ST M48T59Y 64 Kbit 8Kb x8 TIMEKEEPER SRAM reprogramming  - Page 1
Forum section: electronics / beginners

author: level3
author_rank: Newbie
timestamp: September 10, 2016, 06:41:48 pm
content: Hi Guys,I'm restoring retro Sun Blade 150 RISC computer as just for fun project, and I have issue with password lock on BIOS which is not allowing me to boot it up. I've figured out that this password stored in ST M48T59Y SRAM chip with battery backup and now I want to flash it out. I have even order USB MiniPro TL866CS programmer just for this project, but unfortunately I don't this this chip in supported list.Could you please advice which programmer should I use to erase that ST M48T59Y 64 Kbit 8Kb x8 TIMEKEEPER SRAM chip?I have plan B to physically disassemble that chip to remove battery power, but this is only as last resortThanks!

author: bingo600
author_rank: Super Contributor
timestamp: September 11, 2016, 06:35:28 am
content: Couldn't you just erase it with an external MCU ?I mean it appears as a Ram/Bingo

author: bson
author_rank: Unknown
timestamp: September 11, 2016, 07:30:11 pm
content: Try to read and write it in the TL866C as a "Standard SRAM", either 6164 or 6264. The M48T59Y does have a couple of outputs: /RST, /IRQ - which are NC and CE2 respectively on a JEDEC SRAM, but it could just work. If it isn't recognized, it's likely because of a conflict between its /IRQ output and the expected CE2 input, more specifically that it doesn't respond to CE2.

author: level3
author_rank: Newbie
timestamp: September 13, 2016, 11:42:18 am
content: Quote from: bson on September 11, 2016, 07:30:11 pmThank you for response. I've tried but it says "Address: 1FF0 Unit Test Error!"

author: bobaruni
author_rank: Regular Contributor
timestamp: September 13, 2016, 12:52:54 pm
content: That's because it's got functions other than RAM, it's a real time clock as well, for which the registers start at 1FF8hSee datasheethttp://www.st.com/content/ccc/resource/technical/document/datasheet/4c/be/f1/f8/83/9e/42/3b/CD00000522.pdf/files/CD00000522.pdf/jcr:content/translations/en.CD00000522.pdf

author: level3
author_rank: Newbie
timestamp: September 18, 2016, 11:47:47 pm
content: Quote from: bobaruni on September 13, 2016, 12:52:54 pmThank you. It must be it. Maybe you can advice if there is any way how I can change start address for TL866C programmer?

author: bobaruni
author_rank: Regular Contributor
timestamp: September 19, 2016, 11:08:10 am
content: You're welcome.Setting the address wont help you for a RAM test.I don't have a TL866 programmer but I have downloaded the software and had a quick play....The RAM device you selected is for testing only.If you want to read and write, try selecting the device as DALLAS DS1225 (RW), this should work on a M48T59Y's NV RAM section, fill the buffer with the data you require and write it.It may fail when you get to the real time clock data section but you don't care about that as you just want to fill the backed up SRAM with your own data.To mask off the clock section and prevent errors, set the address range (bottom left on the MiniPro software) to 0->1FF7.Not sure if this will work but worth trying, if this doesn't work then there are harder ways of doing this that involve wiring up an adaptor to make the M48T59Y look like an EPROM.