I have just bought myself a HHP combo 64k Ram 32k Rom (what would life have been without ebay). The RAM works great in port 5 (01 & 02) and it even tells me with SHOWPORT that port 5.00 has 32k (type 2=ROM). Has anybody here tried to program an EPROM for HHP (or know how it's done), what type EPROM is it 27256?.

I have considered using it as a hardwired or memory mapped I/O.



My Hand Held Products brochure comes in Handy again! It says the following:

Using Your EPROM Carrier

If you wish to add EPROM capability to your
HP71, three different Memory Modules are

* 32K EPROM Carrier
* 32K EPROM Carrier with 32K RAM
* 32K EPROM Carrier with 64K RAM

EPROM functions are identical in all three
You may install up to 32K of EPROM in your
71M/M EPROM Carrier. The Carrier will accept the
following: Intel compatible, CMOS, 27256, 200
nanosecond or faster.

Addressing the Memory ...
Memory in each EPROM Carrier version is parti-
tioned in 32K increments and addressed in these

* 32K EPROM ... Port 5.0
* 32K EPROM/32K RAM ... Ports 5.0 and 5.01
* 32K EPROM/64K RAM ... Ports 5.0, 5.01, and 5.02

Programming the Memory ...
Hand Held Products offers SDS (System
Development Software) for programming your 71
M/M EPROM. The EPBURN SDS may be pur-
chased for a nominal charge if you wish to burn
your own programs into EPROM.
Hand Held Products can also perform quick
EPROM burns for you at our facilities. Call or write
if you'd like additional information on this low cost

prices (August-September 1988 discount letter):

32K EPROM Carrier - $95 reduced from $115
32K EPROM Carrier with 32K RAM - $225 / $275
32K EPROM Carrier with 64K RAM - $300 / $375
(typo - says "32K RAM/64K EPROM" - in letter only)

I have a Psion Organizer which comes in a slide-out case, has a two line LCD display and a rectangular-array keyboard and runs on a 9V battery. I bring it up because one of the types of memory modules that can be plugged into it is EPROM modules and the Organizer has the ability to write to the EPROM. It treats it as write-once mass storage. The modules have the quartz window exposed so you can erase the EPROM and start over. Psion sold a UV source for this purpose.


Hello, Ellis;

I remember I saw a Psion Organizer that follows your description, but it happened in the 80's (earlier version?). Anyway, I remember that the owner told me (and showed me) it was able to instantly recognize modules connected to it while it was switched to ON, smoething like PCM_CIA management. Do you (or anyone else) know if this is indeed a correct procedure? I remember he showed me the current configuration and then he plugged a RAM module in and checked again the configuration: instead of EMPTY it had an 8KRAM. What I want to know if this sort of procedure is correct.

Best regards.

Luiz C. Vieira - Brazil


I would call that "hot-swapping" although that is a term usually applied to high power devices like disk drives. I don't know if that is allowed or possible with my Psion, I'll have to look for the manual and see.


I looked in the Psion Organizer manual. It never says in so many words that it is OK to plug in a module while the unit is on, but it never warns you not to, as many manuals for many products do over and over!

In some procedures, it does imply strongly that you can plug in modules without turning the machine off. For example, the manual describes invoking the procedure to save a file to the internal RAM, called device A. Without any warnings to turn off the machine, it says if you now plug in a module into the socket for device B, and press "MODE", the destination displayed for the pending operation will change from A to B. Not only that, if the module you plug in is a never-used (since erasure) EPROM module (called a "Datapak"), when you press "MODE" the machine first displays "SIZING PACK B PLEASE WAIT". "Sizing" creates the file system on a blank sevice.

So I would say the manual takes pains never to express surprise that it is OK to plug in a module with the machine turned on! It does advise against pressing any keys while inserting a module.

My machine is the Organiser II model CM (note UK spelling of "Organiser"). It is the bottom of the line with 8K internal RAM. Then there is a model XP with 32K internal RAM. Both have LCD displays with 2 lines of 16 characters. Some of my application program pack manuals mention models LZ and LZ64 which have 4 line LCD displays - maybe the LZ64 has 64K RAM?

