HP42S Up and Down arrow symbols on 82240B

[tcab]

The HP42S uses arrow symbols for moving around a matrix

←
↑
↓
→

I'm wondering how the ↑ and ↓ characters manage to get printed on the HP 82240 printer, since those characters seem to be missing from the Roman 8 character set, or more specifically the Modified HP Roman-8 (1986), variant II (HP 82240A/B & HP-28C/S). Those characters should be printed when embedded in program listings, or I think, when the HP42S/Free42 is in trace mode...


Notice the left and right arrows in the middle of line five. But I cannot see the up and down arrows, so how are they printed?

I don't have a HP42S (though I do have a DM42 which runs Free42), and my 82240B has broken, so I can't investigate this further myself.

[Didier Lachieze]

↑ is printed as ^ for example X↑2 is printed X^2
↓ is printed as v for example R↓ is printed Rv

Here is the printout of :

Code:

01 X↑2
02 R↓
03 ↑
04 ↓

on the 82240B, from the HP-42S

[PANAMATIK]

(03-01-2018 10:52 PM)tcab Wrote:  I'm wondering how the ↑ and ↓ characters manage to get printed on the HP 82240 printer...

The HP82240B printer has two character sets, Roman8 and ECMA. The up/down arrows are in the ECMA set. An ESC sequence can switch between the two character sets. But the above printout shows the HP-42S doesn't make use of it, I think it was designed for the HP82240A printer, which had only one character set.

Bernhard

[tcab]

Interesting. Yes I can see all four arrow direction symbols in the ECMA-94/RPL character set, in positions 141,142,143 & 144.