How much of the 128K/512K hardware has been reverse engineered?
- Thread starter Trash80toG4
- Start date
HUGE Apology so while this chip works (kinda) I've found one issue, the days jump randomly so instead of 1, 2, 3 it's like 1, 23, 5
Here's where my prep work stands:
Light Gray - off the shelf parts
Yellow IC - on Plus replaces SIP resistor pack on 128K board - Resistor Network?
Purple ICs - on Plus, but not on 128K
Purple IC Outlines - 128K ID in black - Plus ID in Purple = which Plus versions are usable?
Dark Gray ICs - No Clue
Connectors and Fence from Plus Donor
Board outline has SE/30 bezel/chassis compatible indent
Haven't looked at schematics yet, guessing the coils are amplifiers for sound output? They followed the jack in the Plus.
Plus has 4 yellow filter ICs - additional one is for SCSI controller?
Dunno, brain's fried. Comments?
Light Gray - off the shelf parts
Yellow IC - on Plus replaces SIP resistor pack on 128K board - Resistor Network?
Purple ICs - on Plus, but not on 128K
Purple IC Outlines - 128K ID in black - Plus ID in Purple = which Plus versions are usable?
Dark Gray ICs - No Clue
Connectors and Fence from Plus Donor
Board outline has SE/30 bezel/chassis compatible indent
Haven't looked at schematics yet, guessing the coils are amplifiers for sound output? They followed the jack in the Plus.
Plus has 4 yellow filter ICs - additional one is for SCSI controller?
Dunno, brain's fried. Comments?
HEH! Comparison here works, already spotted some stuff! Is that resistor pack bodge on VIA OEM or 512K upgrade
Plus - Top
Redux - Middle
128K -Bottom (w/512K Mod)
Missed ASG - Same on both boards?
Which Apple Chips are interchangeable?
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128k has a fat Mac mod hence the wires going everywhere. The Plus and 512k are stock (oddly enough never seen a ceramic 68k CPU on a 512k).
Yep, as noted. Was wondering about the resistor pack bodge? Factory rework of design flaw in early run boards, factory fix of faulty board or related to the wire spider infestation?
Thinking one 72pin SIMM instead of DIP DRAM. Itty bitty bits of it used for 128K. Lots of room on board for a flip of a gate switch bodge to access 512K? 128K and 512K playtime enabled in the 128K/512K Rechambered into Plus Case fork of this thread?
Thinking one 72pin SIMM instead of DIP DRAM. Itty bitty bits of it used for 128K. Lots of room on board for a flip of a gate switch bodge to access 512K? 128K and 512K playtime enabled in the 128K/512K Rechambered into Plus Case fork of this thread?
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I think what you've added about that RAM is interesting I'll have to look and see if they hid anything underneath the boards as well.
HRMM, can't think of a good reason to bodge an all thruhole board's solder side, what with every signal available on the component side?
Morning musings have me reconsidering that SIMM notion. Was a flight of fancy that wouldn't look right even if far less work. Was originally thinking a pair of daughterboards, but installing 512K and gating that spider infestation might be workable?
Rearranging components east of the Plus repositioned cable connector is something I'll need help with from someone schematically literate. Plus chip count was dropped to four from six on the 128K, discounting the redundant SCSI Controller.
I've been trying to follow the CLK(RTC) discussion. Are you saying the Plus part is not backward compatible for this project? If is is that's great. If not, can a circuit be dropped into the board layout to make use of it if a replacement for the 128K part can't be found? That would be better anyway in terms of Plus parts cannibalization. No additional cost for replacement RTC, no?
Morning musings have me reconsidering that SIMM notion. Was a flight of fancy that wouldn't look right even if far less work. Was originally thinking a pair of daughterboards, but installing 512K and gating that spider infestation might be workable?
Rearranging components east of the Plus repositioned cable connector is something I'll need help with from someone schematically literate. Plus chip count was dropped to four from six on the 128K, discounting the redundant SCSI Controller.
I've been trying to follow the CLK(RTC) discussion. Are you saying the Plus part is not backward compatible for this project? If is is that's great. If not, can a circuit be dropped into the board layout to make use of it if a replacement for the 128K part can't be found? That would be better anyway in terms of Plus parts cannibalization. No additional cost for replacement RTC, no?
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@max1zzz Would your your ROM-inated Plus tweak work (or in any way be beneficial) for 128K-512K Rechambered project?
68kmla.org
Have you got that one tested yet?
Reverse Engineering the Macintosh Plus PCB
After a long wait i have finally sent the ROM-inated design off for manufacture, I might have got slightly distracted with the LC boards...... (And wanted to get these boards in before i get distracted with my next board! :) ) Hopefully I should have the boards in the next week or two
68kmla.org
Have you got that one tested yet?
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It should work just fine in a 128-512k board as it's literally just the original Rom-inator design basked onto a plus logicboard (and thus could be baked into any other board the original design supported)@max1zzz Would your your ROM-inated Plus tweak work (or in any way be beneficial) for 128K-512K Rechambered project?
Reverse Engineering the Macintosh Plus PCB
After a long wait i have finally sent the ROM-inated design off for manufacture, I might have got slightly distracted with the LC boards...... (And wanted to get these boards in before i get distracted with my next board! :) ) Hopefully I should have the boards in the next week or two
Not quite yet, I only got the boards in January so you can't expect me to finish them that quickly!
On a more serious note - the test board is 95% assembled, just need to get around to lugging the 512k out the loft to test it....
