Maximize a 41C - Challenge

[rprosperi]

(04-24-2023 06:31 PM)pier4r Wrote:  Not having a 41C, could I get a small explanation of this? Do I understand correctla that those blocks are - as the name suggest - port extenders for functions, like a JBOD ?

If that is the case, then the 41C was really designed as a sort of small compact monstrous controller? If I am not wrong the 41 should have the possibility to control devices through a bus (HP IL or the like). I mean amazing, they tried to make a portable super control plane. But was the calculator able to use all the ports or only 4 at times?

No 41C ???? My son, you are missing an essential component of being a true HP aficionado....

Each physical 41 Port is connected to 2 logical Pages; the 41C ROM memory is comprised of 16 pages (0..F) of 4K 10-bit words.

41 OS ROM is installed in Pages 0-3
Page-4 is reserved for Diag ROM (or other, special-purpose ROMs which are hard-coded to Page-4)
Pages 5, 6, 7 have no physical ports, and are somewhat 'reserved' for special-purpose ROMs which are hard-coded to load in these pages exclusively. If these devices are not installed, these Pages can be used by normal ROMs, if they are configured to map into these Pages)

Port-1 maps to Pages 8 & 9
Port-2 maps to Pages A & B
Port-3 maps to Pages C & D
Port-4 maps to Pages E & F

The Port-X-Tender lets you install multiple ROMs, which can fit logically into the available Pages, but not physically, due to lack of Port slots.

Example: You can plug 2 4K ROM modules, one into Page-8 and one into Page-9 using the Port-X-Tender, but this isn't possible on a 41C as there is only Port-1 physically available.

Note: The above is only a gross simplification of the full details, and no doubt some of these will come in follow-up posts, but this is intended to explain the broad purpose of the Port-X-Tender.

The Port-X-Tender manual, which explains this FAR better than these short notes, can be found here, and is well worth reading by all 41 users. Nearly all readers will have a bit of an "A-Ha!" moment when reading this manual, written by Jake Schwartz!)

https://literature.hpcalc.org/items/1259