There are three kinds of modules that can be used in the two device sockets: Datapaks, which are blank EPROMs in sizes from 8KB to 128 KB (only up to 64 KB usable with the CM), Program Packs, which are just Datapaks with commercial programs stored on them, and Rampaks which contain 32K battery backed RAM. The manual for the machine says the Rampaks come with instructions that must be read and followed before use - maybe they have a power sequencing requirement.

They must have run out of space in the mainframe ROM: it contains the trig functions SIN, COS, TAN and ATAN. The Maths Program Pack adds ASIN and ACOS! along with numerical integration, root finding, hyperbolic functions and more.

Psion calls the process of erasing the EPROM in a Datapak "Formatting" and they sold a UV light source called a "Formatter"! I don't know what they charged for the Formatter but they also provided a mail order Formatting service, charging £5 to Format one device! The price of the Datapaks was US$100 for a 64KB and $60 for a 32KB, according to an insert that came in my package. The copyright dates in the various manuals are 1986 - 1989.


Hello, Ellis;

I've been curious about Psion since I saw one of them when I was at the university. I remember I already had mi HP41 and the guy with the Psion told me he wuold never trade its Psion for an HP41. I kept that in mind, but I never saw another one again.

What about nowadays? Any e-address so I can have a look at the new models? Or Psion also quit calculators as well?

Thank you. Good, valuable information you post here.

Luiz C. Vieira - Brazil


The last I remember hearing of Psion was in the EduCalc catalog. I just looked at my oldest one (#42, 1988) and it has my model! I didn't know that, I got my Psion in a set from a closeout catalog, just out of curiosity. It has an interesting programming language like structured Basic and can be programmed in machine code (Hitachi 6303, based on Motorola 6800). The same ad is in the 1989 EduCalc catalog(#43) , then in 1990 (#48), they added the LZ models, they have 32K and 64K of RAM. EduCalc dropped some of the prices in #49 (1990). In my next catalogs, #53 and #54 (1991) they only have the LZ (32K) along with a smaller assortment of accessories than before. Then in #56 (1992) they introduce the Psion Series 3, a V30 (8086/Z80 compatible processor from NEC) based clamshell palmtop with graphics - which they have extended their OPL language to include - and an MS Word compatible word processor, 384K ROM, 256K RAM, two slots for some kind of Flash memory cards and RAM cards, QWERTY keyboard, 8 lines X 40 characters text display. The same ad is in #57 (1992) and #61 (1993), my last catalog.

Museum CD-ROM 5 has catalog #29 (1985) which doesn't have any Psion products - it pretty much only has HP and TI. BTW, it has the HPIL parts from the 82166C kit listed separately on page 23. Catalog #66 (1995) and #72 (1996) on the Museum CD-ROM has a Psion Series 3a with double of most specs of the Series 3, plus a Lotus 123-compatible spreadsheet.

There is a Psion website:


with the same logo, now they specialize in mobile connectivity and digital radio.


The Psion website has a link for an online store, you can see some of their recent/current products:



I don't have any HHP product - the brochure came to me in a box with a 71B. But after reflecting on the description in the brochure, I think it would not be very hard to make a custom ROM because of what appears to be an equivalence between the RAM and ROM implemented in the combo device. First, I would build the set of files I want to ultimately have in the ROM, in a 32K block of RAM. Then I would write a program using PEEK to copy all the bytes out of the 32K block of RAM and save them in a binary file. Then I would use that binary file (converting into S-records or whatever is required by my EPROM burner) to burn a 27256. It sounds like there is a socket inside the module so you can change the EPROM at will. My scheme probably falls apart because there is some kind of file system written in the block of memory that makes it not relocateable. In that case it would be necessary to figure out where the pointers are and change them before burning the EPROM. The hardest part of my scheme is getting the data out of the 71 - I hope you have an 82164 HPIL/RS-232 interface (I wish I did!) If you do, and a freestanding EPROM burner with serial port, you could run everything from the 71.


Thanks a bunch Ellis (again).

The thought I had was to make my own JPC image on an EPROM, the content is fun and good.

I would believe (NOT know) that the JPC is made for ROM which should make things a bit easier. The location 5.00 is taken care of by the firm:, hardware, so in it goes (socket at will).

