HP 2112A

[J. David Bryan]

On 4 Feb 2007 at 19:36, Richard Lynch wrote:

> There are several numbers on the center board:
> 5080-9740
> 5060-8380
> A-3516-22
> 809L
> Here's a photo of its ROMs:

The ROM part numbers and the board number (5060-8380) show that the board 
is a "Fast FORTRAN Processor II" microcode set.  This contains the FFP 
instructions plus the dynamic mapping instructions (DMI) that work with 
your MEM board in the front card cage.

If that's the only microcode board under your CPU, then you're missing the 
base instruction set board, which must be present to use the machine.  The 
machine should power up, but the front panel won't work, as that's 
controlled by microcode on the base set board.

This board appears on page VI E-4 of the HP 1000 Engineering and Reference 
Document, available here:

  http://www.bitsavers.org/pdf/hp/1000/1000_MEF_EngrRef/


> The three ROMs all have 12992 on them, the first in light pencil (not
> visible in the picture below)...

Is it 12992-something?  The "something" will indicate what ROM it is.


> ...the others with a label as shown here: 
> 
> http://home.comcast.net/~richardlynch3/hp/opt_roms.jpg

>From the photo, the installed ROMs are:

 - U36 (ROM #0) 1816-0420 is the 12992K paper tape loader
 - U16 (ROM #1) is unknown
 - U15 (ROM #2) 12992-80009 is the 12992C 264x CRT tape cartridge loader
 - U13 (ROM #3) is the same as #2

U16 does not appear to have an HP part number on it, although your first 
message said that it was a disc boot loader.  The HP part number might be 
on the underside; you might wish to remove it from the socket to check.  Or 
the fact that the "chip label" is in pencil might indicate that it's a copy 
of the HP chip that was made by the owner.  Or it might be a custom disc 
boot loader.

U15 and U13 are designed to boot from the DC-100 minicartridge tapes that 
are present in (most) HP 264x-series terminals, e.g., the 2644, 2645, 2647, 
or 2648.  A 12966A or 12968A interface card must be used with these 
terminals when using the 12992C boot loader ROM.


> Why are U13 and U15 both labeled "80009"?  Are they the same chip or is
> that a date code? 

Same chip.

Section 7 of the "HP 1000 MEF CE Handbook" has tables of board/chip part 
numbers and associated descriptions that will help to identify these sorts 
of things:

  http://www.bitsavers.org/pdf/hp/1000/5950-3767_M-E-F_CEhbk_Jul84.pdf


> I'm not sure if the paper tape loader ROM is present.  U12 is empty - is
> this where it was supposed to go: 
> 
> http://home.comcast.net/~richardlynch3/hp/u12.jpg

It's U36, visible in your "opt_roms.jpg" image; see page 13-8 of the CE 
Handbook above for a locator diagram.


> One more photo of the numbers on the CPU board:
> 
> http://home.comcast.net/~richardlynch3/hp/cpu_nums.jpg

The board number, 5060-8352, indicates that it is an M-series CPU with date 
code 1838 (38th week of 1978).

                                      -- Dave