HP-85 ROM Pin Configurations



#2

Does anyone know what the pin configurations are for the HP-85 ROMS? Is there any documentation to describe how the HP-85 communicates with the ROM modules? It would be an interesting project to develop a "programmable ROM drawer" but possibly hold many ROM images like the MLDL2000 or clonix. Please let me know if you have ever seen documentation for such or have successfully built one.


#3

The circuit diagrams of the HP-85 are included in the service manual of the HP-85 in the MoHPC CDROM collection.

Here are the option ROM pinouts:

   ___________________
/ \
| BX4 BX3 |
| BX5 BX2 |
| BX6 GND |
| BX7 BX1 |
| -RC BX0 |
| VGG (+12V) VBB | (-5V)
| VDD (+6V) -WrX |
| f12 (phi 12) -RdX |
| f21 (phi 21) -LMAX|
| f1 (phi 1) -PWO |
| f2 (phi 2) -PWO |
|___________________|

PWO: Power On Signal
LMA: Valid Address on Bus
Rd: Read Data
Wr: Write Data
RC: ???

____ ____
| | | |
| | | |
f1: _| |___________________| |__________________________

____ ____
| | | |
| | | |
f12: _______| |____________________| |___________________

____ ____
| | | |
| | | |
f21: _____________| |____________________| |_____________

____ ____
| | | |
| | | |
f2: ___________________| |____________________| |_______

Note that the logic is 6V and the clocks are 12V !!!

The ROM pinouts are all the same, the ROM socket pins are also all the same. Each ROM selects itself if it sees its id . This is the reason that if you plug two (say) I/O ROMS, you may damage your HP-85.

**vp


#4

Would the 2708 EPROM work? It has the 12V, -5V but it only has a +5v. The spec states that that it would accept 5.25v max. Do you know of an EPROM that would compare to this HP-85 specification?
Thanks,
Jeff


#5

JeffD wrote:
> Would the 2708 EPROM work?

Sorry, the HP ROMs have a lot of logic built into them.
They are rather comparable to the HP-41 ROMs where you actually need a microcontroller to emulate the ROM.

Alternatively you may use a programmable ROM drawer
(HP 82929A)

http://www.series80.org/Manuals/HP82929A.pdf

Unfortunately they are rather rare and fetch a high price on eBay (latest one went for $159.25, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5128991233)


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP 85 Serial Interface; INPUT Example? inaki 1 394 06-12-2013, 11:09 PM
Last Post: Paul Berger (Canada)
  9815 data cartridge drive (also 9825 / 9845 / 85 / 87, and who knows what else) John Ioannidis 2 463 06-12-2013, 07:20 PM
Last Post: Craig Ruff
  HP85 Programmable ROM cardtridge 82929A-service ROM not working- inaki 2 550 04-25-2013, 08:08 AM
Last Post: inaki
  shelf life time of a ROM, EEPROM, EPROM vs Mask Rom Guido (Canada) 6 801 01-11-2013, 04:09 PM
Last Post: Thomas Falk
  Hp85 PRM-85 board Roe Peterson 2 418 12-08-2012, 12:00 PM
Last Post: Roe Peterson
  HP-85 Display Error on startup hogelmann 3 427 11-19-2012, 10:57 PM
Last Post: Paul Berger (Canada)
  HP 85 for sale from german company cdtmbu 0 281 11-14-2012, 01:22 AM
Last Post: cdtmbu
  Big ROM - 41 System DEMO ROM Ángel Martin 5 747 10-16-2012, 05:28 AM
Last Post: Ángel Martin
  HP 85 Tape. robertoataulfo 1 340 05-03-2012, 06:32 PM
Last Post: Katie Wasserman
  HP-85 Keyboard Repair aj04062 1 331 03-18-2012, 03:23 PM
Last Post: Paul Berger (Canada)

Forum Jump: