0 |
| ? | F2 F1 F0 ? ? ? ? | ? M2 M1 M0 ? ? ? ? | 0 D2 D1 D0 ? ? ? ? | C3 C2 C1 C0 ? ? ? ? |
FP_ID2 = RP2 10K pull up = high
FP_ID1 = AMP_OE1 = RP2 10K pull up = high for pm6500.
FP_ID0 = MIC_SENSE = J13 Communications Slot = J6 microphone input = high unless microphone connected?
MON_ID2 = BPWM = 0 for pm6500 because it doesn't have a display.
MON_ID1 = CPWM = 0 for pm6500 because it doesn't have a display.
MON_ID0 = FAN_CNTL = R169 pull up
These are connected to J18 via U34
DEV_ID2 = RP1 10K pull up = SRS_PRSNT; R207 pull down exists for TAM but is missing in pm6500.
DEV_ID1 = RP1 10K pull up, SNOOP_EN; R8 down (is this resistor missing to make it high/not connected to ground?)
DEV_ID0 = RP1 10K pull up, SCC_ENAB = U15 and J13 Communication Slot = pulled high?
CPU_ID3 = CPUID3 = R224 4.7K up
CPU_ID2 = BOX_ID2 = R273 4.7K up
CPU_ID1 = BOX_ID1 = R272 4.7K up
CPU_ID0 = BOX_ID0 = R165 (is this resistor missing? or grounded by J18 ?)
Beige G3 connects a EMMO button to BOX_ID0. It is active low, so this bit is normally 1.
| ? ? ? ? |
| out oe2 oe1 oe0 |
oe2 = output enable for ID2
oe1 = output enable for ID1
oe0 = output enable for ID0
out = signal level for enabled output
cr " mac-io" find-device " assigned-addresses" active-package get-package-property device-end 2drop 8 + @ 34 + constant idreg
: probe-id ( idreg -- )
>r
0 r@ rb! 1 ms r@ rb@ 2 u.r
0 r@ rb! 1 ms 4 r@ rb! 1 ms r@ rb@ 2 u.r
0 r@ rb! 1 ms 2 r@ rb! 1 ms r@ rb@ 2 u.r
0 r@ rb! 1 ms 1 r@ rb! 1 ms r@ rb@ 2 u.r
0 r> rb!
cr
;
: probe-ids
idreg 4 dump
cr 4 0 do 3 i - idreg + probe-id loop
;
probe-ids
80800034: a0 20 10 70 :. .p:
70345261
10141211
20240221
a0a4 \ probing CPU_ID hangs on B&W G3 when trying to set BUS_SPEED[1] to 0
Copy and paste? You would have to do one line at a time, or increase the serial text pacing delay.Presuming I'm using a Power Mac 6500 via serial, how is this entered successfully?


dl is fastest - it probably doesn't require increasing the text pacing delay.dl command.