Making an image of the JPC should be relatively accomplishable.

Now the next issue is to make the DUMP to the RS232 port and the connected burner. (Got the RS232, not the burner).

would anyone know where to get a cheap burner (and the ROM) could FRYs help? Maybe I could find one @ebay

Thanks again for you help, awesome place this is...



There have been a lot of them on Ebay, I have bought a few myself! When I was shopping, the greatest interest seemed to be in certain small systems that plugged into PC's - I think Jameco might have been one brand that was commanding high prices - I remember them as a mail order electronics company. I was mainly interested in programming PLDs and I bought a standard Data I/O mainframe model that I had used before - I want to say 29C but that is an HP calculator! - anyway, what I got came with a PROM/EPROM plugin and I hoped to find a LogicPak plugin later to do PLDs The unit was in very bad shape, at least the plugin, it wouldn't reliably read an empty EPROM.

The problem with professional equipment like that is that it needs to be calibrated and sometimes isn't supported by the manufacturer's website unless you first pay to bring it up to a certain revision level. (The voice of my experience with Data I/O and Advin Systems) All this is compounded by the fact that in-circuit-programmable logic devices (including Flash EEPROM) are putting the manufacturers out of business.

There is a very simple EPROM burner that plugs into an old ISA PC slot and has a ZIF socket on a ribbon cable that sits next to the computer, made by Needham's Electronics. They have moved on to bigger and better things but were still supporting the little unit last time I looked. I bought one of these new a long time ago for $130 and it still works fine. It is very general purpose in design and they have been able to add new devices (not all!) via software and sometimes simple socket adapters (they do some EPROM microprocessors this way).

I just looked up Needham's and they are still in business, I even downloaded software for my unit which is called PB-10. They don't sell it any more, or any unit that needs a bus connector, but they have a number of systems that plug into a parallel port. The bottom end system is called EMP-10 and they call it an upgrade to the PB-10 (the software I downloaded includes files with EMP in the name), it does a limited number of devices and sells new for $220. I can only vouch for the PB-10, it is easy to use and reliable and well supported, and the company has been in business for over 10 years.

I'm looking at the software I downloaded (the machine is in another room) and it can use binary files or Intel Hex or Motorola S-records or two other file types I don't recognize.

Here is Needham's web site:



On the EPROM (I assume it needs a 28 pin DIP - Dual Inline Plug - part) - the Fry's near me has a small selection of electronic parts in individual bags hanging from pegboards, including some EPROMs. Not the "NTE" replacement line, which Fry's also carries, but just Fry's own bagged parts. That might be as good a place as any to get one part. Or you could try DigiKey:


This page has Fairchild DIP EPROMs for $3.62:


Note that "OTP" means "one time programmable", an erased EPROM in a plastic package without a quartz window that can't be erased again. This page has Atmel DIPs for $1.94, but they are OTP:


Another place is Mouser Electronics:


This page has ST DIPs for $3.30:


This page has Fairchild DIPs for $6.44:


This page has Atmel OTP DIPs for $3.30:


Both catalogs have 32 pin PLCC OTP's. My HHP brochure doesn't specify, so I assume it uses 28 pin DIP EPROMs.

If it does have a PLCC socket - they do (or used to) make PLCC-type EPROMs in ceramic packages with quartz windows, but they never fit in the sockets very well - the "P" in PLCC means plastic and the real similar part in ceramic is the "leadless chip carrier", so the compromise ceramic PLCC is really a leadless chip carrier with "J" leads brazed on, it just doesn't take the socket's spring force as well as a real PLCC.

The Mouser website is better - you can browse lists of part numbers for categories like "EPROMs", then after selecting a part, you go to a PDF of the catalog page with prices and more specs.

You can find EPROMs in various old electronic equipment like VGA boards, motherboards, disk drives - if it has a paper label, peel it off and see if it has a quartz window and the right part number. Then you'd need to erase it - I've heard you can erase EPROMs by leaving them in the full sun for some time (days?) Whether with sunlight or a proper eraser, to erase it completely you have to remove every bit of adhesive left by the label, 91% rubbing alcohol is good for this.

BTW, DigiKey carries the Needham's programmers, this pdf is the page from their online catalog:


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