LOL! I hear that! On a side note, have you been able to make time to reverse any of your board layouts that we've talked about into KICAD schematic form?Not quite yet, I only got the boards in January so you can't expect me to finish them that quickly!
Not yet, well I started the LCIII and got about 2/3 of the way through the schematic then got lost down the "ooh there's two extra RAS signals" rabbit hole
72-pin SIMM on 128K <=> Plus doesn't make as much sense as on SE/30, because memory usage on the 128K/Plus is only 16 bits wide and 72 pin SIMM is 32 bits wide.
It would make more sense to just populate with fewer, higher density chips, assuming the refresh circuitry is compatible. Four 2M X 4 DRAM chips would give you 4MB of RAM in just four chips. Actually not sure that's compatible with whatever bank structure the Plus used. It might need to be eight 1M X 4 chips in two banks.
There are some X8 and even some X16 DRAM chips out there. They were used to populate the PM6400 on-board DRAM, e.g.. So one could possibly get the memory down to single 2M X 16 DRAM chip, but then you'd be designing a board to use a memory chip that is sort of rare.
It would make more sense to just populate with fewer, higher density chips, assuming the refresh circuitry is compatible. Four 2M X 4 DRAM chips would give you 4MB of RAM in just four chips. Actually not sure that's compatible with whatever bank structure the Plus used. It might need to be eight 1M X 4 chips in two banks.
There are some X8 and even some X16 DRAM chips out there. They were used to populate the PM6400 on-board DRAM, e.g.. So one could possibly get the memory down to single 2M X 16 DRAM chip, but then you'd be designing a board to use a memory chip that is sort of rare.
Yep, figured we'd be wasting way more than just the "other" 16 data lines. What's the lowest capacity 72pin SIMM extant? If one were but 2MB we'd still be wasting 3x what we'd be using besides that MB on the wrong side of the bus.
@Trash80toG4 - in case you hadn't seen, the RTC has finally been reverse engineered and implemented in an ATTiny85 (SOIC) on a carrier PCB.
Thanks , Kai, been looking at that topic listing and been excited about it having been done! Right now I'm trying to get on track to have the flood destroyed missing carpet replaced in my second bedroom, so just randomly tossing my crazy notions about here or there in all the usual places.
Excited a bit about having documented the recent upgrade of the swing arm 42" Flat panel mount on my TelCo Rack. It now does over 180 degrees!
This thread will be way down the line for the new year, but such is my life!
Excited a bit about having documented the recent upgrade of the swing arm 42" Flat panel mount on my TelCo Rack. It now does over 180 degrees!
This thread will be way down the line for the new year, but such is my life!
Thanks , Kai, been looking at that topic listing and been excited about it having been done! Right now I'm trying to get on track to have the flood destroyed missing carpet replaced in my second bedroom, so just randomly tossing my crazy notions about here or there in all the usual places.
Excited a bit about having documented the recent upgrade of the swing arm 42" Flat panel mount on my TelCo Rack. It now does over 180 degrees!
This thread will be way down the line for the new year, but such is my life!
Sorry to hear about you having to deal with flood damage, T80.
Thanks, it's been two years since the first one in June, and a few months ago for the second one. Crappy old CPVC pipes in an apartment building, Spindleresque plastics used for hot AND cold lines.
My water heater went after I moved in 11 years ago and was likely here a lot longer than that.
Let my unfortunate experiences be a warning for planning storage and equipment in basement workspaces. I'm ground floor on a slab so water level would have topped out at transition/saddle of the doorways. Thankfully it wasn't an eight foot deep concrete bowl._______________________________________________
Be that as it may and back on topic, who's got links to affordable filters for this? I'm assuming they'll be good for MEK/Acetone and such as well? Hydrocarbon molecules should be larger than lead fumes I'd think?
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Thanks, it's been two years since the first one in June, and a few months ago for the second one. Crappy old CPVC pipes in an apartment building, Spindleresque plastics used for hot AND cold lines.
My water heater went after I moved in 11 years ago and was likely here a lot longer than that.
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Be that as it may and back on topic, who's got links to affordable filters for this? I'm assuming they'll be good for MEK/Acetone and such as well? Hydrocarbon molecules should be larger than lead fumes I'd think?
Man, you are talking my life. Just a few years ago I had my well pump fail, so I had to have that replaced. The well pump had been apparently failing for a long time and lowered the pressure in the inflow lines to the house. So when the well pump was replaced and began operating at full power it caused a pipe that was badly corroded to rupture and produce maybe a quarter inch square hole through which water was arcing about 6 feet in the air and every so slowly flooding the basement. Given the small pressure reduction such a small hole would create it went completely unnoticed by the person I had pet/housesitting while I was away for work for two weeks. When I got back I asked them if everything was ok and they said "Yeah. The only strange thing is that your well pump has been running non-stop for the last few days, but everything seems to be fine"
Given that I knew that a well only pumps when water is being removed from the system I ran down to the basement and there was about 2 feet of standing water covering the floor of the entire basement. I went over to the well piping and saw the arc of water and immediately shut off any more water flowing in, however, the hole was beyond the shut-off valve on the house side of the piping. As such, there was literally no way to stop it from draining all the water from the house and into the basement.
I made an insurance claim and fortunately it covered all the damage and recovery.
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As far as any kind of filter, if you want it to trap lead fumes and organic molecules you'd need to use something that is active carbon and has a rating of at least MERV13.