how can i upgrade the ram chips on the sega gen 1 model / or any model ?
how can i upgrade the ram chips on the sega gen 1 model
- Thread starter ps3repair1981
- Start date
ExCyber said:
well what i mean by upgrade/repair the bad chips out of there is there any way to find out what chips can be upgraded or not ??? and do i have to reprogram a specific chip to make it work with the games
also i found this
Sega Genesis
CPU: Motorola 68000 at 7.61 MHz
1 MByte (8 Mbit) ROM Area
64 KByte RAM Area
Co-Processor: Z80 @ 4 MHz (Controls PSG & FM Chips)
8 KBytes of dedicated Sound Ram
64 simultaneous colors of 512 color pallete.
Pixel resolution: 320 x 224
VDP (Video Display Processor)
64 KBytes of dedicated VRAM (Video Ram)
64 x 9-bits of CRAM (Color RAM)
3 Planes: 2 scrolling playfields, 1 sprite plane
Sound
PSG (TI 76489 chip)
FM chip (Yamaha YM 2612)
6-channel stereo
8 KBytes RAM
Signal/Noise Ratio: 14dB
Sega CD
System Specs
Processors Memory
Motorola 68000 at 12.5 MHz
6 Mbit Main RAM
512 Kbit PCM Samples
64 Kbit Internal Backup RAM
128 Kbit CD-Rom cache
Storage Medium Audio
500 MB CD-Rom (About 61 minutes of Audio)
CD-Rom Speed 150Kbytes/s (1X)
Stereo PCM Sound
32KHz (44.1 KHz for CD) Max Sample Rate
8 sound Channels
16 Bit DAC
Input to allow Stereo sound on Model 1 Genesis
Sega 32X
System Specs
Processors Memory
Two Hitachi 32-Bit RISC Processors at 23MHz
32X VDP
Z80 and 68000 from Genesis
4 Mb RAM
Storage Medium Audio
16 or 32 Mbit cartridge
CD-Rom Speed 150Kbytes/s (With Sega CD) (1X)
Stereo PCM Sound
Audio Mixing with Genesis Sound
8 sound Channels
Chilly Willy
Established Member
Look at the ram chips currently on the PCB. Then go to the net and find chips that are compatible. If you need more instruction than that, you should probably take it to someone who knows what they're doing.
Chilly Willy said:
ok but i am not a programer at all really . what kind of equipment i need to add the reflash the old chips over to the new ones that is really my question ?
Chilly Willy
Established Member
ps3repair1981 said:
This isn't a job for a programmer - at no point will changing the ram require writing any code.
This is a job for an electrical engineer... you need to ID and desolder the old ram chips, then solder in new compatible ones. To desolder the chips, you need a soldering iron and a solder sucker (although you can also use solder wick, it won't do as good a job as a sucker). To solder in the new ones, you need a soldering iron and solder. These items will run you between $50 and $100 on the low end, and several hundred dollars on the high end. You'll also need to practice, so count on destroying a several boards while you develop the skills needed.
Seriously, Dude, this is not something you should be doing on your own if you don't know what you're doing. Take it to someone who does, and already has all the right equipment. Not having the equipment, or even knowing what is required, should be a BIG TIP that you shouldn't be attempting it yourself.
Chilly Willy said:This isn't a job for a programmer - at no point will changing the ram require writing any code.
This is a job for an electrical engineer... you need to ID and desolder the old ram chips, then solder in new compatible ones. To desolder the chips, you need a soldering iron and a solder sucker (although you can also use solder wick, it won't do as good a job as a sucker). To solder in the new ones, you need a soldering iron and solder. These items will run you between $50 and $100 on the low end, and several hundred dollars on the high end. You'll also need to practice, so count on destroying a several boards while you develop the skills needed.
Seriously, Dude, this is not something you should be doing on your own if you don't know what you're doing. Take it to someone who does, and already has all the right equipment. Not having the equipment, or even knowing what is required, should be a BIG TIP that you shouldn't be attempting it yourself.
ok thank you . but i am really good doing soldering . see what i do i do repair ps3 and psp but i want to also go into fixing the old systems .
Chilly Willy
Established Member
ps3repair1981 said:
Ah, okay. I guess you probably CAN do it then.
Okay, to make it easier - the MD uses PSRAM chips for the main memory. So when you check out the ram, if it's not PSRAM, it's not the work ram, it's the vram for the video. As the work ram IS PSRAM, you need to replace the chips with PSRAM as the MD does not generate refresh cycles to the PSRAM. So DRAM will not work in its place.
Truthfully though, you'll probably never run across a MD with bad ram - by far the most common problem you'll see is bad caps. The next most common problem would be a bad power regulator.
It's been some years since I looked at this, but did those chips actually have muxed address pins like DRAM? Otherwise in principle it would make sense to just cut the crap and replace them with SRAM, since modern PSRAMs are mostly high-density low-voltage chips made for cell phones.
Any chance you can refresh my memory on this? (but wait, that shouldn't be necessary
)
Any chance you can refresh my memory on this? (but wait, that shouldn't be necessary
Chilly Willy
Established Member
ExCyber said:It's been some years since I looked at this, but did those chips actually have muxed address pins like DRAM? Otherwise in principle it would make sense to just cut the crap and replace them with SRAM, since modern PSRAMs are mostly high-density low-voltage chips made for cell phones.
Any chance you can refresh my memory on this? (but wait, that shouldn't be necessary)
No, they're usually nothing like DRAM. They're actually usually compatible with SRAM packages, but the OP should check these things directly by looking up the chip datasheets to be certain.
Chilly Willy said:
is there a way if i put new chips do i have to program the sega bios ???
Chilly Willy
Established Member
ps3repair1981 said:
The "BIOS" in newer MDs does nothing more than show a SEGA logo and start the cart. There is nothing like a library, and no existing games will take advantage of more ram. The MD has room for up to 2 MB of work ram, and I'd love to have that in my own MD, but that would only affect homebrew which could test for the extra ram and make use of it. Existing games assume there is only 64 KB and that's it.
