LisaList2

Advanced search  

News:

2019.06.07 fixed NChat for the "Curve" theme, will eventually move it to its own page and add it to the default theme as well. Other plugins are next. see post in the Meta board for details

Pages: [1]   Go Down

Author Topic: 512k to 2MB RAM board mod?  (Read 152 times)

blusnowkitty

  • Sr. Member
  • ****
  • Karma: +33/-0
  • Offline Offline
  • Posts: 105
512k to 2MB RAM board mod?
« on: March 10, 2021, 03:15:12 pm »

https://lisafaq.sunder.net/lisafaq-hw-intro_introduction.html

In 3.3.1 it quickly mentions off-hand that the Apple 512k board can be modified to 2MB. Anyone know where to look for more details on this? I've found a good deal on another 512k board and I'd like to try it out.
Logged
You haven't lived until you've heard the sound of a Sony 400k drive.

Lisa2

  • Administrator
  • Sr. Member
  • *****
  • Karma: +24/-0
  • Offline Offline
  • Posts: 50
  • See why 1983 was more like Y2K...
    • Lisa2.com
Re: 512k to 2MB RAM board mod?
« Reply #1 on: March 10, 2021, 03:30:36 pm »

Logged

blusnowkitty

  • Sr. Member
  • ****
  • Karma: +33/-0
  • Offline Offline
  • Posts: 105
Re: 512k to 2MB RAM board mod?
« Reply #2 on: March 10, 2021, 03:42:03 pm »

Nice, so it looks like all I need to do is get enough RAM chips to bring the board up to 2MB, reroute a few traces, and stick it in the high slot?
Logged
You haven't lived until you've heard the sound of a Sony 400k drive.

sigma7

  • Administrator
  • Full Member
  • *****
  • Karma: +31/-0
  • Offline Offline
  • Posts: 35
  • Warning: Memory errors found. Verify comments.
Re: 512k to 2MB RAM board mod?
« Reply #3 on: March 22, 2021, 02:27:17 am »

Nice, so it looks like all I need to do is get enough RAM chips to bring the board up to 2MB, reroute a few traces, and stick it in the high slot?

Yes, plus the 74LS14 and LS157.

Desoldering the old RAM is by far the hard part (I suppose finding 72x 41256 DRAM chips will someday be harder).

If you can stand destroying the old chips -- cutting before desoldering (at least the power pins) is likely to save some headaches and minimize damage to the board.
Logged
Warning: Memory errors found. ECC non-functional. Verify comments if accuracy is important to you.

blusnowkitty

  • Sr. Member
  • ****
  • Karma: +33/-0
  • Offline Offline
  • Posts: 105
Re: 512k to 2MB RAM board mod?
« Reply #4 on: April 04, 2021, 04:40:25 pm »

Desoldering the RAM proved to not be that big a challenge, I just blasted the joints with a hot air gun and everything came out easily. I am going to buy a desoldering gun though, cause manually cleaning out literally 1,000 pin holes by hand with an iron and wick is just way too much work.

I didn't see any S14s or LS157s, but according to the PDF I need to work on U10E, the S10 at the bottom of the board, left hand side of the edge connector in between C86 and RP6, and remove U14A next to C5 at the very top of the board if I'm reading this right?
Logged
You haven't lived until you've heard the sound of a Sony 400k drive.
Pages: [1]   Go Up