Upgrading HP48G



#9

It's me again... I've found a few ram chips which have almost all the right specs I need. The problem is that they (all the 128kB x 8 types) come in 1 Mbit modules and that's the smallest I can find from non-minimum-order companies (e.g. futurlec.com or digikey.com -- digikey has a $5.00 charge for orders below $25 which I can handle)

So my question is, would there be problems if I were to use a 1Mb sram module for the initial 128kB upgrade? I wish I could post to comp.sys.hp48 but I currently do not have a news server. Anyway, any help would be truly appreciated.


#10

Hi H.D. Can yu tell me what the par number is for the chips you have?

By typing a few (address buss) pins low on the chips you can get
the ran to operate happily as a 128 kB device.

BTW, whats the part number for the original chips, too?

DW


#11

I ended up buying (from Digi-key):

M5M51008DFP70HIA0-ND	IC SRAM 1MBIT 70NS 32SOP
PT100KXCT-ND RES 100K OHM 1W 5% 2512 SMD
PT47KXCT-ND RES 47K OHM 1W 5% 2512 SMD
568-1379-1-ND IC GATE NAND QUAD 2INPUT 14SOIC
296-1195-1-ND IC HEX D-TYPE FLIP-FLOP 16-SOIC

What I was failing to realize was that when these companies list the modules as 1 M or 1 Mb, it stands for a mega-bit, which is equivalant to 1,000,000 bits / 8 ~ 128kB. I, for an incredibly and stupidly long time, kept thinking these were 1MB (as in mega-byte) modules. Anyway, the memory was "LL" but the datasheet did say low active and low idle power; the currents were comparable to one by Sony, listed as CXK581000AM-70LL

I picked up an extra 104 SMD resistor (the 100k ohm one) to upgrade the IR receiver.

As for the original 32kB memory chip on my HP48G, it's Winbond W242575-70LL.

Also, it appears that my PCB board has a number printed on it: NI9803 (printed slightly near the center of the board). I also see another number: I34 slightly below the CPU. I am hoping someone knows something about how to place the 104 and 143 SMD resistors as according to an upgrade doc I read, their alignments vary depending upon PCB versions.

I've upgraded an HP48G before (only to 128kB user ram) but it was stolen when I was studying abroad in Hungary. I finally bought a new 48G (for $15.00!) and decided to go for port 1 and port 2. This time around, I managed to open the case without any damage whatsoever (e.g. no cutting or removing the keyboard overlay) by popping the rivets (they're not damaged and are reusable) and slowly applying pressure to the latch points. I'll document the process and have plenty of photos in case people are interested.


#12

Hi HD.

I can't seem to find data on the ram you bought.

Also, please note that RAM can be electrically organized in a variety of ways, the most common ones being:
1 bit wide, 8 bits wide, 16 bits wide.
I have worked with 4 bit wide and 32 bit wide ram as well as the above.

Your safest bet is to get something which is pin for pin compatible and timing compatible. Don't forget voltage too, but this is pretty standard...

DW

Edited: 20 Sept 2005, 5:39 a.m.


#13

The ram is actually M5M51008DFP-70HIA0 (manufacturer's number). You can read the PDF here:

http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=559&M=M5M51008DFP-70HIA0

#14

Just a software guy here, but 1 Mbit = 128 Kbytes, right? Is it a matter of how they are arranged behind the address decoding logic?

Also, you can post to Usenet through Google Groups. It just takes a free account.

Edited: 20 Sept 2005, 1:25 a.m.


#15

Yes, Howard, of course. I must have been asleep. maybe HD has the right parts already...

DW

#16

You could always use http://groups.google.com/group/comp.sys.hp48/ for the newsgroup. You can also use Google to search the archive of the newsgroup.

Regards,
James


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP48G Series Connectivity in a USB World Les Wright 3 198 05-06-2012, 01:29 AM
Last Post: Reth
  HP48G purchase from "that list site" Ethan Conner 2 159 08-27-2011, 07:31 PM
Last Post: Ethan Conner
  HP 50g - Make menus more like HP48g Brian K 1 129 07-18-2011, 02:43 PM
Last Post: Brian K
  Backing up several HP48G/G+/GX via HP50 Thomas Chrapkiewicz 4 242 02-14-2011, 11:39 AM
Last Post: Tim Wessman
  Hp48G top plastic cover bent? Luis Moreno 3 156 05-26-2010, 04:42 PM
Last Post: Bart (UK)
  HP48G ROM transplanted in a HP38G Thomas Chrapkiewicz 0 86 08-11-2009, 12:49 PM
Last Post: Thomas Chrapkiewicz
  HP48G Problem Jno. Greenslet 7 256 06-17-2009, 08:31 PM
Last Post: Jno. Greenslet
  Troubles connencting Conn4x <--> HP48G Matti Övermark 6 254 05-29-2009, 04:30 AM
Last Post: Matti Övermark
  Upgrading memory of Pioneer models - other than 42s Jeff Kearns 3 150 10-18-2008, 02:05 AM
Last Post: Karl Schneider
  SysRPL question (HP48G-series) Matti Övermark 1 129 07-24-2008, 11:16 AM
Last Post: Matti Övermark

Forum Jump: