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

[Dave Frederickson]

(06-18-2021 03:29 PM)Valentin Albillo Wrote:  

(06-18-2021 06:45 AM)floppy Wrote:  So far I am aware, 512Kb should be possible. https://www.hpmuseum.org/hp71.htm
So far, only 32k identified on eBay (I have 2 of them now; and searching for more).
Has anybody a 512Kb to sell?
Or 2x 256Kb?.. As big as possible.
Thanks.

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