Power Macintosh PPC ROM DIMMs

stynx · Oct 12, 2024

Incomplete List of ROM modules:

type-number	voltage	computer model	chips	special features	reprogrammable
820-0961-A	3.3V	?	4x AM29LV800	unpopulated sop & plcc	yes?
820-0954-01	3.3V	PM G3	2x KM2316205Y	2x 70 pin chips	no
341-0758	5V	PM 9500	8x HM27C4000FP-12		no, OTP?
341-0757	5V	PM 6/7/8100			no
341-0741	5V	PM 6/7/8100			no
341-0833	5V	ANS 500/700			no
820-0672-A		PF63x0		ROM & Cache	no
333-1087		PF62x0		ROM & Cache	no
"Apple ESB ROM"		ANS
"PEX proto ROM"	5V?	Power Express 9700	16x AM28F020	prototype related	yes

ToDo:

Find more ROMs
find and add "Gazelle Flasher" utility
add old Flash-util from an early TNT PCI DDK (MacOS 7.5.2 PCI_DDK_vA5)

Goals:

get the flashing of old World PPC Mac Rom modules working.
find a way to create flash ROM modules
complete the list of the available ROM modules

John Tucker · Oct 14, 2025

Greetings,

It has been a year since this was posted. I was curious if progress has been made with either the Todo or goals.
I have three DIMMs that appear to be the same as IMG_6823.jpg. I have a strong desire to duplicate/copy the contents
of one of the ROMs to one of the others. It would be great to have the ability to create additional copies if writeable
ROM DIMMs can be had. I had hoped that the ROM programmer I have from CayMac would accomplish this but the
ROMs are different.

Any info would be appreciated.

Thanks.

Jockelill · Oct 15, 2025

Me and @dougg3 discussed this topic like 2 years ago (time flies)

, the idea was to make an adapter for the ROM SIMM Programmer that also could do the PPC ROMs, but at that time the biggest issue was us sourcing the necessary female slot connector (PPC ROM SIMM connector) for the adapter (yeah, stealing one from an old board could work, but wouldn't be very viable). Then life and other projects has kept us away from the concept

.

The other solution would be to just use sockets reflashable chips of appropriate size and flash wil like an X-48.

Software wise I remembered that @dougg had an idea for a solution.

The pin out of the PPC ROMs (Power Surge, G3 is totally differnet and 3.3V) is at least:

Pin		PS
1		Vcc
2		GND
3		Vpp? (this would be used on a programmable module with old EEPROMs)
4		D0 HL
5		D1 HL
6		D2 HL
7		D3 HL
8		N/A
9		Vcc
10		NC
11		D4 HL
12		D5 HL
13		D6 HL
14		D7 HL
15		GND
16		D8 HL
17		D9 HL
18		D10 HL
19		D11 HL
20		NC
21		Vcc
22		NC
23		D12 HL
24		D13 HL
25		D14 HL
26		D15 HL
27		GND
28		NC
29		NC
30		A2
31		A4
32		A6
33		A8
34		A10
35		NC
36		NC
37		WE (For programmable modules, also may connect to pin 117)
38		OE A1L (May also connect to pin 118)
39		NC
40		NC
41		Vcc
42		NC
43		GND
44		A12
45		A14
46		A16
47		A18
48		NC
49		NC
50		NC
51		NC
52		NC
53		GND
54		D0 HH
55		D1 HH
56		D2 HH
57		D3 HH
58		GND
59		Vcc
60		NC
61		D4 HH
62		D5 HH
63		D6 HH
64		D7 HH
65		GND
66		D8 HH
67		D9 HH
68		D10 HH
69		D11 HH
70		NC
71		Vcc
72		NC
73		D12 HH
74		D13 HH
75		D14 HH
76		D15 HH
77		GND
78		NC
79		NC
80		Vcc
81		Vcc
82		GND
83		NC (May be Vpp on programmable modules)
84		D0 LL
85		D1 LL
86		D2 LL
87		D3 LL
88		NC
89		Vcc
90		NC
91		D4 LL
92		D5 LL
93		D6 LL
94		D7 LL
95		GND
96		D8 LL
97		D9 LL
98		D10 LL
99		D11 LL
100		NC
101		Vcc
102		NC
103		D12 LL
104		D13 LL
105		D14 LL
106		D15 LL
107		GND
108		A0
109		A1
110		NC
111		A3
112		A5
113		A7
114		A9
115		_CE
116		1Kohm to GND?
117		WE for back of module on programmable modules, may also connect to 37
118		_OE all, also connects to 38
119		NC
120		NC
121		Vcc
122		NC
123		GND
124		A11
125		A13
126		A15
127		A17
128		NC
129		NC
130		NC
131		NC
132		NC
133		GND
134		D0 LH
135		D1 LH
136		D2 LH
137		D3 LH
138		NC
139		Vcc
140		NC
141		D4 LH
142		D5 LH
143		D6 LH
144		D7 LH
145		GND
146		D8 LH
147		D9 LH
148		D10 LH
149		D11 LH
150		NC
151		Vcc
152		NC
153		D12 LH
154		D13 LH
155		D14 LH
156		D15 LH
157		GND
158		NC
159		NC
160		Vcc

Performa450 · Oct 15, 2025

Here’s another one - AP2216-03 from the Power Mac 4400 prototype. It has 16x AM28F020s

Jockelill · Oct 15, 2025

Interesting that they used AM28F020 for those, it's also the same they used for the LOBOS board:

https://68kmla.org/bb/index.php?threads/lobos-board-strange-apple-rom.39963/

And the STB3 (although in a different form factor):

Apple's Interactive Television Box: hacking the Set Top Box System 7.1 in ROM

This article has been revised with recollections and corrections from former Apple employee Al Kossow, some good folks on Hacker News and t...

oldvcr.blogspot.com

Jockelill · Oct 15, 2025

Pretty sure they had a LC PDS programmer with a DIMM socket and then flashed them using the Flasher tool on a Q605 machine. @dougg3 built an LC programmer (and later I made a proper board for it):

Downtown Doug Brown » More fun with Apple’s internal tools: creating a PDS card

www.downtowndougbrown.com

But are pretty sure the same tool can also reflash PPC ROMs, so that could also be an option. I can reflash both the Red Rom from an STB and LOBOS board inside my LC475 using these tools.

Power Macintosh PPC ROM DIMMs

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