HP 71B RAM: has anybody big ones to sell?

[KimH]

(06-18-2021 04:51 PM)Dave Frederickson Wrote:  

(06-18-2021 03:29 PM)Valentin Albillo Wrote:  The very best combination for me, the one I've been using for decades and which I refer to as a "Power HP-71B" consists of:

- HP-71B, of course, 16 Kb RAM built-in

- HP-IL ROM, for I/O and boolean functions

- Math ROM: complex numbers and operations, matrix operations, hyperbolics, Polynomial Solver, 5-level general Solve, 5-level Integrate, FFT, etc, etc.

- JPC ROM: structured programming (REPEAT..UNTIL, WHILE..END WHILE, LOOP, nested IF, SELECT..CASE), number-theoretic functions (PRIM, FPRIM, NPRIM, etc), advanced string functions (REPLACE$, etc), time-date functions, formatting function, and many many many more.

- STRINGLX LEX: essential string functions (RPT$, TRIM$, ROT$, etc)

- CMT 128 Kb RAM in the card reader port

and a couple of smaller RAM modules in the front ports, just because they're spares.

This setup provides me with in excess of 160 Kb of RAM, which for the relatively slow HP-71B is more than enough, and I've never filled the memory up despite having 100+ BASIC programs in the machine and frequently using large arrays, matrices, and strings (up to 64-Kb strings can be manipulated).

I heartily recommend you to get such a power setup and forget about "maximum RAM", your capabilities will increase much more by having the Math and JPC ROMs instead of hogging the address space with unneeded RAM, which actually might significantly slow down your machine.

V.

This looks like a very expensive setup. I'd guess the 128k RAM would cost around $400 even if you could find one. On the other hand, for $400 I'll bet someone would sell a FRAM71. With that you could add the MATH 2B ROM, a customized JPC ROM, upgrade a 1A HP-IL module, upgrade the 71B O/S to 3cccc, and have tons of RAM.

Dave

I agree with Valentin, that would also be my preferred set-up plus a small LEX I have added to the STRINGLEX, we all have our favorites, buckle up for feedback on that one let’s see them..

Ideally JPC, MATH (1 or 2) and the lex would be in a 64k EPROM, which is in planning, need access to the P01, and have a plan once the pandemic gets under control.

Today I have them in several different configurations
- 2*32k Port-RAM with a small MLCC cap to “keep them alive” when switching to another machine
- CMT-HHP-FRAM versions in the card reader port.
- JPC/MATH eprom I found on eBay here in Germany, another enthusiast separated from his “loved toys”, which was my luck.

Maybe I can build a 160k as the one Matthias has, I recall that there is a description which gets me halfway there… another one for the “rainy day-list”

Thanks again to Sylvain for the amazing Compendium - @FLOPPY, this is one you can enjoy for days if you’re into understanding what the 71B is capable of!