| HP codename, series |
Merlin, Classic |
| Type, Precision, Input Mode |
Scientific, 10 BCD digits, exponent ±99,
Reverse
Polish Notation |
| Programmable |
Unmerged instructions, no editing, no
subroutines, no
symbolic labels.
|
| Performance
Index |
1.0. One of the slowest computers in my
collection. |
| Memory |
20 registers, 49 program steps |
| Display |
13 digit 7 segment red LED plus sign |
| Special features |
Built-in accurate quartz timer, linear
regression, many
conversions. The timer software was present in the HP-45 as well but wasn't officially
supported
due to the lack of an accurate crystal. Once in timer mode (enabled by a switch below the display), the
following
commands are available:
- R/S toggles timer between running and stopped.
- CLx resets the timer to zero both in stopped and
running mode.
- EEX turnes on/off the 1/100th second display.
- 1 - 9 stores the current time in the corresponding
register
when the timer was running or recalles the stored time when the timer
was
stopped.
|
| Original Pricing, Production |
1.1.1975 ($395) - 3.1.1977 ($335)
DM 1150 in 1976 (according to Kurt Pribil).
|
| Batteries |
3x AA pack or AC power supply |
| Dimensions |
Length 15.1cm, Width 8cm, Height 3.6cm |
| Links |
HP-55
Owner's Handbook (PDF, English, 108 pages, 2/1975)
HP-55
Kurzanleitung (PDF, German, 33 pages, 12/1974)
Quick Reference (PDF) |
| Comment |
HP's sixth calculator and the second
programmable
after the HP-65. It's outstanding
feature
is the built-in timer with its support for up to 10 split time
measurements.
Other than that pretty straight forward with a quite poor programming
model
similar to the HP-25C. |
| Registers used for summation and linear regression:
| R0 | R1 | R2 | R3 | R4 | R5 | | n | Sum(x) | Sum(x²) | Sum(y) | Sum(y²) | Sum(x*y) |
|
