03-18-2024, 05:08 PM
Did HP ever sell a memory module for the HP-75C of more than 8K? If so what was the part number? If not, were there third-party module makers? I'd like to maximize the RAM on my 75C.
(03-18-2024 05:08 PM)toml_12953 Wrote: [ -> ]Did HP ever sell a memory module for the HP-75C of more than 8K? If so what was the part number? If not, were there third-party module makers? I'd like to maximize the RAM on my 75C.
(03-19-2024 03:51 AM)Dave Frederickson Wrote: [ -> ]Electronic DiscWhat part number?
(03-19-2024 09:06 AM)floppy Wrote: [ -> ](03-19-2024 03:51 AM)Dave Frederickson Wrote: [ -> ]Electronic DiscWhat part number?
(03-19-2024 09:49 AM)Dave Frederickson Wrote: [ -> ]+1(03-19-2024 09:06 AM)floppy Wrote: [ -> ]What part number?
The Expansion Pod is the 82718A. The 64k Electronic Disc is OPT #064. Usually the Expansion Pods are found with a 75 attached, like this one.
https://www.ebay.com/itm/364578500258
(03-19-2024 11:05 AM)Sylvain Cote Wrote: [ -> ]To my knowledge, there are Expansion Pods versions:
- Listed Expansion Pods
- 32KB RAM disk with modem (OPT 32) [I have several]
- 64KB RAM disk with modem (OPT 64) [I have several]
- Unlisted Expansion Pods
- 24KB RAM disk with modem [I have seen one]
- 24KB RAM disk without modem
- 32KB RAM disk without modem
- 64KB RAM disk without modem [I have one]
(03-19-2024 11:05 AM)Sylvain Cote Wrote: [ -> ][*]Unlisted Expansion Pods
- 24KB RAM disk with modem [I have seen one]
- 24KB RAM disk without modem
- 32KB RAM disk without modem
- 64KB RAM disk without modem [I have one]
(03-19-2024 12:40 PM)J-F Garnier Wrote: [ -> ]I have a 64KB unit without modem too, because I removed the modem board :-)Expansion Pod without modem from factory.
(03-19-2024 12:40 PM)J-F Garnier Wrote: [ -> ]The 24K units are surprising, why bothering to make a different version to save only 8k?My guest would be, custom units ordered by corporations, probably to save cost.
(03-19-2024 11:57 AM)rprosperi Wrote: [ -> ]I'm not sure what you mean by unlisted;Not listed in any official price lists. Special units ordered by corporations, my unit was made for AT&T.
(03-19-2024 11:57 AM)rprosperi Wrote: [ -> ]Does the one you (@Sylvain) have w/o modem have a new or standard p/n ?My unit does not have any part number on it.
(03-19-2024 01:17 PM)Sylvain Cote Wrote: [ -> ](03-19-2024 11:57 AM)rprosperi Wrote: [ -> ]I'm not sure what you mean by unlisted;Not listed in any official price lists. Special units ordered by corporations, my unit was made for AT&T.
(03-19-2024 02:10 PM)rprosperi Wrote: [ -> ].. and have just assumed they included modems, but will have to check, now that you've raised my curiosity. Thanks!
(03-19-2024 02:10 PM)rprosperi Wrote: [ -> ]Another variation, I presume from the factory, is the presence of an external speaker. Seems pretty awkward for a unit intended to be mobile, but these were early days of mobile computing...To be more precise, the presence of an external speaker "plug", in which you could insert a wired single mono ear bud.
(03-18-2024 07:29 PM)Sylvain Cote Wrote: [ -> ](03-18-2024 05:08 PM)toml_12953 Wrote: [ -> ]Did HP ever sell a memory module for the HP-75C of more than 8K? If so what was the part number? If not, were there third-party module makers? I'd like to maximize the RAM on my 75C.
Unfortunately the maximum RAM the HP-75C/D can have is 24KB.
Reference: HP-75 Service Manual , HP-75 Memory Organization, pages 2-44 to 2-46
(03-20-2024 03:40 PM)KeithB Wrote: [ -> ]Other than the keyboard and real space "bar", is there any other reason to choose an HP-75 over an HP-71?The design spirit of the two machines is different and it shows in a lot of places.
(03-20-2024 05:22 PM)Sylvain Cote Wrote: [ -> ]...
The design spirit of the two machines is different and it shows in a lot of places.
...
The HP-71B is a generational evolution of the HP-41. → Ever heard of an HP 44A (71B look-alike)
It use a new 4-bit CPU inspired by the 1-bit CPU of the HP-41, a new system architecture and a new BASIC implementation based on Minimal BASIC.
To me, the HP-71B feels like a handheld computer/calculator hybrid with great expandability.
IMHO, a minimal HP-71B system must have at least: HP-71B, 48KB+ RAM (17.5K + RAM modules), HP-IL and Math ROM.
...
(12-26-2015 10:38 AM)Massimo Gnerucci Wrote: [ -> ]From "A Guide to Hp Handheld Calculators and Computers" by Wlodek Mier-Jedrzejowicz 3rd edition 1999 p.80
Quote:The Titan was first given the model number HP-44 and was partly a follow-on to the HP-41 and partly an expanded HP-15C. As the project progressed, the calculator features of the HP-44 were subsumed into a handheld computer with a built-in calculator. Titan became a series 70 model, and was given the model number HP-71B, with the 1 derived from the HP-41. The B stood for "Basic-language computer", to distinguish the HP-71B more clearly from the HP-75C and the HP-75D.